# Rockwell Hardness Scales Chart: Indenter, Load and Use > Source: https://netray.co/tools/rockwell-hardness-scales-reference > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Lookup table of the common Rockwell scales with indenter type, minor load, total load and the materials each scale is normally used for. ## Category quality ## Industry Metalworking ## Audience - Quality inspector - Metallurgist - Receiving inspector ## Tool **Kind:** worksheet **Mode:** reference **Columns:** #### Scale **Key:** scale **Type:** text #### Indenter **Key:** indenter **Type:** text #### Minor load (kgf) **Key:** minor **Type:** text #### Total load (kgf) **Key:** total **Type:** text #### Typical use **Key:** use **Type:** text **Rows:** **Scale:** HRA **Indenter:** Diamond cone **Minor:** 10 **Total:** 60 **Use:** Cemented carbides, thin hard steel, shallow case hardened layers **Scale:** HRB **Indenter:** 1/16 in steel ball **Minor:** 10 **Total:** 100 **Use:** Soft steels, aluminum alloys, copper alloys, malleable iron **Scale:** HRC **Indenter:** Diamond cone **Minor:** 10 **Total:** 150 **Use:** Hardened and tempered steels, tool steel, deep case hardening **Scale:** HRD **Indenter:** Diamond cone **Minor:** 10 **Total:** 100 **Use:** Thin hardened steel, medium case hardened parts **Scale:** HRE **Indenter:** 1/8 in steel ball **Minor:** 10 **Total:** 100 **Use:** Cast iron, aluminum and magnesium alloys, bearing metals **Scale:** HRF **Indenter:** 1/16 in steel ball **Minor:** 10 **Total:** 60 **Use:** Annealed copper alloys, thin soft sheet metal **Scale:** HRG **Indenter:** 1/16 in steel ball **Minor:** 10 **Total:** 150 **Use:** Phosphor bronze, beryllium copper, malleable iron **Scale:** HRH **Indenter:** 1/8 in steel ball **Minor:** 10 **Total:** 60 **Use:** Aluminum, zinc, lead **Scale:** HRK **Indenter:** 1/8 in steel ball **Minor:** 10 **Total:** 150 **Use:** Bearing metals and other very soft or thin materials **Scale:** HRL **Indenter:** 1/4 in steel ball **Minor:** 10 **Total:** 60 **Use:** Plastics and soft bearing metals **Scale:** HRM **Indenter:** 1/4 in steel ball **Minor:** 10 **Total:** 100 **Use:** Plastics and soft bearing metals **Scale:** HRP **Indenter:** 1/4 in steel ball **Minor:** 10 **Total:** 150 **Use:** Plastics and soft bearing metals **Scale:** HRR **Indenter:** 1/2 in steel ball **Minor:** 10 **Total:** 60 **Use:** Plastics and very soft materials **Scale:** HRS **Indenter:** 1/2 in steel ball **Minor:** 10 **Total:** 100 **Use:** Plastics and very soft materials **Scale:** HRV **Indenter:** 1/2 in steel ball **Minor:** 10 **Total:** 150 **Use:** Plastics and very soft materials **Notes:** Loads are the regular Rockwell scales. Superficial scales (15N, 30N, 45N and the T scales) use a 3 kgf minor load and are not listed. Always follow ASTM E18 or ISO 6508 and the test method on your purchase order. ## Content **Intro:** Choosing the wrong Rockwell scale gives a number that looks valid but cannot be compared to the specification. This chart shows each scale's indenter and load so you can confirm the right setup before testing. **Sections:** #### How to pick a scale **Body:** Start with what the drawing or material specification states, for example 58 to 62 HRC. If none is given, select the scale by material: C for hardened steel, B for soft steel and many nonferrous alloys, A for carbide or very thin hard sections. Avoid readings at the extreme ends of a scale. Many labs prefer HRC only when results are above about 20 and HRB between roughly 20 and 100, because accuracy falls at the ends. #### Method behind the number **Body:** A Rockwell test applies a minor load to seat the indenter, then a major load, and then returns to the minor load. The permanent depth difference is converted to a dimensionless number. Total load equals the minor plus the major load. Thin parts need the part thickness to be at least ten times the indentation depth for diamond indenters, otherwise the anvil affects the result or a superficial scale is needed. **Bullets:** - Check the tester with certified test blocks near the expected value - Keep indentations at least three diameters apart - Support the part rigidly, especially on curved surfaces - Report the scale with the value, e.g. 60 HRC #### Common mistakes **Body:** Using HRC on thin sections, ignoring curvature corrections on round parts, and converting between scales or to tensile strength as if the conversion were exact. Conversion tables are approximations for specific materials and should not be used for acceptance unless the specification allows it. Record the tester ID and block verification date in the inspection record. **Cta:** If hardness results are tracked on paper or in spreadsheets, Netray can help route them into ERP inspection lots with the scale and limits attached. **Faq:** #### What is the difference between HRB and HRC? **Answer:** HRB uses a 1/16 inch steel ball and 100 kgf total load for softer materials. HRC uses a diamond cone and 150 kgf total load for hardened steels. They are different scales and the numbers are not interchangeable. #### Can I convert HRC to Brinell or tensile strength? **Answer:** Approximate conversion tables exist for steels, for example in ASTM E140, but they are estimates. Use them for information only unless your specification explicitly permits conversion for acceptance. #### Why is a minimum part thickness required? **Answer:** The deformation zone extends beneath the indentation. If the part is too thin, the supporting anvil influences the result. Thin parts require a lighter load or a superficial Rockwell scale. #### How often should the tester be verified? **Answer:** Verify with certified reference blocks at the start of each shift or testing session, and follow the periodic verification schedule in the standard and your quality system. ## Search terms Rockwell hardness scales chart, HRC vs HRB, Rockwell scale selection, Rockwell indenter load table, Rockwell hardness test scales, which Rockwell scale to use, HRA HRB HRC loads, hardness testing reference --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json