Phase Transformation Residual Stresses
Phase transformation residual stresses arise from volume differences when transitioning from one lattice structure to another, as in martensite formation. They lead to stress regions in the material and can cause cracks.
Physical-Chemical Mechanism of Action
During phase transformation, the atomic arrangement and volume of the material change. For example, in martensite formation in steels, the lattice is strongly compressed, leading to a volume decrease. These changes can create stresses in the material.
Metallurgical Relevance & Welding Risks
These residual stresses can cause cracks in components, especially if not properly balanced. They affect mechanical properties and material life. Improper handling during welding can increase the risk of hot cracking.
Workshop Practice & Action Instructions
To minimize transformation-induced residual stresses, it is important to precisely control cooling rate and weld profile. For steels with high martensite formation, slow cooling (e.g., in a furnace) should be applied to reduce stresses. Temperature control during welding and selection of correct welding materials are crucial.