Dissimilar welds between unreinforced AA6082 and AA6092/SiC/25p composite by pulsed-MIG arc welding using unreinforced filler alloys (Al–5Mg and Al–5Si)

Abstract

Weldability between an unreinforced aluminium alloy (AA6082) and an AA6092/SiC/25p composite, using as filler metals both Al–5Mg (ER5356) and Al–5Si (ER4043) unreinforced alloys, has been studied in the present work. One of the main requirements considered to obtain metallurgical weldability was to reduce at maximum the heat input to limit the possible interfacial reaction among molten aluminium matrix and SiC particles which produces aluminium carbide (Al 4C 3) inside the weld pool and fusion line. For it, welding procedure selected was a gas shielded metal arc welding, working in pulsed current mode (MIG-P), to obtain an improved control of the metal transfer to the molten pool. Three kind of joint designs were used: “I”, “V” and “X”, working with one and two filler metal runs. Mechanical tests of welded joints showed that tensile strengths, for all these welding conditions, were very similar and close to 223 MPa, which is approximately the 65% of the AA6082-T6 one. In all cases, failure was located through the HAZ of the unreinforced alloy. The application of a postwelding heat treatment made possible to recover the 100% of the parent unreinforced alloy tensile strength.