Start with the failure mode
Tool steel is used for cutting, forming and shaping other materials. Its selection starts with what ends the tool’s useful life: worn edges, chipping, heat softening, cracking or loss of dimensional accuracy. Choosing the highest hardness alone can trade a wear problem for brittle failure.
| Observed problem | First checks | Material emphasis |
|---|---|---|
| Abrasive wear | Working material, lubrication and actual treatment | Wear resistance at a usable toughness. |
| Chipping | Edge geometry, support, impact and alignment | Toughness alongside compressive strength. |
| Thermal softening | Operating temperature and heat flow | Hot hardness and tempering resistance. |
| Cracking / heat checking | Failure origin, thermal cycling and stress concentrations | Toughness, thermal fatigue and treatment quality. |
| Dimensional change | Machining, treatment and finishing sequence | Stability and appropriate stock allowance. |
Scroll within the table to see all columns →
This is a decision table for an investigation, not a diagnosis from a photograph.
Cold-work, hot-work and high-speed examples
D2 is a familiar cold-work designation associated with wear-resistant tooling. H13 is a hot-work example. M2 is a high-speed steel example associated with cutting-tool demands. These labels identify different application families; cold-work does not mean cold-rolled stock.
BÖHLER’s October 2018 tool-steel guide provides historical producer examples and designation context. Exact product data, heat treatment and available section are needed for an actual comparison.
Reading family letters without ranking grades
| Family | Selection context |
|---|---|
| W | Water-hardening carbon tool steels; check section and quench-distortion risk. |
| O / A / D | Oil-hardening, air-hardening and high-carbon/high-chromium cold-work groups; balance wear, toughness and stability. |
| S | Shock-resisting grades where impact and chipping matter. |
| H | Hot-work grades for elevated-temperature tooling and thermal cycling. |
| P | Mould steels: consider supplied hardness, machining and required surface finish. |
| M / T | Molybdenum- and tungsten-type high-speed steels; cutting performance includes hot hardness. |
Scroll within the table to see all columns →
The public scopes of ASTM A686-92(2024) , A681-24 and A600-92a(2024) separate carbon, alloy and high-speed tool-steel products. Use the contract edition and grade-specific producer data; a family letter does not prescribe a furnace cycle.
| Example | Wear question | Toughness question | Hot-hardness question |
|---|---|---|---|
| D2 — cold work | Does abrasive edge wear dominate? | Will corners or impact cause chipping at the selected hardness? | Do not select it solely for a hot-work duty. |
| H13 — hot work | What wear occurs at the actual working temperature? | How severe are thermal cycling and mechanical shock? | Check tempering resistance and hot-service data for the grade. |
| M2 — high speed | What cutting-edge wear mechanism is limiting? | Is the cutting edge sufficiently supported? | Retaining hardness in hot cutting is a key selection requirement. |
Scroll within the table to see all columns →
This map asks comparative questions rather than assigning invented scores. Use an actual manufacturer’s grade datasheet for temperatures, holding time, quenching and tempering; this page deliberately supplies no universal heat-treatment temperature.
Heat treatment and final dimensions
Many tool steels arrive annealed for machining; some products are supplied prehardened. Record the supplied state and the final state separately. The finished tool’s properties depend on the grade-specific hardening/tempering route, section and inspection.
Rough machining, thermal treatment, grinding and surface treatment belong in one manufacturing plan. Check dimensions after the stages that can change them. A surface coating needs a suitable substrate and support; it cannot compensate for a cracked or incorrectly treated tool.
Conventional and powder-metallurgy routes
Powder-metallurgy processing offers another way to produce tool-steel structures. voestalpine’s tooling overview describes conventional and PM offerings. Compare a named grade against the failure mode, working material and tool geometry. PM is a production route, not a universal ranking above every conventional grade.
If the existing tool is failing at an unsupported sharp corner, geometry and loading may deserve attention before changing alloy. If gradual abrasion is the limiting issue, grade-specific wear/toughness data is more directly relevant.
Keep a useful tool record
Record grade and producer variant, stock section, supply condition, heat-treatment record, final hardness/test method, critical dimensions and any coating. Add the operation, working material and documented failure location. This gives a replacement trial a defined comparison basis.
The bar reference covers incoming stock; alloy steel explains hardenability through a section; annealed steel explains machining preparation.