To interpret Vickers hardness test results, you must first understand what the numbers mean and how they relate to material properties. Here's a breakdown to help you:
Recognizing the Format
- Hardness Number: This is a numerical value that represents the hardness of the material. Higher numbers indicate greater hardness.
- HV: The Vickers hardness scale is indicated.
- Load (kgf): This is the test load that was used in the measurement. Micro-Vickers tests are typically 10gf to 1kgf, whereas macro-Vickers tests are 5kgf to 30kgf.
Using the Hardness Number to Interpret
- Relative comparison within the sample: A sample's hardness can be compared across different areas of the same sample or between samples subjected to similar conditions.
- Comparison with reference values: Check to see if your material type has established hardness ranges. This enables you to compare your sample to those of others.
- Consider the load: Higher loads may result in slightly lower hardness values due to material deformation. However, the values usually stabilize above 200gf.
Additional Factors
- Test conditions: Ensure that all equipment is properly prepared, tested, and calibrated.
- Reporting format: Additional information, such as indentation size or conversion to other hardness scales, may be included in some reports.
- Material microstructure: The grain size, phase presence, and phase distribution can all influence hardness.