Effect of deviation of welding parameters on mechanical properties of X80 steel girth weld

Abstract

Tensile tests were carried out on X80 steel girth welds with four different parameters (no deviation of welding parameters, inadequate number of welding layers, inadequate preheating temperature and inadequate interpass temperature) under automatic welding technology. The strain distribution behavior, strain hardening law and the influence of welding parameter deviation on mechanical properties were studied during tensile deformation. The results show that the strain localization occurs at the interface of the weld filler layer when the preheating temperature of the weld is inadequate and the interpass temperature of the weld is inadequate, and the strain localization occurs at the maximum thickness of the filler layer when the number of welding layers is inadequate. The deviation of welding parameters significantly reduces the strength of girth weld. The yield strength and tensile strength are the lowest when the interpass temperature is inadequate. When the interpass temperature is inadequate, the strain hardening ability deteriorates rapidly. When there is no deviation of welding parameters, the fracture is dimple shaped, which is typical ductile fracture. When the welding parameters deviate, the fracture of the girth weld is a mixed fracture of toughness and brittleness; When the number of welding layers is inadequate, it is mainly brittle fracture; When preheating temperature and interpass temperature are inadequate, ductile fracture is the main mechanism.