Characterization of high-carbon high-chromium tool steel/low-carbon steel friction-welded joints for industrial tooling applications

Abstract

High-carbon high-chromium steel (D3) is commonly used for making cutting tools. It possesses higher abrasion resistance and higher degree of dimensional stability in heat treatment. It is high resistant to softening and medium resistant to decarburizing and can be nitrided. In addition to the use as cutting tools, they may be used as spindles, dies, sand blast nozzles, etc. In almost all such applications, friction welding is effectively implemented in welding of D3 steel with low-carbon steel, in order to reduce cost and enhance ductility. Mechanical testing is carried out to analyze the joint integrity and strength of D3 steel/low-carbon steel joints. Tensile strength was observed as 341.742 MPa, which is comparable to the tensile strengths of both the parent metals. Micro-hardness variation across the welded joint is found using Vickers hardness tester. Increase in micro-hardness is found in the D3 steel side 2 mm away from the weld interface. This is due to fully plasticized intermetallic compound formed near the interface, which is brittle in nature. Interfacial regions of the friction-welded joints were studied microscopically. Micrographs have been obtained using optical microscope and scanning electron microscope to study the bonding mechanism. Axial shortening, which is the result of flash formation by transfer of mass from the central region of joint, was also studied during the experimentation.