Fatigue Crack Growth Studies on Narrow Gap Pipe Welds of Austenitic Stainless Steel Material

The objective of the present study is to understand the Fatigue Crack Growth (FCG) behavior in austenitic stainless steel pipe welds. The tests have been carried out on Compact Tension (CT) specimens machined from the actual narrow gap pipe welds. The notch was located in Weld Centre Line (WCL), Heat Affected Zone (HAZ), HAZ-Fusion Line (FL) interface and the parent metal. The comparisons have been made for the FCG rate for different locations of the crack. The tests were carried out using standard procedure of ASTM E647. The results of FCG rate of narrow gap welds (HAZ, WCL, HAZ-FL interface and parent material) have been compared with that of conventional V-groove welds of Shielded Metal Arc Welding (SMAW) process. The comparison shows that the fatigue crack growth resistance of narrow gap welds is better than conventional groove welds. The FCG resistance of weld and parent material is better than HAZ location in the Paris regime. However, parent material shows superior threshold crack driving force range.