부산대학교 도서관

The microstructure, mechanical strength, and fatigue response of metal active gas (MAG) butt‐welded G20Mn5 cast steel was thoroughly investigated for exploring the service safety and reliability of new‐generation railway bogie frames. The fatigue properties of the matrix and welded joints were determined by both low‐ and high‐cycle service regimes. On the basis of nanoindentation testing, the fatigue crack growth (FCG) was derived by correlating with cyclic plastic response of microdomain materials across the MAG joint. The results show that the MAG induces considerable changes in microstructures and hardness of the G20Mn5 matrix and resultantly produces an overmatching welded joint but show comparatively low‐ and high‐cycle fatigue properties to as‐received material. The calculated threshold FCG range based on the Murakami model indicates that the maximum 1.5‐mm defect might be the cracking site subjected to fatigue loading from the structural integrity viewpoint. [ABSTRACT FROM AUTHOR]