Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module
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Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module

Release: 2026-07-10

This version:
https://w3id.org/pmd/hto/3.0.0
Revision:
3.0.0
Authors:
https://orcid.org/0000-0002-9014-2920
https://orcid.org/0009-0004-4787-4685
Divya Gosula
Contributors:
https://orcid.org/0000-0003-1649-6832
Download serialization:
JSON-LD RDF/XML N-Triples TTL
License:
https://creativecommons.org/licenses/by/4.0/
Visualization:
Visualize with WebVowl
Cite as:
PMD Heat Treatment Ontology. Version 3.0.0, https://w3id.org/pmd/hto/
Vocabulary maintained at:
https://github.com/materialdigital/heat-treatment-application-ontology
Provenance of this page
Ontology Specification Draft

Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module: Overview back to ToC

This ontology has the following classes and properties.

Classes

Annotation Properties

Named Individuals

Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module: Description back to ToC

This ontology module is part of the Platform Material Digital Application Ontology (PMDao) and covers concepts related to heat treatment processes, parameters, and materials. It is designed to facilitate data integration, sharing, and analysis in the field of materials science and engineering, particularly focusing on heat treatment applications.

Cross-reference for Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module classes, object properties and data properties back to ToC

This section provides details for each class and property defined by Platform Material Digital Application Ontology (PMDao) - Heat Treatment Module.

Classes

A1 transformation temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000085

Equilibrium temperature defining the lower limit of austenite (3.12) existence.
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1.
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

A3 transformation temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000086

Equilibrium temperature defining the upper limit of ferrite (3.85) existence.
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1.
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

Am transformation temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000087

Equilibrium temperature defining the upper limit of cementite (3.39) existence in a hypereutectoid steel (3.117).
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1. 4885 names this 'Am'; the 'Acm' altLabel is the IIW/ASM-standard naming retained for industry compatibility.
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000039

Heat treatment (3.108), consisting of heating (3.109) and soaking (3.185) at a suitable temperature followed by cooling (3.45), such that an equilibrium-near microstructure is reached at room temperature.
editorial note
DIN audit fix (2026-06-09): hto-edit.owl HTO_0000039 currently has only an @en label 'annealing' and no DE label. DIN EN ISO 4885 §3.8 lemma is 'Glühen'. The DE label is added via skos:prefLabel. NB: 4885 §3.8 Anm.1 organises Glühen as a parent of named children (Blankglühen, Normalglühen, Weichglühen, zwischenkritisches Glühen, isothermes Umwandeln, etc.); subclasses HTO_0000093..HTO_0000102 below populate this Glühen-family per DIN 683-7 §6.2.1 granularity contract.
Source
DIN EN ISO 4885:2018, §3.8
has super-classes
P M D 0000779 c
has sub-classes
bright annealing c, diffusion annealing c, full annealing c, inter-critical annealing c, isothermal transformation c, normalizing c, recrystallization annealing c, soft annealing c, solution annealing c, stress-relief annealing c

austemperingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000103

Isothermal heat treatment to produce a bainitic (cf. 3.17, 3.18) or ausferritic (cf. 3.9) microstructure in a workpiece.
editorial note
DIN audit addition (2026-06-09): isothermal-treatment process from DIN EN ISO 4885 §3.11. Closely related to Bainitisieren (HTO_0000104, §3.18).
Source
DIN EN ISO 4885:2018, §3.11
is equivalent to
bainitising c
has super-classes
P M D 0000779 c

austenitec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000077

Microstructure that is a solid solution of one or more elements in γ-iron (3.91).
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.12 + Tabelle 1. Parent BFO_0000040 (material entity) selected as the closest BFO anchor for a phase as a material-bearer; some HTO maintainers may prefer to re-anchor under a PMDco material-phase class once one is added upstream.
All term definitions copied from DIN 4885 should be rid of the internal reference number e.g. "3.91" (thnlrd)
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.12
has super-classes
P M D 0000857 c

austenitizing pointc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000011

needs more work; austenitic phase can be reached from at least two temperatures for any given material (from liquid or from ferrite)
A realizable entity of a material which marks the phase change to austenite (γ-iron).
Source
DIN 17022-1:1994, §3.1.1
DIN EN ISO 4885:2018, §3.14
DIN EN ISO 4885:2018, §3.213
DIN EN ISO 683-5:2021, Tab.7 col.3
has super-classes
P M D 0020167 c

bainitec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000079

Microstructure resulting from a transformation of austenite (3.12) at temperatures above the martensite (3.137) start temperature (Ms) and outside the range of pearlite (3.155), consisting of ferrite laths with carbides arranged either within (lower bainite) or between (upper bainite) the ferrite laths.
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.17 + Tabelle 1.
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.17
has super-classes
P M D 0000857 c

bainitisingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000104

Austenitising (3.14) and quenching (3.168) to a temperature above Ms followed by isothermal hold at that temperature so that austenite (3.12) transforms into bainite (3.17).
editorial note
DIN audit addition (2026-06-09): process from DIN EN ISO 4885 §3.18.
Source
DIN EN ISO 4885:2018, §3.18
has super-classes
P M D 0000779 c

bright annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000097

Annealing (3.8) in a medium under conditions that prevent oxidation (3.150) and preserve the original surface quality.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.29.
Source
DIN EN ISO 4885:2018, §3.29
has super-classes
annealing c

carbon levelc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000076

Relational quality describing the carbon content (mass-fraction in %) that an austenitised pure-iron sample assumes in equilibrium with the carburising agent at a specified temperature.
editorial note
DIN audit addition (2026-06-09): DIN EN ISO 4885 §3.33 Anm.1 explicitly contrasts 'Kohlenstoffpegel' (operationally defined) with 'Kohlenstoffpotenzial' (thermodynamic) — the two are NOT synonymous. HTO's existing Carbon Potential carries the thermodynamic reading; this new class carries the §3.33 operational definition.
Source
DIN EN ISO 4885:2018, §3.33
DIN EN ISO 4885:2018, §3.33 Anm.1 (operational vs. thermodynamic contrast)
has super-classes
B F O 0000145 c

carbon potentialc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000112

See standard DIN 1310
Carbon content of a specimen of pure iron in equilibrium with a carbourizing medium under specific conditions.
editorial note
DIN audit (2026-06-09): DIN EN ISO 4885 §3.33 names the operational quantity 'Kohlenstoffpegel' (carbon level), with §3.33 Anm.1 contrasting it explicitly with the 'thermodynamisches Kohlenstoffpotenzial'. 4885 treats the two as NOT synonymous. hto:CarbonPotential is retained as the thermodynamic-potential quality; the new sibling hto:HTO_0000076 (CarbonLevel) carries the §3.33 operational definition. See hto:HTO_0000076 below for the sibling class.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN EN ISO 4885:2018, §3.33 (Kohlenstoffpegel — contrast Anm.1)
DIN EN ISO 683-3:2022, §A.4 (carburising atmosphere control)
has super-classes
B F O 0000145 c

carbonitridingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000075

Thermochemical treatment (3.207) to enrich the surface layer with carbon and nitrogen; carbonitriding is a carburising process (3.36).
editorial note
DIN audit re-IRI (2026-06-09): the legacy class <https://w3id.org/pmd/co/HTO_0000064> was misnamespaced under pmd/co/ (should have been pmd/hto/), and the local ID HTO_0000064 collided with <https://w3id.org/pmd/hto/HTO_0000064> (flow rate). Re-IRIed to hto:HTO_0000075. NB: §3.144 Anm.2 disjointness with Nitrocarburieren (HTO_0000074).
Source
DIN EN ISO 4885:2018, §3.35
has super-classes
P M D 0000779 c

carburizingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000025

Thermochemical treatment (3.207) to enrich the surface of an austenitised workpiece with carbon, which is then present in solid solution in austenite (3.12).
editorial note
DIN audit fix (2026-06-09): hto-edit.owl's existing rdfs:comment/skos:definition treats Aufkohlen as a 'surface hardening process'; DIN EN ISO 4885 §3.36 defines it as 'thermochemische Behandlung zum Anreichern der Oberfläche eines austenitisierten Werkstückes mit Kohlenstoff'. Hardening only follows IF quenching is subsequently applied (cf. §3.37 Einsatzhärten = Aufkohlen + Härten). Original rdfs:label preserved; the §3.36 verbatim definition is added via skos:definition as the canonical anchor.
Source
DIN EN ISO 4885:2018, §3.36
has super-classes
P M D 0000779 c

carburizing recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000122

Potentiell ableitbar mit bestimmten Fluss-Schwellenwerten
Heattreatment recipe outlining the steps and parameters needed to perform a carburizing process.
editorial note
needs work
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-3:2025-11, §6
has super-classes
P M D 0060008 c

case hardeningc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000072

Surface hardening process comprised of carburising, hardening and tempering of case hardnening steels.
editorial note
DIN audit (2026-06-09, γ refinement): HTO_0000072 (recently added upstream as case-hardening PROCESS) is overlaid here with DE label 'Einsatzhärten' and verbatim 4885 §3.37 wording. Earlier draft had a twin class hto:HTO_0000106; removed in favour of this overlay to keep upstream IRIs intact (Q2c style). HTO_0000106 slot vacated for Divya to re-claim. The depth measure CHD is the separate HTO_0000089 — do not conflate process with depth.
Source
DIN EN ISO 4885:2018, §3.37 (Einsatzhärten = Aufkohlen + Härten)
has super-classes
surface hardening c

case hardening depthc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000089

Distance from the surface of a workpiece to a point defining the thickness of the hardened (3.167) case.
editorial note
DIN audit addition (2026-06-09): case hardening depth (CHD) from DIN EN ISO 4885 §3.72 (sourced from ISO 18203:2016 §3.1 modified). IMPORTANT: CHD is the depth MEASURE; do NOT confuse with hto:HTO_0000072 'case hardening' which is the PROCESS (Einsatzhärten).
Source
DIN EN ISO 4885:2018, §3.72
ISO 18203:2016, §3.1 (modifiziert)
has super-classes
P M D 0040001 c

cementitec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000082

Microstructure composed of iron carbide with composition Fe3C.
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.39 + Tabelle 1.
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.39
has super-classes
P M D 0000857 c

chamberc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000109

unklare Zuordnung innerhalb der SDCs. Eine Kammer existiert nur als Teil eines Gerätes (Device), könnte aber selbst noch einmal als independent continuant definiert werden, da sich in der Kammer Chargen, Gestelle, Thermoelemente etc. befinden.
Systemboundary of a distinct Heattreatment Process. Includes a fluid that has the role of medium role (e.g., Helium or Vacuum).
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-1:1994, §7 (generic multi-chamber furnace construction)
Term status
needs work
has super-classes
B F O 0000024 c
has sub-classes
heating chamber c, quenching chamber c

chamber pressurec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000116

Effective atmosphere pressure in chamber to keep process save must be 2-3 mbar above ambient pressure.
A pressure which inheres within the confines (atmosphere) of an oven chamber.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-1:1994, §7 (chamber/Ofen-Konstruktion)
DIN 17022-4:1998, §7.3
DIN 17022-4:1998, §7.3 (Ofendruck)
DIN EN ISO 4885:2018, §3.165 (Ofenatmosphäre, related quality)
is equivalent to
P M D 0000896 c and (R O 0000080 op some chamber c)
has super-classes
P M D 0000896 c

compressorc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000050

A machine that increases the pressure of a gas by reducing its volume.
has super-classes
machinery c
is disjoint with
propeller c, turbopump c

coolantc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000071

editorial note
needs work
has super-classes
P M D 0020113 c

coolant rolec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000070

A medium role of a fluid to serve as an intermediary for the transmission of thermal energy from an object to the fluid.
has super-classes
P M D 0020114 c

cooling ratec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000031

A temperature change rate that is of negative value.
Source
DIN 17022-1:1994, §5.2.2 (Abkühlgeschwindigkeit)
DIN EN ISO 4885:2018, §3.52 (kritische Abkühlgeschwindigkeit)
is equivalent to
temperature change rate c and (P M D 0000077 op some O B I 0001931 c and (O B I 0001937 dp some ))
has super-classes
temperature change rate c

cooling recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000017

A heat treatment recipe describing the steps and parameters for carrying out a cooling process.
Source
DIN 17022-1:1994, §5.2.2
DIN EN ISO 4885:2018, §3.45
has super-classes
P M D 0060008 c
has sub-classes
quenching recipe c

counterc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000063

A data item that describes the position of an entity within a sequential chain of action with an integer value.
Example 
Numbering of subprocesses in a heat treatment sequence.
has super-classes
I A O 0000027 c

device operation statec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000033

A Device Operation State is a state that inheres in a device and specifies whether a device function is currently active or inactive, typically represented in a control or output protocol as an on/off (or analogous binary) indicator.
has super-classes
P M D 0060006 c

device operation state valuec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000034

A categorical value specification defining the on/off state of some device.
has super-classes
O B I 0001930 c
has members
OFF ni, ON ni

dew pointc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000118

dew point of the atmosphere, measured during process or calculated from lambda / oxygen probe signal
Is defined by
https://w3id.org/pmd/hto/
Source
DIN EN ISO 683-3:2022, §A.4 Anm. (Taupunkt as carburising atmosphere control variable)
has super-classes
I A O 0000109 c

diffusion annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000096

Heat treatment (3.108) / annealing (3.8) of ferrous products or workpieces to reduce segregation (3.179) and promote homogeneity through diffusion (3.63).
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.64.
Source
DIN EN ISO 4885:2018, §3.64
has super-classes
annealing c

durationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000009

a temporal interval that describes the temporal extent of a process which is demarcated by the distance of two temporal instants
Source
DIN 17022-1:1994, Bild 1 (Verweildauer/Erwärm-/Anwärm-/Durchwärm-/Haltedauer)
DIN EN ISO 683-2:2018, Tab.11 (Anlassdauer / Aust.-dauer)
has super-classes
B F O 0000202 c

duration specificationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000008

Device specification as part of a plan specification which specifies the duration of a given process.
Source
DIN 17022-1:1994, Bild 1 (Verweildauer / Erwärm-/Anwärm-/Durchwärm-/Haltedauer)
DIN 17022-1:1994, §5.2.1
DIN EN ISO 683-2:2018, Tab.11 Fn d, f
has super-classes
setpoint c

electric generatorc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000054

A machine that converts mechanical energy to electrical energy.
has super-classes
machinery c

electric motorc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000057

An engine which transforms electric energy into mechanical energy.
has super-classes
engine c

end timec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000060

A temporal instant that specifies the date(time) a process ended.
Source
DIN 17022-1:1994, Bild 1 (process-step end instants, operational usage)
Example 
09.06.2022 18:18:47
has super-classes
B F O 0000203 c
is disjoint with
start time c

enginec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000045

Engine supply the mechanical energy to power machinery.
A machine designed to convert one or more forms of energy into mechanical energy.
has super-classes
turbo machinery c
has sub-classes
electric motor c, heat engine c, turbine c
is disjoint with
machinery c

equalizationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000042

Durchwärmen des Bauteils, sodass Temperaturhomogenität erreicht wird. Anschließend kann ein Halten auf der Zieltemperatur erfolgen.
essential heat treatment process step during which temperature homogenization is achieved in the component.
editorial note
In practice, the English terms 'equalization' and 'soaking' are synonymous. The standard DIN EN ISO 4885 is ambiguous about the distinction between 'Halten' (§3.185) and 'Durchwärmen' (3.80), and also translates 'soaking' as 'Halten'. The diagram for '§3.80 Durchwärmen' shows the two processes in sequence, whereas the annotation for 'Halten' states that the discrete location within an object must be specified. However, I deem this unnecessary, since 'Halten'/'holding' refers to the process that follows the soaking step and ensures a homogeneous temperature distribution regardless of the location. (thnlrd)
Source
DIN 17022-1:1994, Bild 1 (Durchwärmdauer)
DIN EN ISO 4885:2018, §3.80 (thnlrd)
has super-classes
heat treatment operation c

evacuationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000066

essential heat treatment process that creates a vacuum. Removing atmoshpere and decreasing pressure.
Source
DIN 17022-4:1998, §7.3 (Plasmanitrieren — Ofendruck < 10 mbar via evacuation, operational)
has super-classes
heat treatment operation c

evacuation functionc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000067

A heat treatment function to decrease a volume's pressure to vacuum, removing possibly present gases and fluids.
Source
DIN 17022-4:1998, §7.3
has super-classes
P M D 0000781 c

fanc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000053

A powered machine that creates airflow.
has super-classes
machinery c

ferritec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000080

Microstructure of iron or steel with a body-centred cubic lattice structure.
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.85 + Tabelle 1.
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.85
has super-classes
P M D 0000857 c

flow measuring functionc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000029

A measuring function performed to determine the flow of fluids.
Source
DIN 17022-4:1998, §7.3 (atmosphere flow measurement)
has super-classes
P M D 0000847 c

flow ratec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000064

a process attribute quantifying the volume of a continuous substance that traverses a designated spatial boundary per unit of duration.
has super-classes
P M D 0000008 c

flow rate specificationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000065

Setpoint defining the flow rate of some fluid.
Source
DIN 17022-4:1998, §7.3 (atmosphere flow control)
has super-classes
setpoint c

full annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000102

Annealing (3.8) to achieve a spheroidal microstructure (see 3.190), which involves complete austenitisation (3.14) to a temperature above A3 (for hypoeutectoid steels) or above A1 (for hypereutectoid steels), followed by slow cooling (3.45), to achieve a microstructure close to thermodynamic equilibrium.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.89 (Full annealing — listed inline in §3.8 Anm.1 as a named Glühen child). Definition is paraphrased per 4885 conventions; the §3.89 verbatim entry uses generic 'Wärmebehandlung'.
deviating from the standard here because 'full annealing' ist supposed to fully transform the microstructure into austenite (hence the name) whereas comparable annealing procedures do not fully transform the material even though they are within the same T-range (normalizing, intercritical annealing). Additional info and explanation provided by TWaldenmaier. (thnlrd)
Source
DIN EN ISO 4885:2018, §3.8 Anm.1
DIN EN ISO 4885:2018, §3.89
has super-classes
annealing c

gas nitridingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000026

A nitriding process where nitrogen is supplied to the surface in gaseous form.
Source
DIN 17022-4:1998, §7.3
DIN EN ISO 4885:2018, §3.143 (inline)
has super-classes
nitriding c
is disjoint with
plasma nitriding c, salt bath nitriding c

hardenabilityc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000091

Relational quality describing the ability of steels to transform into martensite (3.137) and/or bainite (3.17).
editorial note
DIN audit addition (2026-06-09): material quality from DIN EN ISO 4885 §3.103. The §3.103 Anm.1 notes that Härtbarkeit is frequently quantified via the Stirnabschreckversuch (HTO_0000092).
Source
DIN EN ISO 4885:2018, §3.103
has super-classes
B F O 0000145 c

hardened materialc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000106

is equivalent to
P M D 0000000 c and (O B I 0000312 op some P M D 0000103 c)
has super-classes
P M D 0000002 c

hardening heat treatmentc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000040

Heat treatment process to increase the strength and hardness of the material by cooling it so that its microstructure transforms to the hardening structure.
Source
DIN 17022-1:1994, §3.1
DIN EN ISO 4885:2018, §3.167
Example 
Randschichthärten

Einsatzhärten
Nitrierhärten
has super-classes
P M D 0000103 c, P M D 0000779 c
has sub-classes
single hardening c, surface hardening c, through hardening c

hardening heat treatment recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000013

add target temperature in axioms, combine it with austenitisation temperature
A heat treatment recipe describing the steps and conditions for carrying out a hardening heat treatment process.
Source
DIN 17022-1:1994, §3.1
DIN EN ISO 683-2:2018, Tab.11
DIN EN ISO 683-3:2022, Tab.8
has super-classes

hardening recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000002

A hardeing recipe describing the steps and conditions for carrying out a hardening process.
has super-classes
P M D 0060008 c

heat enginec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000056

A system that transfers thermal energy to do mechanical or electrical work.
has super-classes
engine c
has sub-classes
internal combustion engine c, turbojet engine c

heat treatment operationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000000

intermediate class/grouping term, not to be instatialized
Essential processes that make up heat treatments and can be used like building blocks.
Source
DIN EN ISO 4885:2018, §3 (generic upper-level HT-process taxonomy)
DIN EN ISO 4885:2018, §3.167 (Härtung)
DIN EN ISO 4885:2018, §3.207 (thermochemische Behandlung)
DIN EN ISO 4885:2018, §3.8 (Glühen)
has super-classes
C O B 0000035 c
has sub-classes
equalization c, evacuation c, holding c

heating chamberc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000110

Distinguishable chamber of a heat treatment furnace with a heater.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-1:1994, §7 (Ofen-Konstruktion)
DIN 17022-4:1998, §10
has super-classes
chamber c

heating ratec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000030

A temperature change rate that is of positive value.
Source
DIN 17022-1:1994, Bild 5
DIN 17022-1:1994, §3.1.1 (Aufheizgeschwindigkeit)
is equivalent to
temperature change rate c and (P M D 0000077 op some O B I 0001931 c and (O B I 0001937 dp some ))
has super-classes
temperature change rate c

heating recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000004

A heat treatment recipe describing the steps and parameters for carrying out a heating process.
Source
DIN 17022-1:1994, §3.1.1
has super-classes
P M D 0060008 c

holdingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000061

Die HoldingTime ist stets mit einer vorhergehende SoakingTime verbunden.
essential heat treatment process step without temperature change in the furnace after the designated temperature was homogeneously reached within the part.
Source
DIN EN ISO 4885:2018, §3.185
has super-classes
heat treatment operation c

holding functionc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000012

A heat treatment function that, enables a system or device to hold the thermal energy of a material, typically to facilitate diffusion and phase transformation processes within the material.
Source
DIN 17022-1:1994, Bild 1
DIN EN ISO 4885:2018, §3.185
Example 
function of a furnace to hold its temperature at a specified temperature
has super-classes
P M D 0000781 c

holding recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000014

A heat treatment recipe outlining the steps and parameters for carrying out a holding process.
Source
DIN 17022-1:1994, §5.2.1
DIN EN ISO 4885:2018, §3.185
has super-classes
P M D 0060008 c

hydrogene sensor signalc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000119

nominal pre-set value of control system for hydrogen probe
measured hydrogen value of hydrogen probe measured in milli volt
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-4:1998, §7.3 (H2 atmosphere monitoring, p_H2 in K_N formula)
has super-classes
I A O 0000109 c

inter-critical annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000099

Annealing (3.8) of a hypoeutectoid steel (3.118), consisting of heating (3.109) and soaking at temperatures between A1 and A3 to partially produce austenit, followed by suitable cooling (3.45) tailored to the required properties.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.122.
Source
DIN EN ISO 4885:2018, §3.122
has super-classes
annealing c

internal combustion enginec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000058

An engine that uses combustion to turn chemical energy into mechanical energy by the transferral of kinetic energy from pressure increase of hot gas expansion into the movement of engine parts.
Example 
driven parts can be:
pistons (piston engine)
turbine blades (gas turbine)
rotor (Wankel engine)
nozzle (jet engine).
has super-classes
heat engine c

isothermal transformationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000100

Heat treatment (3.108) with austenitising (3.14), interrupted cooling (3.45), and isothermal hold at a specified temperature until transformation is complete.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.127. NB: 4885 §3.8 Anm.1 lists 'isothermes Umwandeln' as one of the named Glühen children.
Source
DIN EN ISO 4885:2018, §3.127
DIN EN ISO 4885:2018, §3.8 Anm.1
has super-classes
annealing c

Jominy end-quench testc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000092

Assay that is a standardised test method for assessing hardenability (3.103).
editorial note
DIN audit addition (2026-06-09): test method from DIN EN ISO 4885 §3.128. Reinforcing standards: ISO 642 (test procedure).
Source
DIN EN ISO 4885:2018, §3.128
ISO 642 (Jominy end-quench test procedure)
has super-classes
O B I 0000070 c

lambda probe signalc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000120

measured lambda probe signal in exhaust gas
editorial note
DIN audit (2026-06-09): 'Lambdasonde' is not explicitly named in DIN 683-3 §A.4 (it uses the generic 'Sauerstoffsonde'); the lambda probe is a specific O2-probe variant used for burner stoichiometry in fuel-fired furnaces. Provenance is operational / inferred, not direct.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN EN ISO 683-3:2022, §A.4 Anm. (atmosphere-control umbrella; lambda probe is industry-vendor term for the O2 probe class)
has super-classes
I A O 0000109 c

machineryc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000044

the mechanical energy needed for machines to work is supplied by engines/motors
A powered machine which takes up mechanical energy.
has super-classes
turbo machinery c
has sub-classes
compressor c, electric generator c, fan c, propeller c, turbopump c
is disjoint with
engine c

martensitec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000078

Microstructure/phase (3.156) formed in carbon-bearing steels by cooling (3.45) of austenite (3.12), where the high cooling rate prevents sufficient carbon atoms from diffusing out of the crystal structure to form cementite (3.39) (Fe3C).
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.137 + Tabelle 1.
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.137
has super-classes
P M D 0000857 c

martensite finish temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000084

Temperature at which the transformation of austenite into martensite is approximately complete upon cooling.
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1.
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

martensite start temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000083

Temperature at which the transformation of austenite into martensite (3.137) begins upon cooling (3.45).
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1 (Bei Stählen können im Wesentlichen folgende Umwandlungstemperaturen unterschieden werden).
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

mass flow controllerc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000028

Device that has the function to control the flow of fluid media to a defined mass flow. It consists of a mass flow meter and a proportional valve.
Source
DIN 17022-4:1998, §7.3 (atmosphere supply equipment, inline)
has super-classes
P M D 0000602 c

Mx transformation temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000108

Temperature at which, upon cooling, x % volume fraction of austenite has transformed into martensite.
editorial note
DIN audit addition (2026-06-09): transition temperature from DIN EN ISO 4885 §3.213 Anm.1 (parametric x ∈ (0,100)).
Source
DIN EN ISO 4885:2018, §3.213 Anm.1
has super-classes
P M D 0020167 c

nitridingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000041

DIN parameter coupling (DIN EN ISO 683-5 Tab.7 ANMERKUNG verbatim): 'Die Anlasstemperatur sollte nicht weniger als 50 °C über der Nitriertemperatur liegen.' OWL 2 DL cannot directly express the cross-class arithmetic constraint Anlass-T(Vergüten preceding) >= Nitrier-T(this Nitrieren) + 50 degC; recommended downstream encoding is SHACL (constraint language) or SWRL (rule extension). This rdfs:comment is the pristine v2 deliverable for this constraint.
A surface hardening process in which nitrogen is supplied to a material's surface with the goal to increase the nitrogen content in the surface of a sample or part.
editorial note
DIN audit fix (2026-06-09): DIN EN ISO 4885 §3.143 lemma is 'Nitrieren'; DIN 17022-4, DIN 17022-5, and DIN EN ISO 683-5 all use 'Nitrieren' exclusively. The hto-edit.owl DE label 'Nitridieren' is a non-DIN morphological variant. The canonical 'Nitrieren' is hoisted to skos:prefLabel; the legacy 'Nitridieren' is demoted to skos:hiddenLabel.
Source
DIN EN ISO 4885:2018, §3.143
has super-classes
P M D 0000779 c
has sub-classes
gas nitriding c, plasma nitriding c, salt bath nitriding c

nitriding hardness depthc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000073

the defined boundary value usually is set 50 HV above core hardness
Distance from the surface of a nitrided or nitrocarburised workpiece to the point at which the hardness equals a defined boundary value.
editorial note
DIN audit re-IRI (2026-06-09): the legacy class <https://w3id.org/pmd/co/HTO_0000039> was misnamespaced under pmd/co/ (should have been pmd/hto/), and the local ID HTO_0000039 collided with <https://w3id.org/pmd/hto/HTO_0000039> (annealing). Re-IRIed to hto:HTO_0000073 (next free above HTO_0000072 case hardening). owl:equivalentClass preserves A-Box / external compatibility; the legacy IRI is marked owl:deprecated below.
Source
DIN 17022-4:1998, §9.2 (Bild 7; via DIN 50190-3)
DIN EN ISO 4885:2018, §3.73
ISO 18203:2016, §3.4 (acceptance-criterion source — outside DIN corpus) DIN EN ISO 18203:2022-07 (https://dx.doi.org/10.31030/3344011)
has super-classes
P M D 0040001 c

nitriding recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000018

A heat treatment recipe outlining the steps and parameters for carrying out a nitriding process.
Source
DIN 17022-4:1998, §7
has super-classes
P M D 0060008 c

nitrocarburizingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000074

Thermochemical treatment (3.207) to produce a hard surface layer containing nitrides and nitrocarbides, forming a compound layer and an underlying diffusion layer.
editorial note
DIN audit re-IRI (2026-06-09): the legacy class <https://w3id.org/pmd/co/HTO_0000063> was misnamespaced under pmd/co/ (should have been pmd/hto/), and the local ID HTO_0000063 collided with <https://w3id.org/pmd/hto/HTO_0000063> (counter). Re-IRIed to hto:HTO_0000074. NB: DIN EN ISO 4885 §3.144 Anm.2 records disjointness with Carbonitrieren (HTO_0000075) — the two are NOT synonyms in DIN despite industry colloquial conflation.
Source
DIN 17022-4:1998, §4.2
DIN EN ISO 4885:2018, §3.144
has super-classes
P M D 0000779 c

nitrogen potentialc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000113

The nitriding potential is a key indicator how intensive the nitriding process is, the higher the value the stronger the nitriding conditions, unit is bar^-3/2
A relational quality describing the intensity of a nitriding atmosphere by relating the partial pressures of ammonia and hydrogen gas.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-4:1998, §7.3 eq.3 (K_N = p_{NH3} / p_{H2}^{1.5})
has super-classes
B F O 0000145 c

normalizingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000094

Heat treatment (3.108) aimed at refining and homogenising the grain size (3.99) of a ferrous product, consisting of heating (3.109) to a temperature slightly above A3 (A1 for hypereutectoid steels (3.117)), without prolonged soaking, followed by suitable cooling (3.45) to achieve a fine ferrite-pearlite microstructure.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.146. Aligns with DIN EN ISO 683-7 +N delivery state.
Source
DIN EN ISO 4885:2018, §3.146
DIN EN ISO 683-7:2025, §6.2.1 (+N delivery state)
has super-classes
annealing c

OBSOLETE surface hardening depth (generic)c back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000090

unnecessary grouping term
OBSOLETE Generic depth term for surface hardening; in industrial practice referred to as Surface Hardening Depth (SHD); in DIN normation usually narrowed to Rht (§3.74) or CHD (§3.72).
Is deprecated
true

oxygen probe signalc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000121

A measurement datum generated by an electrochemical or optical sensor, representing the specific concentration of elemental oxygen within a sampled medium.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN EN ISO 683-3:2022, §A.4 Anm. (Sauerstoffsonde / O2 probe for Cp atmosphere control)
has super-classes
I A O 0000109 c

partial pressurec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000114

Realtional quality describing the contribution from a single gas species to the total pressure in a gas mixture.
editorial note
DIN audit (2026-06-09): DIN EN ISO 4885 has no §3 entry for partial pressure; this is upstream physical-chemistry vocabulary, not DIN-terminology-native. Operational usage in DIN 17022-4 §7.3 (p_NH3, p_H2 in K_N formula) is the only DIN anchor.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-4:1998, §7.3 eq.3 (p_NH3, p_H2 in K_N formula)
has super-classes
B F O 0000145 c

patentingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000105

Heat treatment (3.108) consisting of austenitising (3.14) followed by suitable cooling (3.45) to produce a microstructure favourable for subsequent drawing or roll-drawing of wire or strip.
editorial note
DIN audit addition (2026-06-09): process from DIN EN ISO 4885 §3.154.
Source
DIN EN ISO 4885:2018, §3.154
has super-classes
P M D 0000779 c

pearlitec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000081

Microstructure constituent consisting of ferrite (3.85) and cementite (3.39) lamellae, formed by the eutectoidic transformation of austenite (3.56) and the concomitant transformation into ferrite and cementite.
editorial note
DIN audit addition (2026-06-09): Fe-C phase from DIN EN ISO 4885 §3.155 + Tabelle 1.
Source
DIN EN ISO 4885:2018, Tabelle 1 (Fe-C-Phasen)
DIN EN ISO 4885:2018, §3.155
has super-classes
P M D 0000857 c

plasma nitridingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000024

Nitriding (3.143) at a pressure that is usually below atmospheric pressure, using a plasma carrier to ionise the nitrogen.
Source
DIN 17022-4:1998, §7.3
has super-classes
nitriding c
is disjoint with
gas nitriding c, salt bath nitriding c

propellerc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000051

A powered machine with a rotating hub and radiating blades which exert linear thrust upon a working fluid such as water or air.
has super-classes
machinery c
is disjoint with
compressor c, turbopump c

QT recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000021

A heat treatment recipe outlining the steps and parameters for carrying out a quenching and tempering process.
Source
DIN 17022-1:1994, §3.3
DIN EN ISO 4885:2018, §3.169
DIN EN ISO 683-2:2018, Tab.11
is equivalent to
P M D 0060008 c and ((B F O 0000051 op some hardening heat treatment recipe c) and (B F O 0000051 op some tempering recipe c))
has super-classes
P M D 0060008 c

quenchantc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000068

editorial note
needs work
Source
DIN 17022-1:1994, Tab.2
DIN EN ISO 4885:2018, §3.170
DIN EN ISO 683-2:2018, Tab.11 Fn e
has super-classes
P M D 0020113 c

quenchant rolec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000069

A medium role of a fluid to serve as an intermediary for the transmission of thermal energy from an object to the fluid in a capacity that exeeds the transmission from static air.
has super-classes
P M D 0020114 c

quenchingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000062

essential heat treatment process in which a workpiece is cooled (3.45) at a higher rate than in still air.
Source
DIN EN ISO 4885:2018, §3.168
has super-classes
P M D 0025011 c

quenching and temperingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000022

Hardening (3.167) of a workpiece, followed by tempering, in order to produce a condition characterised by a good combination of hardness and toughness.
Source
DIN 17022-1:1994, §3.3
DIN EN ISO 4885:2018, §3.169
DIN EN ISO 683-2:2018, Tab.1 Zeile 5 (+QT)
has super-classes

quenching chamberc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000111

Chamber of a heat treatment furnace that is designed to quench objects.
Is defined by
https://w3id.org/pmd/hto/
Source
DIN 17022-1:1994, §7.2 (Abschreckeinrichtung)
DIN 17022-4:1998, §10.3 (Fassungsverhältnis ≥ 6× Chargengewicht)
has super-classes
chamber c

quenching functionc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000001

A quenching function is a (realizable) function that, when realized, enables a system to lower the temparature of a material fast enough, that it hinders diffusion processes and thus produces metastable material states.
Source
DIN 17022-1:1994, §3.1.2
DIN EN ISO 4885:2018, §3.168
Example 
The function of a oil bath to quench steel after austenitisation so the material transforms into martensite.
has super-classes
P M D 0000055 c

quenching recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000016

A heat treatment recipe describing the steps and conditions for carrying out a quenching process.
Source
DIN 17022-1:1994, §5.2.2
DIN EN ISO 4885:2018, §3.168
has super-classes
cooling recipe c

recrystallization annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000098

Annealing (3.8) to eliminate the strength increase from cold deformation and to renew grains via nucleation without phase change (3.156).
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.174.
Source
DIN EN ISO 4885:2018, §3.174
has super-classes
annealing c

rotation speed specificationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000117

seam to be a device specification pinting to a process charateristic of type speed
A setpoint describing the intended rotational speed of a device e.g. an fan or turbine.
editorial note
needs work
Is defined by
https://w3id.org/pmd/hto/
has super-classes
setpoint c

salt bath nitridingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000037

A nitriding process in which nitrogen is supplied to the surface by molten salt.
Source
DIN 17022-4:1998, §8
DIN EN ISO 4885:2018, §3.143 (inline)
has super-classes
nitriding c
is disjoint with
plasma nitriding c, gas nitriding c

setpointc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000032

Internally (within the devices' logic) a process is run to reach and maintain the given setpoint.
A Set Point is a specification datum that assigns a desired quantitative value to a controlled process parameter, serving as the normative reference for process execution and control.
editorial note
DIN audit (2026-06-09): DIN EN ISO 4885 does not enumerate 'Sollwert' as a §3 lemma; PMDco owns the generic 'setpoint' concept upstream. The DIN procedural anchor is DIN 17022-1 §5 (Sollwert / Solltemperatur operational usage). Provenance is therefore procedural rather than terminological.
Source
DIN 17022-1:1994, §5 (Sollwert / Solltemperatur, procedural usage)
Example 
The flow rate for a mass flow controller.
The target temperature in the furnace chamber for a given process step.
The rotational speed of a fan.
has super-classes
P M D 0060009 c
has sub-classes
duration specification c, flow rate specification c, rotation speed specification c, target pressure c, target temperature c, temperature change rate specification c

single hardeningc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000107

Single-step hardening following prior carburising (3.36) and slow cooling (3.45) to room temperature.
editorial note
DIN audit addition (2026-06-09): hardening sub-process from DIN EN ISO 4885 §3.184 (siehe Bild 1 b).
Source
DIN EN ISO 4885:2018, §3.184
has super-classes
hardening heat treatment c

soaking recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000015

A heat treatment recipe outlining the steps and parameters for carrying out a soaking process.
Source
DIN 17022-1:1994, Bild 1 (Durchwärmdauer)
DIN EN ISO 4885:2018, §3.185
has super-classes
P M D 0060008 c

soft annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000093

Heat treatment (3.108) to reduce the hardness of a ferrous product to a specified level.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.186. Aligns with DIN EN ISO 683-2 +A delivery state (weichgeglüht).
Source
DIN EN ISO 4885:2018, §3.186
DIN EN ISO 683-2:2018, §7.2 (+A delivery state)
has super-classes
annealing c

solution annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000101

Heat treatment (3.108) consisting of austenitising (3.14) at a high temperature followed by sufficiently rapid cooling (3.45) to prevent new precipitation upon return to ambient temperature.
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.188.
Source
DIN EN ISO 4885:2018, §3.188
has super-classes
annealing c

start timec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000059

A temporal instant that specifies the date(time) a process started.
Source
DIN 17022-1:1994, Bild 1 (process-step start instants, operational usage)
Example 
09.06.2022 17:48:47
has super-classes
B F O 0000203 c
is disjoint with
end time c

steam turbinec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000048

A machine that extracts thermal energy from pressurized steam and uses it to do mechanical work utilising a rotating output shaft.
has super-classes
turbine c

stress-relief annealingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000095

Annealing (3.8) at temperatures below A1 to reduce internal stresses without substantially altering the microstructure of a workpiece or ferrous product, followed by slow cooling (3.45).
editorial note
DIN audit addition (2026-06-09): Glühen-family subclass from DIN EN ISO 4885 §3.197. Aligns with DIN EN ISO 683-7 +SR delivery state.
Source
DIN EN ISO 4885:2018, §3.197
DIN EN ISO 683-7:2025, §6.2.1 (+SR delivery state)
has super-classes
annealing c

surface hardeningc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000019

Hardening (3.167) restricted to the surface layer.
editorial note
DIN audit fix (2026-06-09): DIN EN ISO 4885 §3.200 lemma is 'Randschichthärten'; DIN 17022-5 uses 'Randschichthärten' exclusively in its title. The hto-edit.owl DE label 'Oberflächenhärtung' is a DIN-10052 / legacy synonym (already retained in hto-edit.owl as skos:altLabel — preserved here). The DIN-canonical 'Randschichthärten' is hoisted to skos:prefLabel.
Source
DIN 17022-5:2000, §1
DIN 17022-5:2000, §4
DIN EN ISO 4885:2018, §3.200
has super-classes
hardening heat treatment c
has sub-classes
case hardening c
is disjoint with
through hardening c

surface hardening depthc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000088

Distance from the surface to the point at which the Vickers hardness (HV) equals 80% of the minimum required surface hardness for the workpiece.
editorial note
DIN audit addition (2026-06-09): surface hardening depth (Rht) from DIN EN ISO 4885 §3.74 (sourced from ISO 18203:2016 §3.5 modified). Distinct from CHD (HTO_0000089) which is the depth measure for Einsatzhärten.
Source
DIN EN ISO 4885:2018, §3.74
ISO 18203:2016, §3.5 (modifiziert)
has super-classes
P M D 0040001 c

target pressurec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000027

A setpoint describing the pressure that is to be reached/held within a process that involves a defined pressure.
editorial note
needs work
Source
DIN 17022-4:1998, §7.3 (Ofendruck < 10 mbar, Plasmanitrieren)
has super-classes
setpoint c

target temperaturec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000006

A setpoint defining the temperature that is to be reached/held within a process that involves a defined temperature.
editorial note
needs work
Source
DIN 17022-1:1994, §5 (generic process-target temperature)
has super-classes
setpoint c

temperature change ratec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000005

A process attribute defining the change of temperature per time unit within a process.
Source
DIN 17022-1:1994, §3.1.1
DIN 17022-1:1994, §5.2.2 (incl. kritische Abkühlgeschwindigkeit K_k)
has super-classes
P M D 0000008 c
has sub-classes
cooling rate c, heating rate c

temperature change rate specificationc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000003

A setpoint which - as part of plan specifications (e.g. recipes) - specifies the rate at which temparature is to be changed.
Source
DIN 17022-1:1994, §3.1.1
DIN 17022-1:1994, §5.2.2
has super-classes
setpoint c

temperature unitc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000010

working variable, used for testing only
Source
DIN EN ISO 4885:2018 (generic, °C usage throughout)
has super-classes
I A O 0000003 c

temperingc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000038

Heat treatment (3.108) of a steel product, generally carried out following hardening (3.167) or another heat treatment to achieve the required levels of properties, consisting of heating (3.109) to specific temperatures (< A1) and holding at these temperatures once or several times, followed by appropriate cooling (3.45)
Source
DIN 17022-1:1994, §3.2
DIN EN ISO 4885:2018, §3.203
has super-classes

tempering recipec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000023

add target temperature in axioms
A heat treatment recipe outlining the steps and parameters for carrying out a tempering process.
Source
DIN 17022-1:1994, §5.4
DIN 17022-5:2000, §6.5
DIN EN ISO 4885:2018, §3.203
DIN EN ISO 683-2:2018, Tab.11
DIN EN ISO 683-3:2022, Tab.8
has super-classes
P M D 0060008 c

through hardeningc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000020

Härtung (3.167), bei der die Bildung von Martensit (3.137) bis zum Kern eines Werkstückes erreicht wird.
Source
DIN EN ISO 4885:2018, §3.209
has super-classes
hardening heat treatment c
is disjoint with
surface hardening c

turbinec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000055

has super-classes
engine c
has sub-classes
steam turbine c, water turbine c, wind turbine c

turbo machineryc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000043

A device that extracts energy from or imparts energy to a continuously moving stream of fluid.
has super-classes
P M D 0000602 c
has sub-classes
engine c, machinery c

turbojet enginec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000049

combination of a gas turbine and and a propelling nozzle
has super-classes
heat engine c

turbopumpc back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000052

A machine powered by a gas engine to create high throughput and high pressure flow of fluid media.
has super-classes
machinery c
is disjoint with
compressor c, propeller c

water turbinec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000047

An engine which converts kinetic energy of water into rotational energy of a shaft connected to a generator.
has super-classes
turbine c

wind turbinec back to ToC or Class ToC

IRI: https://w3id.org/pmd/hto/HTO_0000046

An engine to convert kinetic energy of a gas (movement of air in the atmosphere, wind) into the rotation of a shaft which drives a generator.
has super-classes
turbine c

Annotation Properties

alt Labelap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#altLabel

bibliographic Citationap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/bibliographicCitation

commentap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#comment

contributorap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/contributor

createdap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/created

creatorap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/creator

definitionap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#definition

descriptionap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/description

editorial Noteap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#editorialNote

exampleap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#example

has Related Synonymap back to ToC or Annotation Property ToC

IRI: http://www.geneontology.org/formats/oboInOwl#hasRelatedSynonym

hidden Labelap back to ToC or Annotation Property ToC

IRI: http://www.w3.org/2004/02/skos/core#hiddenLabel

I A O 0000114ap back to ToC or Annotation Property ToC

IRI: http://purl.obolibrary.org/obo/IAO_0000114

I A O 0000116ap back to ToC or Annotation Property ToC

IRI: http://purl.obolibrary.org/obo/IAO_0000116

I A O 0100001ap back to ToC or Annotation Property ToC

IRI: http://purl.obolibrary.org/obo/IAO_0100001

licenseap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/license

P M D 0000060ap back to ToC or Annotation Property ToC

IRI: https://w3id.org/pmd/co/PMD_0000060

P M D 0000064ap back to ToC or Annotation Property ToC

IRI: https://w3id.org/pmd/co/PMD_0000064

repositoryap back to ToC or Annotation Property ToC

IRI: http://usefulinc.com/ns/doap#repository

sourceap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/source

titleap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/terms/title

typeap back to ToC or Annotation Property ToC

IRI: http://purl.org/dc/elements/1.1/type

Named Individuals

OFFni back to ToC or Named Individual ToC

IRI: https://w3id.org/pmd/hto/HTO_0000036

belongs to
device operation state value c
has facts
P M D 0000006 dp "false"^^boolean

ONni back to ToC or Named Individual ToC

IRI: https://w3id.org/pmd/hto/HTO_0000035

belongs to
device operation state value c
has facts
P M D 0000006 dp "true"^^boolean

Legend back to ToC

c: Classes
ni: Named Individuals

Acknowledgments back to ToC

The authors would like to thank Silvio Peroni for developing LODE, a Live OWL Documentation Environment, which is used for representing the Cross Referencing Section of this document and Daniel Garijo for developing Widoco, the program used to create the template used in this documentation.