Semi-narrow gap 맞대기 용접부에서 피로강도 향상을 위한 펄스GMAW 공정개발

Abstract

The problem occurred that the Fatigue strength has been dropped substantially in the changing course of existing welding joint groove from R4 to R3 in order to improve the productivity of the Semi-narrow gap Butt welds area in hydraulic cylinder tube. In this study, the stable Pulse Gas metal arc welding (GMAW) process has been developed using the wire Φ1.4mm from the CW process using the existing wire Φ1.2mm in order to improve this problem. It has been designed to expand the bead gradually by forming the welding bead and the slope using 50% of this welding current of the start current when the arc start and the tack welding are done in order to prevent the defect in the arc start area and the tack welding area easy to occur the defect. Therefore, the process decreasing the deviation of Fatigue strength to remove the defect part sufficiently by remelting the area designed by the low current has been established. The stable Pulse Gas metal arc welding (GMAW) process has been established to make the Fatigue strength equals or superiors to R4 groove by changing the length and Root face of Notch area in the R3 groove of welding joint and by mitigating the increase of degree of hardness of welding metal by decreasing the melting rate in the part of SM45C.