Effect of Brazing Temperature on Tensile Strength and Microstructure for 304 Stainless Steel Plate-Fin Structure

The vacuum brazing of 304 stainless steel plate fin structure was carried out,and the tensile tests were performed.The scanning electron microscope(SEM) and Energy-dispersive X-ray spectrometer(EDS)tests were carried out to reveal the microstructure and chemical components in the brazed joint.The effect of brazing temperature on tensile strength and microstructure for 304 stainless steel plate-fin structures was discussed.The results show that the tensile strength is increased with the brazing temperature increasing from 1025 to 1100℃.With the brazing temperature increasing,the boron is diffused more adequately,which increases the strength.The microstructure becomes more uniform with the brazing temperature increasing.Hence the brazing temperature is determined at 1100℃.When the brazing temperature is very low(1030℃),more brittle phases are generated in the brazing joint,which decreases the strength.When the brazing temperature is increased to 1100℃,full solid solution is generated in the middle of joint,and the microstructure in the fillet becomes more uniform.