# Hardness testing (HT)

> Hardness testing (HT) measures a material's resistance to indentation or rebound; in inspection work it verifies heat treatment, post-weld heat treatment and heat-affected-zone hardness limits set by codes such as NACE MR0175.

- Source: https://amps.global/glossary/hardness-testing/
- Type: Glossary
- Published: 2026-09-05
- Tags: NDT, hardness testing, materials

## Key facts

- Laboratory scales: Brinell (HB), Rockwell (HRC, HRB), Vickers (HV); portable methods: Leeb rebound (ASTM A956) and UCI (ASTM A1038)
- Typical field use: weld cap and HAZ checks after PWHT, sour-service limits (for example 22 HRC / 248 HV), verifying delivered material grade
- Surface preparation and part mass strongly affect portable readings; conversions between scales follow ASTM E140
- Testers are calibrated against certified reference blocks

Also known as: HT, portable hardness testing, Leeb, UCI.

## How it works

A defined indenter is pressed into the surface under a defined load and the indentation is measured (Brinell, Vickers), the depth is read (Rockwell), or a rebound velocity or resonance shift is converted to hardness (Leeb, UCI). Portable testers make on-site verification of welds and pressure equipment practical.

## Where it is used

Verification of heat treatment and PWHT, sour-service compliance in oil and gas, material identification alongside PMI, and failure investigations.

## HT in AMPS

Tester calibration certificates and reference block certificates sit on the AMPS equipment page with expiry flags. In AMPS, reports are produced from your own Microsoft Word templates through the template engine: job data such as the client, purchase order number, equipment serial numbers, location and dates is filled in automatically, an AI assistant can tidy the wording, the report can be signed in AMPS, and the finished Word file is saved in the job's report folder in your OneDrive, SharePoint or Google Drive.

## Related pages

- [Positive material identification (PMI)](https://amps.global/glossary/positive-material-identification/)
- [Calibration certificate](https://amps.global/glossary/calibration-certificate/)
- [Reference block](https://amps.global/glossary/reference-block/)

## Sources

- [Hardness on Wikipedia](https://en.wikipedia.org/wiki/Hardness)
- [Rockwell scale on Wikipedia](https://en.wikipedia.org/wiki/Rockwell_scale)