Joining austenitic (304) and ferritic (430) stainless steels by diffusion welding using copper interlayer

Stainless steel materials are a type of material that is frequently used in many areas such as automotive parts, biomedical instruments, kitchenware, heat exchangers, nuclear power plants, space and aviation. Stainless steels are preferred because of their resistance to corrosion (rusting), their ability to work in different temperature ranges, their longevity and ease of production. Among the stainless steel materials, austenitic (AISI 304) and ferritic stainless steel (AISI 430) materials are the two types with the most usage network in the industry. Austenitic stainless steels are frequently preferred due to their surface quality, good corrosion resistance, high strength and good weldability. Another frequently used stainless steel group is ferritic stainless steels. Compared to austenitic stainless steels, it has lower costs and higher corrosion resistance. In addition, ferritic stainless steels have the property of being magnetized. In this study, austenitic stainless steel (AISI 304) and ferritic stainless steel (AISI 430) materials were joined by diffusion welding technique using a 200 μm thick copper foil interlayer. The diffusion source was combined in an argon gas atmosphere at temperatures of 960, 980 and 1000°C, for 45, 60 and 75 minutes. Microhardness and tensile tests were applied to determine the mechanical strength of the materials. In addition, variance (Anova) analyzes were performed with the Taguchi optimization method in the experiments, and the most effective parameters were found and the reliability level of the experiment was determined. When the hardness values were examined, it was measured as 279 HV on the 430 stainless steel side in the combined sample at a temperature of 1000°C with a waiting time of 75 minutes. The highest hardness value in the cross-sectional region was measured as 125 HV in the sample at the same temperature and time. When the tensile test was performed on all samples, it was observed that the tensile strength increased with increasing temperature and waiting times. The highest tensile strength was measured as 491.582 MPa in the sample at 75 minutes and 1000°C temperature. In addition, seamless weld joints were observed in all samples.