Inspection method · HT
Hardness testing
Hardness is the quickest indicator of material condition and heat treatment. Method choice and surface preparation matter.
01How it works
Hardness tests measure resistance to indentation. Brinell (HBW) uses a carbide ball and large load, suited to castings and forgings. Rockwell (HRC, HRB) measures indentation depth and is fast for hardened parts. Vickers (HV) uses a diamond pyramid and covers a wide range, including microhardness and weld traverses.
Portable methods include rebound (Leeb, HL) and ultrasonic contact impedance (UCI). They are useful on site but sensitive to mass, thickness and surface finish, and their conversions are approximate.
02Typical industrial applications
- Heat treatment verification
- Weld and HAZ hardness for sour service
- Case hardened parts
- Castings and forgings acceptance
- Wear parts
- Incoming material checks
03Benefits and what it detects
- Fast and inexpensive
- Indicates heat treatment condition
- Portable options
- Correlates approximately with tensile strength
04Limitations
- Surface preparation needed
- Conversions between scales are approximate
- Portable methods sensitive to geometry and mass
- Local measurement only
- Not a substitute for tensile testing where specified
05Specifying and reviewing the method
Specify method and scale, load, locations, number of readings and acceptance range. For welds in sour service, Vickers HV10 traverses according to the project or NACE MR0175/ISO 15156 requirements are typical.
Other references: ISO 6506 (Brinell), ISO 6508 (Rockwell), ISO 6507 (Vickers), ISO 16859 (Leeb), ISO 18265 (conversions)