Influence of brazing parameters on the microstructure and mechanical properties of stainless steel sandwich joints

One of the methods of joining the plates to each other is brazing in which the joining is done under vacuum, pressure and high temperature. In this study, copper filler was used due to its low cost, low melting temperature and relatively good bond strength compared to other fillers such as silver or nickel. The two layers and five layers sandwich joining has been investigated under the influence of air atmosphere and high vacuum. Optical images were taken from the samples to examine the microstructure of the joint after metallography and electroetch .Which showed that in the bond did not form any oxides or harmful phases at the vacuum atmosphere and the bond was completely uniform and without cavities. Also, microhardness test were used to investigate the mechanical properties of the joint. The hardness of the joints in the air atmosphere samples was higher than the high vacuum atmosphere samples due to the formation of hard phases , the highest hardness in the high vacuum sample was 100 Vickers.