Hardness Test Introduction
The hardness test is a mechanical test for material properties used in engineering design, structural analysis, and material development. Hardness is defined as a material’s resistance to permanent deformation such as indentation, wear, abrasion, and scratch. The primary goal of the hardness test is to determine the suitability of a material for a specific application or treatment to which it has been subjected.
Hardness test is currently divided into two categories: Macro Hardness Test and Micro Hardness Test. Macro hardness testing is typically performed on larger specimens and can provide valuable information about the bulk properties of a material. However, it may not be as precise as micro hardness testing, which uses smaller loads and indenters to evaluate the properties of a material at a smaller scale.
Macro Hardness Test
1. Brinell hardness tester: The Brinell hardness tester uses a hardened steel ball as the indenter and applies a load of up to 3000 kgf (kilogram-force). The resulting indentation is measured and the hardness is calculated based on the load and the diameter of the indentation.
2. Rockwell hardness tester: The Rockwell hardness tester uses either a diamond cone or a hardened steel ball as the indenter and applies loads between 15 kgf and 150 kgf. The depth of the resulting indentation is measured and the hardness is calculated based on the depth and the applied load.
3. Vickers hardness tester: The Vickers hardness tester uses a diamond pyramid as the indenter and applies loads between 1 gf (gram-force) and 120 kgf. The resulting indentation is measured and the hardness is calculated based on the load and the surface area of the indentation.
4. Knoop hardness tester: The Knoop hardness tester uses a rhombic-based pyramid as the indenter and applies loads between 10 gf and 1000 gf. The resulting indentation is measured and the hardness is calculated based on the load and the projected area of the indentation.
Micro Hardness Test
1. Vickers micro hardness tester: The Vickers microhardness tester uses a diamond pyramid as the indenter and applies loads between 1 gf (gram-force) and 1 kgf. The resulting indentation is measured and the hardness is calculated based on the load and the surface area of the indentation.
2. Knoop microhardness tester: The Knoop microhardness tester uses a rhombic-based pyramid as the indenter and applies loads between 10 gf and 1000 gf. The resulting indentation is measured and the hardness is calculated based on the load and the projected area of the indentation.
3. Martens hardness tester: The Martens hardness tester uses a sharp diamond point as the indenter and applies loads between 0.1 gf and 1 kgf. The resulting indentation is measured and the hardness is calculated based on the load and the depth of the indentation.
