Tabela de dureza Rockwell do aço para ferramentas 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.
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.
S7 Tool Steel Hardness Chart
Core tableThe table below summarizes typical S7 tool steel hardness values in annealed, as-quenched, tempered, and application-based conditions.
| S7 Condition | Dureza típica | Significado prático |
|---|---|---|
| Annealed condition | 187-223 HB | Normal supply condition for machining. |
| Annealed upper reference | about 230 HB max | Common upper limit in some supplier data. |
| As-quenched condition | 59-61 HRC | Maximum hardness before tempering. |
| General working condition | 54-58 HRC | Common range after hardening and tempering. |
| Balanced shock-resisting range | 56-58 HRC | Practical range for many punches, dies, and impact tools. |
| Heavy-impact tools | 50-54 HRC | Better toughness where cracking risk is high. |
| Higher edge-strength applications | 58-60 HRC | Higher hardness, but lower shock safety margin. |
| High-temperature tempered condition | about 45-46 HRC near 1100-1150 F | Used when high tempering temperature is required. |
Annealed S7 Hardness
Supply conditionS7 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
Tratamento térmicoAfter 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.
The final hardness depends on austenitizing temperature, quenching method, tempering temperature, section size, and service requirement. A hardness value on paper should always be matched to the tool’s actual working conditions.
How to Choose S7 Working Hardness
Service logicFor 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.
When cracking, chipping, or impact breakage is the main service risk, move toward a tougher and slightly softer range.
For many general punches, dies, and cold-forming tools, 56-58 HRC is the practical balance point.
When edge strength or deformation control matters more, higher hardness can help, but the shock margin becomes smaller.
S7 Hardness by Application
Application tableS7 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.
| Aplicativo | Typical S7 Hardness Range | Lógica de Seleção |
|---|---|---|
| General punches | 56-58 HRC | Balanced edge strength and shock resistance. |
| Matrizes de corte | 56-58 HRC | Suitable for impact-loaded cold-work tooling. |
| Lâminas de tesoura | 54-56 HRC | Lower hardness helps reduce chipping risk. |
| Cold-forming tools | 56-58 HRC | Combines strength, toughness, and moderate wear resistance. |
| Heavy-impact tools | 50-54 HRC | Better safety against cracking. |
| Chisels and battering tools | 54-58 HRC | Maintains impact absorption. |
| Cold swaging dies | 56-60 HRC | Higher compressive strength may be needed. |
| Cutting tools under shock load | 55-60 HRC | Used when both edge strength and toughness are required. |
| Medium or large molds | 53-56 HRC | Lower hardness may improve toughness and dimensional safety. |
| Moderate hot-work applications | about 45-57 HRC | Final hardness depends on tempering temperature and service heat. |
S7 HRC to HB Conversion
Approximate referenceAnnealed S7 is usually specified in Brinell hardness. Hardened and tempered S7 is usually specified in Rockwell C hardness.
The table below gives approximate HRC-to-HB references for hardened steel.
| Dureza Rockwell C | Approximate Brinell Hardness |
|---|---|
| 60 HRC | about 654 HB |
| 58 HRC | about 615 HB |
| 56 HRC | about 577 HB |
| 54 HRC | about 543 HB |
| 52 HRC | about 500-512 HB |
| 50 HRC | about 475-481 HB |
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.
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