Reviewed · 2026-08-21
Tool Steel
Tool steels are ordered as tooling systems: the steel grade, metallurgical quality, stock condition, tool geometry, heat treatment, surface finishing and operating temperature jointly determine whether wear, chipping, gross fracture, heat checking or surface failure controls life.
Classification basis
Operating temperature, dominant failure mode, tool geometry, heat-treatment response and required surface quality
A failure-mode-led guide to cold-work, hot-work, high-speed, shock-resisting and mold steels, with separate ordering evidence for each system.
A familiar grade name never replaces the governing product specification and certified documentation.01
Explore subcategories
Cold-Work Tool Steel
Use this group for cold forming and cutting loads; it does not predict hot-die thermal-fatigue life, high-speed cutting-edge behavior or mold polish quality.
→Tool steelHot-Work Tool Steel
Cold-work wear rankings cannot predict die-casting, extrusion or forging life because heat checking and premature thermal cracking are distinct failure modes.
→Tool steelHigh-Speed Steel
High-speed steel is not a generic high-hardness substitute for shock tools, large hot-work dies or cold-work parts where red hardness is irrelevant.
→Tool steelShock-Resisting Tool Steel
This family addresses impact-led failure at moderate temperature; it should not be selected by D-series abrasive-wear rankings or high-speed red-hardness comparisons.
→Tool steelMold Steel
Mold steel is a tooling procurement category rather than one chemistry family; it excludes dies chosen mainly for hot-metal contact or cutting-edge wear.
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Representative grades and systems
| Grade / system | Use as a selection entry point |
|---|---|
| D2 | Classify the observed or credible failure as abrasive wear, adhesive wear, plastic deformation, chipping, gross fracture, thermal fatigue or surface-quality loss. |
| A2 | Use operating temperature and contact cycle to choose the correct tool-steel family before comparing grades. |
| O1 | Match tool section, geometry and furnace/quench capability to through-hardening and distortion risk. |
| H13 | Set steelmaking quality, surface allowance and inspection around the life-limiting defect or finish requirement. |
| M2 | Classify the observed or credible failure as abrasive wear, adhesive wear, plastic deformation, chipping, gross fracture, thermal fatigue or surface-quality loss. |
| M42 | Use operating temperature and contact cycle to choose the correct tool-steel family before comparing grades. |
| S7 | Match tool section, geometry and furnace/quench capability to through-hardening and distortion risk. |
| P20 | Set steelmaking quality, surface allowance and inspection around the life-limiting defect or finish requirement. |
| 1.2738 | Classify the observed or credible failure as abrasive wear, adhesive wear, plastic deformation, chipping, gross fracture, thermal fatigue or surface-quality loss. |
| 420 mold quality | Use operating temperature and contact cycle to choose the correct tool-steel family before comparing grades. |
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Property framework
Working hardness and carbide-supported wear resistance must be balanced against chipping and fracture.
Tempering response and section hardenability control whether the target structure is achieved through the tool.
Thermal fatigue, red hardness and hot strength matter only for the tool systems exposed to sustained or cyclic heat.
Polishability, texture response, cleanliness and hardness homogeneity can matter more than peak hardness in mold service.
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Common product forms
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Applications
- Blanking, forming, coining and cold-shear tooling
- Forging, extrusion, die-casting and hot-stamping dies
- Drills, taps, broaches and high-speed cutting tools
- Plastic molds, impact tools and repairable production tooling
- Classify the observed or credible failure as abrasive wear, adhesive wear, plastic deformation, chipping, gross fracture, thermal fatigue or surface-quality loss.
- Use operating temperature and contact cycle to choose the correct tool-steel family before comparing grades.
- Match tool section, geometry and furnace/quench capability to through-hardening and distortion risk.
- Set steelmaking quality, surface allowance and inspection around the life-limiting defect or finish requirement.
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Standards and designation systems
ASTM A681-24 for applicable wrought alloy tool-steel products
ASTM A600-92a(2024) for applicable high-speed tool-steel products
ASTM A686-92(2024) for applicable wrought carbon tool-steel products
Tool drawing and qualified heat-treatment procedure control the finished tool condition
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Procurement checklist
- State standard, grade, product form, dimensions, stock condition and manufacturing route.
- Define annealed hardness, machining allowance, decarburization, macrostructure and cleanliness requirements.
- Assign heat-treatment responsibility and specify final hardness, tempering verification and test location.
- Add UT, microstructure, distortion, grinding-burn, polish or texture acceptance according to the tool's failure mode.
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Sources and editorial review
ASTM International · A681-24, A600-92a(2024), A686-92(2024)
SAE International · J402_202403
Uddeholms AB · Technical guide, May 2024
Uddeholms AB · Current technical record, accessed 2026
Erasteel · Technical data, 2024
Uddeholms AB · Current technical record, accessed 2026