Vacuum brazing of mild steel using eutectic CuSil brazing alloy

Need for joining similar and dissimilar materials with various thickness and geometry increasing rapidly, inferable from their bit of leeway of light-weighting in the automobile and aviation industries. Brazing is such method expanding quickly with the approach of reasonable high-temperature furnaces incorporated with high vacuum systems. Negligible distortion and restraint of thermal stresses with steady heating and cooling rates make this procedure amiable for joining materials of different size and thickness. In the present study, mild steel brazing was carried out in butt and lap joint configurations using a foil composed of CuSil eutectic (72%Ag28%Cu) to check for reliability in piping and automotive components. Brazing process was performed with varying overlap for lap joints, and butt joint at a constant temperature of 835 degrees C in a vacuum furnace. Microstructure and elemental composition of the joints were examined using Optical microscope, SEM and EDS. Mechanical properties were investigated at the joint region using micro hardness and tensile strength at room temperature. Results showed that microstructure composed of eutectic Ag and Cu microstructure with no signs of porosity and cracks in the brazed joint. The average hardness of 95 HV in the brazed region is less when compared to the base metal of average hardness 135 HV. It has been found that due to more brazing area, failure occurred away from joints in lap joint configuration, and in brazing joint in case of butt configuration due to micropores and voids. (c) 2020 Elsevier Ltd. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advances in Materials and Manufacturing Applications.