Creep-Fatigue Interaction Factor for Welded Joints
The creep-fatigue interaction factor indicates how much a weld is stressed under thermal-mechanical alternating load and high temperature. It helps estimate the lifetime of the joint.
Physical-Chemical Mechanism of Action
The Creep-Fatigue Interaction Factor (KEIF) describes the damage that occurs at the weld seam due to the repeated interaction of mechanical fatigue and thermal creep. At high temperatures, materials can slowly deform, which, combined with mechanical loads, leads to accumulated deterioration.
Metallurgical Relevance & Risks in Welding
A high KEIF indicates an increased susceptibility to creep and fatigue phenomena. This can lead to long-term deformation of the weld seam and possibly to cracks, especially at rising temperatures and high mechanical loads. The service life of the welded joint is thereby significantly reduced.
Workshop Practice & Action Guidelines
To minimize the KEIF, it is important to design the weld seam so that it operates under minimal mechanical loads and in a stable temperature range. This can be achieved through optimized component design, selection of suitable materials, and careful cooling of the weld seam. At high temperatures, it is especially important that the weld seam microstructure remains stable and does not form glass-hard phases like martensite, which are susceptible to creep.