Hardness value
The hardness test value indicates how hard a material is. It is determined by the force and size of the indentation applied to the material.
Physical-chemical mechanism of action
The hardness test value measures how much force is required to leave a solid indentation in the material. This value gives an indication of how well the material resists mechanical stress.
Metallurgical relevance & risks in welding
A too high hardness test value can lead to crack-sensitive microstructures, especially when it comes to martensite. This can cause fractures and failure of the weld joint. Conversely, a too low hardness test value can lead to softer, less tough material, resulting in deformation and lower strength.
Workshop practice & action instructions
To determine the hardness test value correctly, use standardized test methods such as Brinell or Rockwell hardness testers. The exact force and size of the indentation must be adhered to according to the manufacturer's instructions. In welding, it is important to check the hardness test values before and after the process to ensure no unwanted changes have occurred.