Mechanical and fracture analysis of welded pearlitic rail steels

Abstract

Welding rail steels using gas metal arc welding shows promise for repairing railhead defects. Finite element analysis was performed on the rail before and during the welding process. It was revealed that the sizes of the heat affected zone (HAZ) and fusion zone would be approximately 15mm and 5mm respectively. Hardness tests showed that the parent material is harder than both the HAZ and the welded region. The parent steel has ultimate strength, yield strength, and elongation to failure of 1114MPa, 624MPa, and 11.1% respectively. These values are higher than those of the welded rail steel. The average KI for the parent specimen was 70MPa·m0.5, while for the welded steel it was 54MPa·m0.5. The pearlitic steel displayed ductile fracture features immediately ahead of the crack tip but approaching the end of the fracture surface the failure mechanism became less ductile. The welded rail steel in contrast consists of ductile features throughout the entire fracture surface. © 2010. Journal of Mechanics of Materials and Structures.