Martensite tempering stage
Martensite tempering stage is the range during tempering of steels where carbon precipitates as epsilon carbide. This leads to a glass-hard structure with high stress resistance.
Physical-Chemical Mechanism of Action
When tempering steels, carbon is released from the supersaturated solution and forms epsilon carbide. This process occurs in the martensite tempering stage, which is triggered by rapid cooling (t8/5 < 5 s).
Metallurgical Relevance & Welding Risks
Too rapid cooling can lead to a martensitic structure. This is glass-hard and causes cracks, especially hot cracks. The tendency for degradation of mechanical properties increases significantly.
Shop Practice & Action Guidelines
To minimize risks, control the cooling rate. For steels with high carbon content (e.g., HSS), slow cooling (t8/5 > 25 s) is recommended. Use a suitable cooling medium, such as water or oil.