Stress-Induced Martensite Formation
The athermal transformation of austenite to martensite caused by mechanical stresses below the conventional start temperature. This can lead to increased hardness and cracking in metastable austenites.
Physicochemical Mechanism of Action
Stress-induced martensite formation happens when metastable austenite is converted into martensite under mechanical load. It occurs without athermal transformation and below the normal martensite start temperature.
Metallurgical Relevance & Welding Risks
This process can lead to higher hardness and cracking in the weld, especially when the mechanical stresses are high. The tendency to hot cracking goes up because martensite has a glass-like hard structure.
Workshop Practice & Instructions
To avoid stress-induced martensite formation, treat the weld so mechanical stresses stay low. You can do this by cooling carefully and using austenites with low metastability.