Shape optimization for tool wear in the friction-stir welding of cast Al359-20% SiC MMC

Tool wear in the friction-stir welding of AI359 + 20% SiC MMC produced a self-optimized shape which when achieved resulted in excellent welds and no additional tool wear. This optimized tool shape was slightly different at weld speeds of 6 and 9 mm/s. Tool wear rate was observed to decrease linearly and to effectively cease above about 11 mm/s weld speed. There was some attrition or comminution of larger SiC particles during welding but the weld zones were very homogeneous in terms of SiC distribution between the base metal and the friction-stir weld zone. There was no weld-related degradation and the weld zone hardness was 30% higher than the base. (C) 2002 Kluwer Academic Publishers.