Martensite finish temperature
The martensite finish temperature is the point at which the martensitic transformation is complete. Below this temperature, the structure no longer changes.
Physical-Chemical Mechanism of Action
The martensite finish temperature is the endpoint of the martensitic transformation, at which the metal has transformed its structure into glass-hard martensite. This process occurs through rapid cooling and the strengthening of carbon in the steel matrix.
Metallurgical Relevance & Welding Risks
When the material is cooled below the martensite finish temperature, it stays softer and loses its hardness. This can lead to cracks and low toughness. However, cooling too fast can result in glass-hard martensite, which makes the weld prone to cracking.
Shop Practice & Action Guidelines
To ensure an optimal weld, it is important that the material is cooled near the martensite finish temperature. This means the cooling steps must be carefully controlled and monitored. The exact temperature depends on the steel used and the desired microstructure.