Tool and die steels are high carbon steels (either carbon or alloy) possessing high hardness, strength and wear resistance.
Tool steels are heat treatable.
In order to increase hardness and wear resistance of tool steels, alloying elements forming hard and stable carbides (chromium, tungsten, vanadium, manganese, molybdenum) are added to the composition.
Designation system of one-letter in combination with a number is accepted for tool steels.
The letter means:
§ W – Water hardened plain carbon tool steels
§ O, A, D – Cold work tool steels
§ S – Shock resistant low carbon tool steels
§ T,M – High speed tool steels (T-tungsten, M-molybdenum)
§ H – Hot work tool steels
§ P – Plastic mold tool steels
Chemical compositions of some tool and die steels
Properties of some tool and die steels
W – Water hardened plain carbon tool steels
Applications: chisels, forging dies, hummers, drills, cutters, shear blades, cutters, drills, razors.
Properties: low cost, very hard, brittle, relatively low hardenabilityhardenability, suitable for small parts working at not elevated temperatures.
O, A, D – Cold work tool steels
Applications: drawing and forging dies, shear blades, highly effective cutters.
Properties: strong, hard and tough crack resistant.
O -Oil hardening cold work alloy steels;
A -Air hardening cold work alloy steels;
D -Diffused hardening cold work alloy steels;
S – Shock resistant low carbon tool steels
Applications: tools experiencing hot or cold impact.
Properties: combine high toughness with good wear resistance.
T,M – High speed tool steels (T-tungsten, M-molybdenum)
Applications: cutting tools.
Properties: high wear heat and shock resistance.
Applications: parts working at elevated temperatures, like extrusion, casting and forging dies.
Properties: strong and hard at elevated temperatures.
Applications: molds for injection molding of plastics.
Properties: good machinability.
Chemical compositions of some tool and die steels
| AISI No. | C, % | Mn,% | W,% | Si,% | Cr,% | Mo,% | V,% | Co,% |
| W1 | 1.0 | 0.35 | 0.30 | – | – | – | – | – |
| O1 | 0.95 | 1.1 | 0.5 | 0.30 | 0.5 | – | – | – |
| A2 | 1.0 | 0.30 | – | 0.30 | 5.0 | 1.0 | – | – |
| D2 | 1.55 | 0.30 | – | 0.30 | 12.0 | 1.0 | – | – |
| S1 | 0.5 | 0.30 | 2.5 | 0.30 | 1.5 | – | – | – |
| T15 | 1.6 | 0.30 | 12.0 | 0.30 | 4.0 | – | 5.0 | 5.0 |
| M2 | 0.9 | 0.30 | 6.0 | 0.30 | 4.0 | 5.0 | 2.0 | – |
| H13 | 0.35 | 0.40 | – | 1.0 | 5.0 | 1.5 | 1.0 | – |
| P20 | 0.4 | 1.5 | – | 0.4 | 1.9 | 0.2 | – | – |
