An experimental study to predict the exposure time for microwave based joining of different grades of stainless steel material

The process of joining the different metals has been used from earlier times termed as 'welding'. Now a day's microwave joining is gaining so much popularity because of its inherent advantages such as eco-friendly, economical, fewer defects and impurities when compared to other conventional welding processes (like MIG, TIG and arc welding). Many materials such as Inconel, EN 31, stainless steel (SS), aluminum, mild steel (MS), ceramics, composite materials, etc. can be processed for different operations under microwave energy. Among all the listed materials, stainless steel (SS) is mostly used. The SS grades such as SS202, SS304, SS316, SS409, etc. are mostly used for various engineering applications. The Microwave joining process is mainly carried out by using two processes such as hybrid carbon microwave joining (HCMJ) and selective hybrid carbon microwave joining (SHCMJ). Both processes have a direct effect on the exposure time. By using hit and trial method the exposure time to join the metals can be determined in both the cases. In this paper, SHCMJ process is used to join SS202-SS202, SS304-SS304, and SS316-SS316 materials. The joining is carried out by using 99.9% pure nickel-based powder as an interface material, having a particle size of 20 μm. To predict the exposure time of microwave joining, the experimental testing is carried out on a number of SS samples. It is observed from this study that the exposure/joining time depends upon the number of factors such as the grade of SS material, its sample size, the grade of refractory bricks, the position of the cavity (vertical-cavity), etc. In this paper, the exact/approximate exposure time is proposed for different grade of SS material (SS202-SS202, SS304-SS304, and SS316-SS316) under similar working conditions.