Aobo Steel S7 Hardness Reference

Tabla de dureza Rockwell del acero para herramientas S7

S7 tool steel is usually supplied in the annealed condition at about 187-223 HB. After hardening and tempering, the common working hardness is about 54-58 HRC. For many shock-loaded tools such as punches, chisels, shear blades, and cold-forming tools, 56-58 HRC is often the practical center because it keeps useful edge strength while preserving S7’s main advantage: impact resistance.

Selection Position

S7 Hardness Should Be Chosen by Failure Mode, Not by Maximum HRC Alone

S7 can reach high hardness after quenching, but the best final condition depends on how the tool fails in service. Lower hardness usually gives better impact safety. Higher hardness may improve edge strength, but it also reduces the safety margin against chipping or cracking.

Shock Comes First S7 is valued mainly for impact resistance, so the working hardness should protect toughness as well as strength.

Tempering Matters As-quenched hardness is not the normal service condition. Tempering reduces stress and sets the final balance.

Verify by Test Paper values are useful for planning, but final hardness should still be confirmed by actual hardness testing.

S7 Tool Steel Hardness Chart

Core table

The table below summarizes typical S7 tool steel hardness values in annealed, as-quenched, tempered, and application-based conditions.

Condición S7	Dureza típica	Significado práctico
Condición recocida	187-223 HB	Normal supply condition for machining.
Referencia superior recocida	aproximadamente 230 HB máximo	Common upper limit in some supplier data.
Estado de temple	59-61 HRC	Maximum hardness before tempering.
Condiciones generales de funcionamiento	54-58 HRC	Common range after hardening and tempering.
Gama equilibrada resistente a los golpes	56-58 HRC	Practical range for many punches, dies, and impact tools.
Herramientas de alto impacto	50-54 HRC	Better toughness where cracking risk is high.
Aplicaciones de mayor resistencia en los bordes	58-60 horas de duración	Higher hardness, but lower shock safety margin.
Condición templada a alta temperatura	about 45-46 HRC near 1100-1150 F	Used when high tempering temperature is required.

These values are useful for material selection, purchase discussion, and heat-treatment planning. Final hardness should still be confirmed by actual hardness testing after heat treatment.

Annealed S7 Hardness

Condición de suministro

S7 tool steel is normally supplied in the annealed condition because the material must be machinable before final hardening.

In this condition, Brinell hardness is more useful than Rockwell C hardness. The common annealed range is 187-223 HB, while some supplier references use 200-225 HBW or an upper reference of about 230 HB.

Annealed S7 should not be judged as too soft simply because it is below its final working hardness. This is the correct condition for cutting, milling, drilling, grinding, and preparing the tool before heat treatment.

S7 Hardness After Hardening and Tempering

Tratamiento térmico

After hardening, S7 can reach about 59-61 HRC in the as-quenched condition. This is a heat-treatment stage, not the normal service condition.

The steel must be tempered to reduce internal stress and adjust the final balance between hardness and toughness. For most practical tooling applications, S7 is used around 54-58 HRC.

La dureza final depende de la temperatura de austenización, el método de temple, la temperatura de revenido, el tamaño de la sección y los requisitos de servicio. El valor de dureza indicado en el papel siempre debe corresponderse con las condiciones reales de trabajo de la herramienta.

How to Choose S7 Working Hardness

Service logic

For S7 tool steel, the highest HRC value is not always the best target.

A tool hardened close to 60 HRC may have higher edge strength, but it can lose part of the impact resistance that makes S7 useful. For repeated shock loading, a slightly lower hardness often gives better service life.

If the tool chips, cracks, or breaks under impact, a lower hardness range is usually safer. If the tool deforms or wears too quickly, higher hardness may help, but a more wear-resistant grade may also be a better choice.

Choose Lower

When cracking, chipping, or impact breakage is the main service risk, move toward a tougher and slightly softer range.

Choose Center

For many general punches, dies, and cold-forming tools, 56-58 HRC is the practical balance point.

Choose Higher Carefully

When edge strength or deformation control matters more, higher hardness can help, but the shock margin becomes smaller.

Dureza S7 por aplicación

Application table

S7 hardness should be selected according to the tool’s failure risk. Tools exposed to heavy impact often require greater toughness. Tools exposed to wear, cutting, or deformation may need higher hardness.

Aplicación	Rango típico de dureza S7	Lógica de selección
golpes generales	56-58 HRC	Balanced edge strength and shock resistance.
Matrices de corte	56-58 HRC	Suitable for impact-loaded cold-work tooling.
Cuchillas de corte	54-56 HRC	Lower hardness helps reduce chipping risk.
Herramientas de conformado en frío	56-58 HRC	Combines strength, toughness, and moderate wear resistance.
Herramientas de alto impacto	50-54 HRC	Better safety against cracking.
Cinceles y herramientas de golpeo	54-58 HRC	Maintains impact absorption.
Troqueles de forjado en frío	56-60 HRC	Higher compressive strength may be needed.
Herramientas de corte sometidas a carga de choque	55-60 HRC	Used when both edge strength and toughness are required.
Moldes medianos o grandes	53-56 HRC	Lower hardness may improve toughness and dimensional safety.
Aplicaciones de trabajo en caliente de intensidad moderada	about 45-57 HRC	Final hardness depends on tempering temperature and service heat.

For most S7 tooling, 56-58 HRC is the practical center. Lower hardness improves shock safety. Higher hardness improves edge strength, but it also reduces the safety margin against cracking.

S7 HRC to HB Conversion

Approximate reference

El acero S7 recocido se suele especificar en dureza Brinell. El acero S7 templado y revenido se suele especificar en dureza Rockwell C.

The table below gives approximate HRC-to-HB references for hardened steel.

Dureza Rockwell C	Dureza Brinell aproximada
60 HRC	aproximadamente 654 HB
58 HRC	aproximadamente 615 HB
56 HRC	aproximadamente 577 HB
54 HRC	aproximadamente 543 HB
52 HRC	about 500-512 HB
50 HRC	about 475-481 HB

These values are approximate conversions only. They should not replace actual hardness testing when a purchase order, drawing, or inspection report requires a specific hardness scale.

For annealed S7, with hardness around 187-223 HB, Rockwell C conversion is less reliable and less useful. In this soft condition, HB or HBW should be used as the main hardness reference.

Need S7 Tool Steel in Annealed Supply Condition?

Share your required size, quantity, delivery condition, and destination. Aobo Steel can support bulk S7 tool steel supply for distributors, stockists, and industrial tool-making projects.

Abrir formulario de contacto View S7 Tool Steel Page