Characterization of Metallurgical Defects in the Melt Zone of 304L Steel Tubes Manufactured by GTAW Process

摘要

This study consisted of the characterization of longitudinal cracking pattern observed in weld joint in the manufacture of 304L steel pipelines with thin wall thickness by GTAW process. These tubes are used in food and automotive industries. The cracks grown in the liquid-solid interdendritic zones at high temperatures. It was found that the cracks are associated with change on solidification mode and presence of the holes produced by shrinkage. The change in the solidification mode was associated with the presence of second phase particles. The results suggest that the formation of cracks is promoted by increasing current during the welding although the heat input is constant.