Strain hardening exponent
The strain hardening exponent is a value from the tensile test that describes the increase in flow stress during plastic deformation. It shows the material's behavior under dislocations.
Physical-Chemical Mechanism of Action
The hardening exponent (n) describes how much the flow stress of a material increases when it is plastically deformed. It is a measure of the rate of dislocations in the crystal structure.
Metallurgical Relevance & Risks in Welding
A high hardening exponent means that the material quickly hardens and loses its plasticity. This can lead to hot cracks or fractures if the weld is not cooled properly.
Workshop Practice & Instructions
When welding steels with a high hardening exponent (e.g., martensite), careful cooling is essential. The cooling time should be set so that the structure does not cool too quickly (t8/5 > 25 s) to avoid hot cracks.