Influence of forging pressure and welding time on microstructure and mechanical properties of dissimilar metal friction welding joints between AISI-316 austenitic stainless steel and AISI-4140 alloy steel under high speed rotation

Abstract

Friction welding is a process of connecting metals without fusion or namely is solid state process, where the welding process occurs as a result of friction through the merger between the rotation speeds of one of the rotating workpieces. This research is concerned with studying the forging pressures and welding times of the microstructure and mechanical properties of a dissimilar metal weldment between AISI-316 austenitic stainless steel and AISI-4140 alloy steel. Forging pressure variations used 110 kg/cm2, 130 kg/cm2 and 150 kg/cm2, while the welding time variations used were 35 seconds, 50 seconds and 65 seconds. Friction welding had operates with a high speed rotation of 1800 rpm. The results of the study showed that the increased variation in forging pressure and welding time resulted in a reduction in the specimen length, due to the lubrication process in the welding joints of the two materials. The results of the microstructure are seen grain coarsened occurs in the HAZ region the shape and size of the grain is different when compared to the parent metal. The mean hardness of the welding area interface is 332 HVN. The hardness value is lower than the hardness of the AISI-4140 parent metal, but it is higher than the AISI-316 parent metal. The hardness value of the AISI-4140 parent metal material is 354.7 HVN. While the parent metal material AISI-316 averages 183.5 HVN. The optimal tensile strength value is produced at a variation of forging pressure 130 kg/cm2 of variation of friction time of 35 seconds with a value of 455.02 N/ mm2.