铝合金的搅拌摩擦焊接工艺研究

【作者】 阿荣；

【导师】 王希靖；

【作者基本信息】 兰州理工大学 ， 材料加工工程， 2004， 硕士

【摘要】 搅拌摩擦焊接(FSW)是由英国剑桥焊接研究(TWI)所于1991年发明的一种固相连接方法，由于其在汽车及航空工业中较为重要的地位，FSW现已经成为一项很重要的焊接技术。在这种焊接过程中，一个旋转的摩擦头在两个对接的板材表面之间移动并最终可对板材进行连接。本课题通过对试验用不同厚度的材料，如不同厚度的铝合金LY12、 L2及LF2进行焊接后的每个接头进行成型特点、微观组织及接头力学性能等的研究，总结出摩擦搅拌焊接过程中焊接规范参数，主要包括摩擦头旋转速度、焊接速度及焊接摩擦加热功率等对焊接接头质量的影响规律。通过上述研究，不仅可以得出对应不同焊接材料的一组理想的焊接规范参数而且也可以得到上述各种规范对焊接接头质量影响的大致规律：(1) 转速对接头的影响：接头强度随着转速的增加，先增加后减小，板厚越大，强度增加越不明显；焊核区平均硬度随转速增加而下降；而焊核区晶粒尺寸随着转速的增加先下降后上升。(2) 焊速的影响：接头强度随着焊速的增加而减小；焊核区平均硬度随焊速的增加而上升；随焊速变化，焊核区晶粒尺寸变大。(3) 摩擦加热功率的影响：接头强度随着摩擦加热功率的增加而先增加后减小；而焊核区硬度和焊核区晶粒尺寸均随着摩擦加热功率的增加而先减小后增加。本课题实验结果不仅对FSW焊接试验提供数据基础，而且也可为今后的摩擦搅拌焊接工艺研究提供了参考。更多还原

【Abstract】 Friction Stir Welding (FSW) is a solid state welding method developed by TWI in the 1990s,and as well as an important new welding technique with potentially significant application in automotive and aerospace industry. In this welding process, a rotating welding tool is driven into the material at the interface of, for example, two adjoining plates, and then translated along the interface.The object of this research was to investigate the characteristics of joining, microstructures and mechanical properties of FSW joints welded for experimental aluminum alloys, such as LY12, L2, and LF2 with different thickness and the influence of welding parameters including most importantly the tool’s rotational speed, welding velocity, and welding energy on the quality of joint according to the solid-state joining principle during FSW welding. Finally, the optimal welding parameters for different materials under experimental condition were completed on the basis of correlative studies. Furthermore, roles of the influences of welding parameters on welding joints were established: (1) influence of rotational speed on joint: strength of joint will increase firstly, then decrease; the average value of hardness in weld nugget could fall; microstructure could be fine and then bigger with the increase of rotational speed.(2) influence of welding velocity: strength of joint will decrease while the value of hardness in weld nugget and microstructural dimension will enhance with the increase of welding velocity.(3)influence of welding energy: variation of joint strength was in accordance with the role of with rotational speed whereas the value of hardness in weld nugget and microstructural dimension are contrary to the result above.The results of investigations not only provide data for FSW welding experiment, but also can support the further study of techniques of FSW method.更多还原