【作者】 周利；

【导师】 刘会杰；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2006， 硕士

【摘要】 搅拌摩擦焊(Friction Stir Welding,以下简称FSW)是一种新型固相连接技术,目前已被广泛用于Al、Mg等低熔点材料的连接,并在航空航天、造船、交通运输等部门获得大规模应用。鉴于FSW技术的优点,近年来国外研究者开始对高熔点材料的FSW技术开展研究,而我国目前基本上还未见有相关报导。高熔点材料FSW技术最为关键的部分是焊具设计,由于焊具寿命的原因,高熔点材料FSW技术尚处于研究阶段。本研究针对高熔点材料开展FSW焊具设计工作,采用硬质合金作为搅拌头材料,在结构上采用分体式设计。建立了搅拌摩擦焊过程中搅拌针的承载模型,在此基础上进行焊具设计并根据试验结果进行改进。工艺试验结果表明焊具设计对焊接过程很大影响,必须设计结构尺寸合适的焊具才能实现高熔点材料的连接。采用经过改进的锥状搅拌针焊具能成功实现T3紫铜合金的焊接,焊接2m后焊搅拌头基本没有出现磨损和变形。在氩气保护下能实现304不锈钢的焊接,但搅拌头长时间处于高温时会出现变形及严重磨损。本研究建立了FSW过程中热源有限元分析模型,使用商用有限元分析软件Marc对焊接过程中工件和搅拌头的温度进行了模拟。模拟结果表明铜合金焊接时温度相对较低,而304不锈钢和TC4钛合金焊接时搅拌头最高温度在1100oC以上。对于304不锈钢和TC4钛合金而言,为了保证焊接过程正常进行,必须采用强制冷却措施。更多还原

【Abstract】 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.更多还原