Strain-Induced Martensite
Deformation martensite is a metastable martensitic phase that forms through plastic deformation of high-alloy austenites or highly formable steels at room temperature. It has higher hardness and grain refinement than conventional martensite.
Physical-chemical mechanism of action
Strain-induced martensite forms from plastic deformation of high-alloy austenite or highly formable steels at room temperature. This process leads to rapid, irregular formation of martensite with increased grain size and hardness.
Metallurgical relevance & welding risks
Strain-induced martensite can form if post-weld heat treatment is missing or insufficient, leading to increased hardness and lower formability. This can cause cracks and fracture in the weld. Additionally, higher hardness can affect the material's structure and reduce its mechanical properties.
Shop practice & action instructions
To avoid strain-induced martensite, proper post-weld heat treatment is essential. This includes tempering or re-austenitizing through heat treatment. The exact temperature and time for these processes must be strictly followed. For high-alloy steels, a minimum hardness of 450 HB (Rockwell) is recommended to avoid strain-induced martensite.