Effect of Forging Pressure on Evolution of Microstructure and Tensile Properties of Rotary Friction-Welded Shaft-to-Plate Joints of Dissimilar Low-Carbon-Grade C22 and C15 Steels

This study intends to investigate the effect of forging pressure (20, 26 and 32 MPa) on microstructure and tensile properties of rotary friction-welded (RFW) shaft-to-plate joints of dissimilar AISI 1020 (C22) and AISI 1018 (C15) steels, respectively. The joints fabricated using the forging pressure of 26 MPa showed greater tensile strength of 452 ± 22.6 MPa, yield strength of 362 ± 18.1 MPa, elongation of 10.1 ± 0.51% and weld interface hardness of 247 ± 7.41 HV. The superior tensile properties of joints fabricated at forging pressure of 26 MPa is primarily because of the optimal plastic deformation of joining surfaces and heat input leading to better coalescence of welding surfaces, evolution of finer bainitic structure in fully deformed zone of joints and less grain growth in heat-affected zone. The fractured tensile specimens of joints showed the characteristics of finer and deeper dimples and microvoids.