| Friction stir welding (FSW) is a new solid state joining method, which has been commercialized for joining low melting point materials (LMS) such as Al and Mg alloys in the aerospace, marine, and transportation industries. Due to the benefits of this technology, researchers aboard have began to study the feasibility of welding high melting poing materials (HMS) using FSW, while little reports have been seen in China. The most important part of FSW for HMS is the design of welding tools, until now FSW for HMS has just been in experimental stage because of poor tool life.This paper designed tools used in friction stir welding for HMS, hard alloy was choosed as tool material and adopted the devided tool design. On the base of establishment of the loads model on pin during FSW process, this paper designed tools and made adjustments according to the experimental results.The experiment results indicated that tool design directly influences the welding process, HMS could be joined only if proper tool pattern was designed. T3 copper was successfully welded using the revised cone pin tool, no evident tool wear and deformation was observed when 2 metres of weld was finished. 304 stainless steel was successfully joined under Argon protection, but the pin tool would present deformation and severe wear when worked at high temperature for a long time.This paper estabalished the FEM analysis model of the heat source during FSW process , commercial FEM analysis software Marc was choosed to simulate the temperature distribution of the specimen and tool during FSW process. The results indicated that the temperature was relatively low when copper was welded, while for 304 stainless steel and Ti-6Al-4V the highest temperature of the pin tool was above 1100oC. As for 304 stainless steel and Ti-6Al-4V,forced cooling measure must be adopted in order to make the welding process proceed normally.
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