Rockwell B
Common for softer metallic conditions where the selected scale and thickness meet ASTM E18 requirements.
Technical guide
Stainless Steel Hardness Chart
A hardness value is incomplete without the test scale, method, load, surface preparation, thickness, location and material condition.
Common scalesRockwell, Brinell, Vickers
Condition mattersAnnealed, cold worked, hardened
Conversion ruleApproximate and material-dependent
Decision summary
Select the test scale from condition and geometry
Annealed sheet, hardened martensitic parts, weld zones and field components may require different methods even when the grade name is the same.
Rockwell C
Common for hardened martensitic and precipitation-hardening conditions; verify thickness and support.
Brinell
Uses a larger indentation and can represent bulk material, but location may still not represent the entire product.
Vickers
Useful across a wide hardness range and for smaller zones when load, preparation and spacing are controlled.
Microindentation
Useful for thin layers, weld zones or gradients; requires careful preparation and method reporting.
Portable testing
Useful when size or location prevents laboratory testing, but the governing method and its limitations must be agreed.
Reference table
Hardness scale selection chart
This chart selects a method; it does not assign a universal hardness number to a grade.
| Material or test situation | Scale to review | Why it may fit | Report at minimum |
|---|---|---|---|
| Annealed austenitic sheet or bar | HRB, HBW or HV | Lower hardness range and general product verification | Method, scale, load, location, condition |
| Cold-worked austenitic product | HRB/HRC or HV as applicable | Hardness varies with amount and location of cold work | Reduction/condition, orientation, location |
| Hardened martensitic stainless | HRC or HV | Higher hardness after quench and temper | Heat treatment, scale/load, surface prep |
| Precipitation-hardening stainless | HRC, HBW or HV | Aging condition controls properties | Exact H condition, test method, location |
| Duplex solution-annealed product | HBW, HRC/HRB or HV per specification | Product standard defines acceptance scale/limit | Grade, product standard, condition, method |
| Weld, HAZ or thin cross-section | HV or microindentation method | Small indent can map local gradients | Load, spacing, traverse, preparation, diagram |
| Large installed component | Portable method if approved | Component cannot enter a fixed machine | Device, calibration, surface, correlation and uncertainty |
Use the scale and acceptance limit named by the governing product specification. Hardness conversions are approximate and should not replace a required direct test.
Need hardness as an acceptance requirement?
State the grade, product standard, condition, scale, test method, locations, sampling and acceptance limit.
Working method
Write a reproducible hardness requirement
The number becomes auditable only when the method and specimen conditions are controlled.
Name the test standard
Specify ASTM E18, E10, E92/E384, E110 or the method required by the product specification.
Define material condition
Record grade, heat treatment, cold work, weld condition and product geometry.
Control the test location
Specify surface, distance from edge or weld, number of readings and sampling plan.
Report the complete result
Include value, scale, load where applicable, equipment verification, preparation and any conversion.
Limits and escalation
Avoid misleading hardness comparisons
Do not omit the scale
A bare value such as “90 hardness” is unusable without HRB, HRC, HBW, HV or another designation.
Conversions are approximate
ASTM E140 conversions depend on material class and valid range; converted values are not direct measurements.
Geometry affects readings
Thin sections, curvature, rough surfaces and poor support can invalidate or bias results.
Hardness is local
One indentation may not represent a cold-work gradient, weld zone, decarburized surface or entire part.
Visual process context
Make the test method and material condition visible together.
Use one image for the hardness measurement setup and another for the product condition or acceptance record.
Interactive planning aid
Choose a hardness method starting point
Select the material condition or test situation. Confirm the final method with the product standard and testing laboratory.
Frequently asked questions
Stainless steel hardness FAQ
The scale depends on grade, condition, thickness, geometry and product specification. HRB is common for softer conditions and HRC for harder heat-treated conditions, while HBW and HV are also widely used.
Only approximately and only within valid material and range limits. Use ASTM E140 where permitted, and do not replace a required direct measurement with a conversion.
No. Hardness changes with annealing, cold work, product form and location. Order and inspect against the condition and product specification.
Surface preparation, thickness, support, curvature, location, microstructure, cold-work gradient and machine verification can all affect results.
Method, sources and review
Traceable sources and review status
Official Rockwell and superficial Rockwell hardness test methods.
Official Brinell hardness test method for metallic materials.
Official ASTM listing for active indentation and portable hardness methods.
Official overview connecting stainless product specifications with hardness and mechanical testing.
Apply the current contract-specified method and product standard. Values, conversions and method selections on this page are planning guidance, not acceptance certificates.
Hardness testing context
Treat the hardness value, scale and test location as one requirement.
A hardness chart guides screening, but the relevant scale, condition, test method, sampling position and acceptance range must be stated for a meaningful result.
- Test scale
- Material condition
- Acceptance range