이(異)두께 알루미늄 합금 Al5052 마찰교반용접 시 툴의 두께 방향 틸팅각에 따른 용접성 및 성형성 평가

Abstract

Recently, the need for eco-friendly vehicle is revealed due to environmental and fuel-efficiency regulations. However, eco-friendly vehicle is 200~300kg more heavier than existing vehicle, so light-weight is essential. Currently, in order to realizw vehicle weight reduction, lightweight materials such as aluminium alloys, magnesum alloys and CFRP are applied to the vehicle body. In addition, the Tailor Welded Blanks(TWB) process of aluminium alloys is increasingly applied in the automotive industries because of its high strength to weight ratio, excellent corrosion resistance and crash worthiness. The welds produced by FSW have high strength and formability because they can obtain a sound joint at a relatively low temperature as compared with conventional fusion welding.

This study has the purpose to investigate the applicability of different thickness aluminium alloys by friction stir welding to vehicle body and to secure reliability. 2.5t(Retreating side) and 1.5t(Advancing side) aluminium alloy wokrpeice is used in this study. The mechanical and metallurgical characteristics of the welds by workpeice tilting angle are studied.

As a result of experimental, the highest tensile strength around 225 MPa (fractured of base metal) is achieved at a Y-axis tilting angle 1°. But, workpeice is non welded up to bottom surface at Y-axis tilting angle 0°. As a result of Numerical analysis, a wider thermal distribution was showen at Y-axis tilting angle 1°, because the heat input was more given that the thickness difference was reduced.