Fracture Surface Investigations of Api Pipes Welded With Parameters Determined By Taguchi Method

Abstract

In this study, SEM images of the samples taken from welded nick break tests of API 5L X65 pipe joints, whose welding parameters were determined by Taguchi method, were examined. As a result of the investigations, the elongations and orientations exhibited by the grains showed that ductile and brittle fractures were observed in the welded joints. As it was observed from equiaxed, honeycomb like images that the fractures exhibited a ductile behavior. Brittle fractures that occurred due to cleavage breaks in some regions were detected. An apparent effect of welding direction was observed in fracture behavior. It was detected from the SEM images that a ductile fracture structure had occurred in all joints that were performed from bottom to top, while it was observed in the joints performed from top to bottom that generally cleavage planes had developed along with fibrous structures in places, therefore brittle fractures had occurred.

Effect of Shop-Primer Coating on S235JR Steel on MAG Weldability

“…As the enlarged spaces coalesce, a crack forms, and the material breaks. The ductile fracture of the S235JR sample subjected to plastic deformation has been described in the literature [18][19][20][21][22]. Depending on the chosen method, sandblasting and increased shop primer coating thickness in the samples welded with robotic MAG did not affect the results of the tensile test although they affected the welding quality.…”