Microstructure and Mechanical Properties of AA 6082/AISI 304 Joints Brazed Using Al-Ge-Si Filler Metal

Abstract

Joining aluminum alloys with stainless steel is of great importance in many industrial sectors. Due to the low solidus temperatures of high-strength aluminum alloys, brazing with commercially available filler metals is not possible. Al-Ge-Si filler metals with a lower melting temperature of about 490 °C allow these alloys to be joined. They are manufactured in the form of foil via ultrafast solidification. AA 6082/AISI 304 joints are produced via induction brazing and vacuum furnace brazing. In this study, the tensile shear strength and the fatigue behavior of joints are investigated. Joints produced via induction brazing reached a maximum joining strength of 53 MPa, while vacuum-brazed joints achieved a maximum of 20 MPa. The fracture occurs in the reaction zone, especially inside the Al7Fe2(Si,Cr) intermetallic layer. The results of the fatigue tests show that the joints produced via induction brazing achieved 1 × 107 cycles at a stress amplitude of 7 MPa. Vacuum-brazed joints reached this at a stress amplitude of 3 MPa. All fatigue-tested samples fail in the reaction zone. The high hardness and growth of the SiGe solid solution and the Al7Fe2(Si,Cr) intermetallic layer had a major influence on the joining strength and fatigue behavior of AA 6082/AISI 304-brazed joints.