Two-stage martensitic transformation
Two-stage martensitic transformation: Under high loads and rapid cooling, an intermediate phase forms first, which later transforms into martensite. This causes heavily distorted microstructures.
Physicochemical Mechanism of Action
On fast cooling under high load, an intermediate stage forms first, which later transforms into martensite. This transformation takes place diffusionlessly in two steps.
Metallurgical Relevance & Welding Risks
A two-stage martensite transformation can lead to heavily distorted structures that cause a higher susceptibility to cracks and hot cracks. This can occur especially under high loads and fast cooling.
Workshop Practice & Instructions
To minimize the two-stage martensite transformation, the weld should be cooled slowly. This can be done through controlled cooling or the use of cooling jackets. Under high loads it is important that the cooling process does not happen too fast.