Best Grade of Tool Steel in 2026

D2 is a high-carbon, high-chromium cold work steel, and its large carbides give it outstanding wear resistance in cutting, blanking and slitting work. Typical hardness in supplier guides sits around 58 to 62 HRC, with some guides listing up to 64 HRC, and that hardness helps D2 hold an edge through long runs where a softer grade would wear quickly. It is a natural choice for long-run dies, shear blades and knives that face abrasive material.

The trade-off is toughness and machining. D2 is more brittle than A2, so it can chip under shock or in thin sections, and its carbide load makes machining and grinding slower. Choose D2 when wear is the clear failure mode and the tool will not face heavy impact. If chipping is your main problem, A2 or S7 will serve you better.

A2 is an air-hardening cold work steel that sits in the middle of the tool steel map, and that middle position is why many shops pick it first. It offers better toughness than D2 and better wear resistance than S7, with typical hardness around 58 to 62 HRC. Air hardening also gives excellent dimensional stability, so dies and punches distort less after heat treatment than oil-hardening grades.

That balance makes A2 a strong general choice for blanking and piercing dies, forming tools and medium-run punches where tolerances matter. It will not outlast D2 in a pure abrasive wear job, and it will not survive the hardest impacts like S7. For a shop that needs one grade to cover many jobs well, A2 is the safest starting point.

O1 is an oil-hardening cold work steel known for ease of machining and shaping, with typical hardness around 58 to 62 HRC in supplier guides. It is a practical choice for short-run dies, simple tools, gauges and knives where the tool will not face a long abrasive run. Shops like O1 for prototypes because it machines well and heat treatment is straightforward for smaller sections.

The limits show up in longer runs and larger tools. O1 wears faster than A2 or D2, and oil hardening can cause more distortion than air hardening in larger or complex sections. Use O1 when the job is short, the shape is simple and machining time matters more than maximum tool life.

S7 is a shock-resisting tool steel, and its job is to survive impact that would chip or break a harder, more brittle grade. Typical hardness sits around 54 to 58 HRC, lower by design, because that hardness range supports toughness under repeated shock. It is used for heavy-duty punches, shear blades, chisels and tools that face cyclic impact loading.

Wear life is the compromise. S7 will not match D2 for abrasive wear, and it is not the right pick for a long-run cutting job where wear is the main failure mode. Choose S7 when fracture or breakage is the primary risk, and accept shorter wear life in exchange for a tool that stays in one piece.

M2 is a molybdenum high-speed steel used for cutting tools that run hot, such as drill bits, taps, milling cutters and reamers. Its alloy content lets it retain hardness at high temperatures, with typical hardness around 62 to 66 HRC in supplier guides, so it keeps cutting when a cold work grade would soften. That hot hardness is the reason M2 remains a standard for high-speed cutting.

M2 is not a general die steel. Its toughness is moderate, and it machines and grinds more slowly than A2 or O1. For cold work dies, A2 or D2 will usually be a better fit. For rotating cutting tools that generate heat, M2 is a proven and widely stocked choice.

H13 is a hot work tool steel built for tools that face heat cycle after cycle, such as die casting molds, extrusion tooling and hot forging dies. It combines toughness with resistance to thermal fatigue, with typical hardness around 54 to 56 HRC in hot work use, and it holds strength at temperatures where cold work grades would fail. That heat tolerance is its defining strength.

At room temperature, H13 does not match D2 for wear resistance, and it is not the right grade for cold blanking or slitting. Choose H13 when the tool will be heated, cooled and heated again, and when cracking from thermal cycling is the failure you need to prevent. For plastic molds, P20 may be a simpler and cheaper alternative.

M42 is a cobalt high-speed steel, an upgrade over M2 for cutting jobs that run hotter or cut harder materials. The added cobalt improves red hardness, meaning the tool keeps its edge at higher temperatures, and wear resistance at temperature is stronger than M2. It is used for drills, taps, end mills and saws that cut stainless steel, high-strength alloys and other difficult materials.

Cost and toughness are the limits. M42 costs more than M2, and it is less forgiving under shock or interrupted cuts. Use it when heat or material hardness is clearly limiting M2 tool life, and keep feeds and setup stable so the edge is not asked to survive impact as well as heat.

P20 is a pre-hardened mold steel widely used for plastic injection molds, large tooling plates and holders. It is typically supplied pre-hardened to around 28 to 32 HRC, so shops can machine a large mold block without a separate hardening step and long lead time. That supply condition, plus good polishability for mold surfaces, makes P20 practical for large mold work.

P20 is not a cutting or die steel. Its hardness is far below D2, A2 or M2, so it will not hold a cutting edge or survive abrasive blanking. Choose P20 when the job is a mold or a large support tool where machinability, size availability and surface finish matter more than edge wear.