The main objective of this investigation is to study the effect of diffusion bonding time on microstructure and mechanical properties of dissimilar Ti6Al4V titanium alloy and AISI 304 austenitic stainless steel joints. The dissimilar joints of Ti6Al4V titanium alloy and AISI 304 steel were developed using the different levels of bonding time (30, 45, 60, 75 and 90 min) in a vacuum chamber at a bonding temperature of 900 °C and compressive pressure of 14 MPa. The microstructure of joints was analyzed using optical microscopy (OM) and scanning electron microscopy (SEM). The elemental analysis of joint interface was studied using the SEM energy dispersive spectroscopy (EDS). The evolution of intermetallic compounds at the joint interface was analyzed using X-ray diffraction (XRD). The ram tensile tests and lap shear tests were performed to assess the bonding strength and lap shear strength of dissimilar joints. Results showed that the dissimilar joints of Ti6Al4V alloy–AISI 304 steel developed using the diffusion bonding time of 75 min showed higher lap shear strength of 151 MPa and bonding strength of 244 MPa due to the better coalescence of the joining surfaces and evolution of optimum width of diffusion region having minimum embrittlement effects.

In this investigation, the effect of holding time on the microstructure of joint interface and bonding strength of vacuum diffusion bonded dissimilar austenitic stainless (ASS) – titanium (Ti) alloy joints were investigated. The dissimilar joints of ASS - Ti alloy were developed using the holding time of 30, 45, 60, 75 and 90 minutes in a vacuum chamber at a temperature of 900⁰C and pressure of 14 MPa. The bonding strength of ASS – Ti alloy joints was evaluated using the ram tensile test. The microhardness survey was done perpendicular to the joint interface. The microstructure of the joint interface was analyzed using optical microscopy (OM). The evolution of intermetallic compounds at the joint interface was analyzed using X-ray diffraction (XRD). The microstructure of the joint interface was correlated to the bonding strength of joints.

High-temperature dissimilar connections built of Inconel 718 and AISI 410 martensitic stainless steel (MSS) are widely used in a range of industries, including boiler construction, the chemical industry, aerospace, and nuclear. When compared to other materials, Inconel 718 and AISI 410 martensitic stainless steel offer superior strength and corrosion resistance under a variety of environmental conditions. The rotational speed was adjusted between 1100 and 1500 RPM, while the friction pressure, friction time, forging pressure, and forging duration were all kept constant during the testing. Five sets of testing were performed, with the resultant tensile strength (both room temperature and hot tensile) and Vickers Hardness being recorded for each set of trials. To assess the structural integrity of the joints, a detailed microstructural investigation, SEM-EDS, and XRD were performed at their interfaces. Mechanical properties were revealed to be high at 1300 RPM due to the small grain size at the interface region; ultimate tensile strength and hardness were determined to be 571 MPa and 423 HV, respectively, due to the small grain size at the interface region. Additionally, a pitting corrosion study has been conducted on dissimilar welded joints at optimum conditions, and their results were discussed and compared with base metals.