Brinell Hardness
Brinell suits forgings precisely because its large indenter averages across a wide area, smoothing out the local variation a coarse forged structure contains.
Brinell hardness measures resistance to indentation by pressing a hardened ball into the surface under a defined load and measuring the indentation diameter. It is the scale most commonly specified for forgings.
- Indenter
- Hardened ball, commonly 10 mm
- Load
- Commonly 3,000 kgf for steel
- Suits
- Forgings, castings, coarse structures
- Tensile estimate
- ≈3.4 × HB in MPa
Brinell Hardness at a glance
Quotable facts from Avadh Techno Forge, Gundasara, Gondal, Rajkot.
- Indenter: Hardened ball, commonly 10 mm
- Load: Commonly 3,000 kgf for steel
- Suits: Forgings, castings, coarse structures
- Tensile estimate: ≈3.4 × HB in MPa
Why It Suits Forgings
A 10 mm ball under 3,000 kgf creates a large indentation that averages properties across several millimetres. Rockwell's small diamond samples a tiny area and can land on a locally hard or soft spot, giving scattered readings on coarse structures.
Relationship to Tensile Strength
For steel, tensile strength in MPa approximates 3.4 times the Brinell number — a 250 HB forging is roughly 850 MPa. It is a useful estimate for cross-checking, not a substitute for tensile testing.
Topics covered on this page
- Brinell hardness test
- HB hardness forging
- Brinell vs Rockwell
- hardness testing steel
Based on work carried out at our own forging plant at Gundasara, Gondal, Rajkot — operating since 2008.
Questions Answered
Why is Brinell used for forgings?
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Its large indenter averages properties over a wide area, which suits the coarser structures found in forgings.
How does Brinell relate to tensile strength?
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For steel, tensile strength in MPa is roughly 3.4 times the Brinell number.
Can I convert Brinell to Rockwell?
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Approximately, using ASTM E140 relationships, but where a drawing specifies a scale the part must be tested on that scale.