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Tool Steel

S7 Tool Steel

S7 is a shock-resistant tool steel built for high impact toughness rather than maximum wear or hardness. At a hardened ~56 HRC it intentionally trades some hardness for the ability to absorb heavy blows without chipping or cracking, with 2100 MPa tensile. It is the steel of choice where tools take repeated impact that would shatter harder, more brittle grades.

How S7 Tool Steel machines

Machinability is 2.4/5 in the annealed condition. Machine S7 annealed, then heat treat. It cuts moderately with carbide using rigid setups and steady feeds. After hardening to ~56 HRC, finish by grinding or EDM. Its lower target hardness leaves more impact toughness, which is the whole point of the grade.

Manufacturing & processing

Processed by CNC and forging. S7 is air hardening in smaller sections and oil quenched in larger ones, then tempered. Machine in the annealed state, harden, and finish-grind. Because it is run at lower hardness for toughness, it tolerates shock loads that would fracture wear-optimized steels.

Typical applications

Best for shock-resistant chisels and punches. Typical uses include cold chisels, punches, shear blades, riveting and forming dies, hammers, and impact tooling where the dominant failure mode is chipping or breakage under heavy, repeated blows rather than gradual wear.

When to choose it

Choose S7 when impact toughness is the priority and the tool sees heavy shock, such as punches and chisels. If abrasive wear dominates, D2 or A2 last longer. If the tool runs hot, H13 is correct. S7 wins where things hit hard.

Suitable surface finishes

Common finishes for S7 Tool Steel: black oxide, nickel plating. Use the finish selector →

FAQ

Why is S7 called shock-resistant?
S7 is formulated and run at a lower hardness, around 56 HRC, to maximize impact toughness. This lets it absorb repeated heavy blows in punches and chisels without chipping or fracturing, unlike harder, more brittle cold-work steels.
How does S7 compare to A2 for punches?
S7 offers higher impact toughness, so it resists breakage under shock far better than A2. A2 provides better wear resistance at higher hardness. Choose S7 when repeated impact is the threat and A2 when abrasive wear dominates the failure mode.
Should S7 be machined annealed?
Yes. Machine S7 in the annealed state, then harden and finish by grinding or EDM. Like all tool steels, it is cut soft and heat treated afterward, since the hardened ~56 HRC is impractical for conventional machining.

Property values are typical/nominal for early guidance and vary by temper, grade, supplier and heat treatment. Confirm critical specs against a certified datasheet or with an mfgiq engineer.