The welding quality of aluminum alloy using MIG welding depends on expert welder’s technique which is reflecting their knowledge and experiences. And it is important to extract and share the expert welder’s technique to keep welding quality. However, it is quite difficult for expert welder to initiate their excellent welding technique into younger welder because their judgement process of welding expert during welding is too intuitive to explain. On the other hand, Analytic Hierarchy Process (AHP) has been used to analyze decision-making process for human being such as consumer and spcialist, etc. We adopt this AHP approach and analyze decision making process of expert welders to perform good welding of aluminum alloy. We extracted technical skill from 10 expert welders of aluminum alloy, and showed that their priority regarding welding defect and their tuning tendency of welding parameter using AHP method. This approach would be applicable for obtaining the technical indication of good quality of welds by the feedback of analytical results.
Vacuum free self fusion solidification bonding of aluminum with copper insert metal was investigated. Self fusion solidification bonding process by reaction diffusion showed isothermal fusion and isothermal solidification in the bond at 893 K below a melting point of aluminum. Dendrite of α phase of aluminum was observed on the facture surface at the initial stage of the bonding process and the dimple pattern from solid α phase was observed at the final stage. Joint strength was decreased by formation of brittle Al2Cu and Alcu at the middle stage. The bonding condition with high bonding pressure, high heating rate and smooth initial surface roughness increased the joint strength. These bonding parameters decreased the thickness of the oxide film formed during the bonding process. Deformation of the bonding interface caused fracture of the oxide film as the barrier for reaction diffusion. Thickness of the oxide film increased with thick copper insert metal. However, it increased deformation of the bonding interface and the joint strength.