Effect of Friction Welding Parameters on the Mechanical and Microstructural Properties of Dissimilar IN713C-AISI 4140 Joints

The aim of this study is to investigate the effects of the parameters such as friction pressure, friction time, forging pressure and forging time on mechanical and metallurgical properties of friction welded joints of inconel 713C and AISI 4140 material pair. Tensile tests and hardness tests were carried out to determine the mechanical properties of welded joints. Following tensile tests, the fracture surfaces occurred in the joints were examined by scanning electron microscope (SEM), and the type of fracture and fracture surface characteristics were evaluated. Optical microscope and electron microscope were used to examine the metallurgical properties of welded joints. The tensile, hardness, and microstructure results were associated with the welding process parameters. It was concluded that the highest strength was obtained as 718 N/mm(2) and there was a significant increase in hardness values in the thermomechanically affected zone (fully deformed zone) of all samples. In all welding tests, it was determined that the fracture location was on the side of AISI 4140 steel material. As a result of friction welded joints, while gamma and gamma '-Ni-3(Al, Ti) phases were observed in the matrix, the formation of the gamma ''-Ni3Nb phase at the grain boundaries was also determined by SEM-EDS analysis. Also it was shown that the carbides deposited at the grain boundaries are generally carbides formed by Nb.