Indentation spacing
The indentation spacing is the minimum distance between adjacent test indentations or from the specimen edge, to prevent mutual work-hardening effects. This spacing is essential for valid hardness values.
Physical-Chemical Mechanism of Action
Work hardening is a phenomenon where metals harden at the surface due to rapid cooling, affecting their mechanical properties. Too small an indentation spacing can cause work-hardening effects to overlap and reduce the metal's resistance.
Metallurgical Relevance & Risks in Welding
Too small an indentation spacing can lead to inaccurate or inconsistent hardness values. This can cause cracks, distortion, and reduced service life of components. Additionally, it can lead to failed tests, compromising the safety of the entire system.
Workshop Practice & Instructions
For metals like steel and nickel, DIN EN 10204 specifies that the indentation spacing must be at least 3 mm. For other materials or specific test methods, this value may vary. It is important to follow the applicable standards and adhere to the spacing exactly to ensure reliable hardness values.