The effects of isothermal soaking time on the mechanical properties of AA3003 cladded with AA4045 alloy

¹ Advanced Materials Division, MINTEK, South Africa
² Department of Material Science and Metallurgical Engineering, University of Pretoria, South Africa
³ Hulamin Operations Proprietary Limited, Moses Mabhida Road, Pietermaritzburg, South Africa

^* Corresponding author: josephm@mintek.co.za

Abstract

In this study, the effects of the simulated isothermal soaking time on the mechanical properties of AA3003mod cladded with AA-4045 alloy (9031-H24 tube stock) used for automotive heat exchangers were investigated. The high-strength 4045/3003mod clad sheets were fabricated by the roll bonding process and further cold-rolled down to the thickness of 0.3 mm. Intermediate annealing (IA) was conducted during cold rolling at 270~350°C. The tensile test was performed with the clad sheets before and after brazing heat treatment. The fractographs of tensile-test specimens were analysed using scanning electron microscopy (SEM). The effect of soaking time on the mechanical properties of the cold rolled and annealed (CRA), and brazed alloy are presented. Amongst all the samples soaked at different times, cold-rolled and annealed (CRA) specimens showed a higher yield strength of 167MPa and UTS of 276 MPa than the brazed specimens. Post brazing UTS remained in the range of 90 to 152 MPa. The tensile and yield strength of samples preheat treated at 505°C for longer residence times of 40 hrs, then cold rolled and annealed was found to be on the lower end of the 9031-H24 specification. The fracture morphology of the CRA specimen was dominantly dimple fracture, typical of ductile fracture.