Tool Steel Selection Reference
How to Select Tool Steels
A practical route from application to grade. Relative property ratings for ten common tool steels, a selection table by application and working condition, and the technical checks to run before a grade is fixed. Use it as a starting point, then confirm with your heat treater and a service trial.
Abrasion resistance resistance to abrasive wear Toughness resistance to cracking and impact failure Machinability ease of machining in tool making Grindability ease of grinding, finishing and sharpening
1. Property ratings of common tool steels Relative ratings for ten grades that cover most die, tool and mold work. Higher is better for every column, and all four columns share the same scale.
| Grade | Type | Abrasion resistance | Toughness | Machinability | Grindability |
|---|---|---|---|---|---|
| High-speed tool steels | |||||
| M4 | High-speed, molybdenum | 103 | 14 | 60 | 10 |
| M2 | High-speed, molybdenum | 95 | 20 | 65 | 10 |
| Cold-work tool steels | |||||
| D2 | Cold work, high-chromium | 100 | 20 | 60 | 10 |
| A2 | Cold work, air-hardening | 65 | 40 | 65 | 44 |
| O1 | Cold work, oil-hardening | 50 | 14 | 90 | 72 |
| A8 | Cold work, air-hardening | 48 | 75 | 60 | 75 |
| O6 | Cold work, oil-hardening | 44 | 10 | 125 | 76 |
| Hot-work tool steels | |||||
| H13 | Hot work, chromium | 30 | 100 | 75 | 100 |
| Shock-resisting tool steels | |||||
| S5 | Shock-resisting | 44 | 90 | 65 | 85 |
| S7 | Shock-resisting | 42 | 103 | 75 | 92 |
- (a) Abrasion resistance. M4, D2, and M2 have the highest abrasion-resistance ratings in this comparison.
- (b) Toughness. S7, H13, and S5 have the highest toughness ratings in this comparison.
- (c) Machinability. O6 and O1 are easier to machine than high-wear-resistance grades such as D2, M2, and M4.
- (d) Grindability. H13, S7, and S5 are easier to grind, while D2, M2, and M4 are more difficult.
- (e) Reading the bars. All four properties are indexed on the same relative scale, so a longer bar means a higher rating for that property, not a higher overall ranking of the grade.
2. Tool steel selection by application Starting point by tool and working condition. It does not replace application testing or heat-treatment confirmation. Grade names link to the grade pages.
| Application / tool | Working condition | Main required property | General grade | Higher-performance grade |
|---|---|---|---|---|
| Cutting tools | Light cuts, slow speeds | Wear resistance with acceptable grindability | O1, A2 | M2 |
| Cutting tools | Heavy cuts, fast speeds | Wear resistance and hot hardness | M2 | M4, T1, M42 |
| Boring tools | Metal cutting | Hot hardness and wear resistance | M2 | M4 |
| Broaches | Metalworking | Wear resistance and hot hardness | M2 | M4 |
| Form cutters | Profile cutting | Wear resistance and hot hardness | M2 | M4 |
| Milling cutters | Continuous cutting | Hot hardness and edge wear resistance | M2 | M4 |
| Thread cutters | Thread cutting | Wear resistance and hot hardness | M2 | M4 |
| Woodworking cutters | Edge wear with regrinding requirement | Wear resistance and grindability | O1 | M2 |
| Cold shear blades | Light gauge stock | Wear resistance with moderate toughness | A2 | D2 |
| Cold shear blades | Heavy gauge stock | Impact resistance and cracking resistance | S5 | S7 |
| Hot shear blades | Hot cutting | Hot hardness and toughness | S7, A8 | H13, H21 |
| Paper knives | Edge wear | Wear resistance | D2 | M2, M4 |
| Rotary knives | Continuous cutting wear | Wear resistance | A8 | D2 |
| Chipper knives | Impact and edge wear | Toughness with wear resistance | A2, A8 | D2, M2 |
| Blanking dies | Cold work, short runs | Balanced wear resistance and machinability | O1, O6 | A2 |
| Blanking dies | Cold work, long runs | Wear resistance and dimensional stability | A2 | D2, M2 |
| Bending dies | Cold forming | Toughness and dimensional stability | O1, O6 | A2, D2 |
| Coining dies | High pressure cold work | Wear resistance and compressive strength | O1 | A2, D2 |
| Embossing dies | Cold pressure and surface detail | Wear resistance and dimensional stability | A2 | D2 |
| Cold forming dies | General forming | Wear resistance with stability | O1 | A2, D2 |
| Hot forming dies | Hot work | Hot hardness and toughness | H13, S7 | H21 |
| Cold extrusion dies | High pressure and wear | Wear resistance with enough toughness | D2 | M2 |
| Hot extrusion dies for aluminum | Heat softening and thermal fatigue | Hot hardness and toughness | H13 | H11, H21 |
| Hot extrusion dies for copper and brass | Higher hot wear and thermal load | Hot hardness and thermal resistance | H13 | H21 |
| Die casting dies | Thermal fatigue, heat checking, cracking | Hot work stability | H13 | Premium H13 / ESR H13 |
| Brass die casting dies | Higher hot wear | Hot hardness and heat resistance | H13 | H21 |
| Hot forging dies | Heat, impact, thermal fatigue | Toughness and hot hardness | H13, S7 | H21, H43 |
| Hot trimming dies | Hot impact and edge damage | Toughness and hot hardness | S7, H13 | H21 |
| Cold heading tools | Impact, pressure, wear | Toughness and wear resistance | A2, S7 | D2, M2 |
| Cold punches | Piercing, trimming, forming | Wear resistance and toughness | A2, S7 | D2, M2 |
| Heavy-duty punches | Shock-loaded punching | Toughness first | S5 | S7 |
| Draw punches | Drawing pressure and wear | Wear resistance and toughness | A2, D2 | M2 |
| Thread rolls | Surface pressure and wear | Wear resistance | D2 | M2 |
| Forming rolls | Rolling pressure and wear | Wear resistance and dimensional stability | O1, A2 | D2, D7 |
| Drive rolls | Wear under contact pressure | Wear resistance | D2 | D7 |
| Wire drawing tools | Sliding wear and surface pressure | Wear resistance | D2 | M4 |
| Plug gauges | Wear and dimensional stability | Wear resistance and stability | A2 | D2 |
| Master hobs | Accuracy and wear resistance | Wear resistance and stability | S7 | A2, D2 |
| Cutting hobs | Cutting wear and heat | Hot hardness and wear resistance | M2 | T1 |
| Lathe tools | Cutting heat and wear | Hot hardness | M2 | M42 |
| Planer tools | Cutting wear | Hot hardness and wear resistance | M2 | M4 |
| Shaper tools | Cutting wear | Hot hardness and wear resistance | M2 | M4 |
| Reamers | Cutting accuracy and wear | Wear resistance and hot hardness | M2 | M4 |
| Taps | Thread cutting wear | Wear resistance and hot hardness | O1 | M2 |
| Drills | Cutting heat and edge wear | Hot hardness and wear resistance | M2 | M4 |
| Drill bushings | Wear from repeated drilling | Wear resistance | S5 | A2 |
| Brake dies | Bending pressure | Toughness and wear resistance | 4140 HT | A2 |
| Gripper dies, cold | Holding pressure and wear | Wear resistance and toughness | O1, S7 | A2, D2 |
| Gripper dies, hot | Hot gripping and wear | Hot hardness and toughness | S7, H13 | H21 |
| Swaging dies, cold | Impact and forming pressure | Toughness and wear resistance | S7 | D2 |
| Swaging dies, hot | Heat and impact | Hot hardness and toughness | H13, S7 | H21 |
| Lamination dies | Wear and edge stability | Wear resistance | A2 | D2, M2 |
| Plastic molds | Machining, polishing, mold surface quality | Machinability and polishability | P20, H13 | 420, special mold steels |
| Impact tools | Repeated shock | Toughness | S5 | S7 |
| Battering tools, cold | Shock and breakage | Toughness | S5 | S7 |
| Blacksmith tools | Impact and heat | Toughness | S5 | S7 |
| Boiler-shop tools | Impact work | Toughness | S5 | S7 |
| Chisels, cold working | Impact and edge chipping | Toughness | S5 | S7 |
| Chisels, hot working | Heat and impact | Toughness and hot hardness | S7 | M2 |
| Pneumatic tools | Repeated impact | Toughness | S5 | S7 |
| Concrete breakers | Severe impact | Toughness | S5 | S7 |
| Screwdriver bits | Torsion and impact | Toughness | S5 | S7 |
| Arbors | Support and wear | Toughness and dimensional stability | O1, O6 | A2, D2 |
| Collets | Holding pressure and wear | Toughness and wear resistance | O1 | S5, S7 |
| Chuck jaws | Holding pressure and impact | Toughness | S5 | S7 |
3. Selection notes How to read the failure mode before changing a grade.
| Selection note | Meaning |
|---|---|
| If the tool wears gradually, start by comparing wear-resistant grades. | D2, M2, M4, and related grades are common starting points for abrasive wear. |
| If the tool chips, cracks, or breaks suddenly, check toughness before increasing hardness. | S7, S5, H13, and other tougher grades may be more suitable for shock-loaded tools. |
| If the tool works under heat, room-temperature hardness is not enough. | Hot hardness and resistance to softening become more important. |
| If the tool requires frequent sharpening, grindability affects maintenance cost. | High-wear-resistance grades may be harder to grind. |
| If the tool is large or complex, heat-treatment distortion must be considered. | Air-hardening grades are often used where dimensional stability is important. |
| If the production run is short, the highest-performance grade may not be economical. | Machinability and material cost may be more important for short-run tooling. |
| If the production run is long, higher wear resistance may reduce total cost. | More expensive grades can be justified when they reduce downtime and replacement frequency. |
4. Final technical check before grade selection Confirm these nine points with the tool shop and heat treater before the grade is fixed.
| Check item | Confirm before selection |
|---|---|
| Tool function | Cutting, shearing, forming, drawing, extrusion, rolling, impact, molding |
| Working temperature | Room temperature, warm work, hot work |
| Main failure mode | Wear, chipping, cracking, softening, deformation, distortion |
| Load level | Light, medium, heavy, shock-loaded |
| Production volume | Short run, medium run, long run |
| Section size | Small tool, thick section, large die block |
| Heat treatment target | Required hardness, toughness, distortion control |
| Finishing requirement | Machining, grinding, polishing, sharpening |
| Cost target | Material cost, machining cost, maintenance cost, cost per part |
Faster route by application
The tool steel material finder starts from the application and narrows to suitable grades.
Property data behind the ratings
Wear, toughness, hot hardness and working hardness for 75 AISI grades are listed in general properties of tool steels.
Tool steel supply support
Aobo Steel supplies common tool steel grades for bulk orders, including D2, A2, S7, H13, H11, O1 and M2. Send the grade, size, quantity and destination port, or use the contact page.
Email [email protected] · Tel and WhatsApp +86 180 6294 5370
Related reference pages
General properties of tool steels · Tool steel composition chart · Grade comparison and equivalents · Hot hardness chart · Hardening and tempering temperatures · Machinability ratings
Grade families: cold-work tool steels · hot-work tool steels · high-speed steels · plastic mold steels · tool steel material finder · tool steel catalog
Property ratings are relative comparison values for selection, not mechanical test results. Application notes are a starting reference only: final performance depends on steel quality, heat treatment, section size, tool design and service conditions. Verify the grade and the heat-treatment procedure before production.