Kovuustesti

Kovuustesti, or hardness testing, is a set of methods used to determine a material’s resistance to deformation by indentation. The test yields a numerical hardness value that helps characterize mechanical properties, compare materials, verify heat treatment, and support material selection in engineering and manufacturing.

Most common hardness tests include Rockwell, Brinell, and Vickers, each using a different indenter and a range of test loads. Rockwell tests employ a diamond or steel indenter and measure the depth of an indentation after applying a preliminary load followed by a main load. Brinell testing uses a hardened steel or ceramic ball and measures the diameter of the impression. Vickers testing uses a diamond pyramid indenter and measures the diagonals of the resulting imprint. Microhardness tests, such as Knoop and Vickers with low loads, are used for small or thin samples and for evaluating microstructures.

Procedure generally involves preparing a flat, clean surface, applying a preload to settle the contact, applying the main load for a specified dwell time, then removing the load and measuring the impression with optical means. The measured dimension is converted into a hardness value (for example, HV for Vickers, HB for Brinell, HRC/HRA/HRT for Rockwell) according to standardized formulas.

Hardness correlates with wear resistance and strength but is not a complete material property by itself; factors such as heat treatment, microstructure, and anisotropy can influence results. Hardness testing is widely used in quality control, material development, and failure analysis, while being sensitive to surface finish and sample geometry.