Suppressing Aluminum Carbide in Welding Aluminum Silicon Carbide Composite

Abstract

Weldability of aluminum-based metal matrix composite A359/SiC/10p using gas tungsten arc welding and R356.0 filler material is investigated. The welding current, welding speed, and preheat temperature affect the weld quality significantly. Finite element analysis is successfully applied to map the weldment temperature during preheating and welding. During mechanical testing of welded specimens, a crack propagates in the parent composite or in the weld, but not in the stronger zone between the weld and the parent material. The weld region contains reasonably uniform distribution of SiC particles due to high viscosity of the molten weld and its fast cooling rate. Proper control of heat input and addition of silicon-rich filler material hinder the interface reaction between aluminum matrix and the reinforcing SiC particles, and successfully suppresses the formation of harmful aluminum carbide flakes in the weld. The average tensile and flexural strengths of optimally welded specimens approach those of the parent composite while its ductility exceeds that of the parent material.