两种TIG焊工艺对LD10接头力学性能的影响

Effect of two different TIG welding processes on mechanical properties of LD10 aluminum alloy joint

关键词:  LD10铝合金  TIG焊  焊接热循环  力学性能

Key words:  LD10CS aluminum alloy  TIG welding  welding thermal cycle  mechanical properties

摘要:

对5.5 mm厚度的LD10(2A14-T6)铝合金进行了两种工艺的TIG焊接,采用热电偶测定了接头的热循环曲线,分析了不同工艺对接头力学性能的影响.结果表明,两面三层焊热影响区中同一点先后经历三次热循环,导致过时效区硬度大幅下降,拉伸时断裂于此;焊缝区各层所经历的热过程不同,导致其硬度起伏较大.与两面三层焊相比,单面两层焊有更高的抗拉强度,为358.3 MPa,热影响区范围窄,且过时效区硬度比三层焊时高,但焊缝中气孔和晶界网状分布的第二相的存在使焊缝和接头的塑性相对降低.

Abstract:

5.5 mm thick LD10CS (2014-T6) aluminum alloy plates were TIG welded with two different processes,and the welding thermal cycle was measured by thermocouples. The effect of thermal cycle on microstructure and mechanical properties of the two joints was analyzed by optical microscopy,microhardness test and tensile test. Since the heat affected zone in the two-sided three layers welding joint undergone three thermal cycles, resulting in the hardness of the over aging zone drop significantly and tensile fracture occurred there. While each layer in the weld area experienced different thermal processes,leading to the hardness fluctuation seriously. Compared with the two-sided three layers welding,the joint of single-sided two layers welding has higher tensile strength,which is 358.3 MPa,and the width of the HAZ is narrower and the hardness in the over aging zone is higher than three layers welding joint. But due to the existing of pores and network-like distribution of secondary phase along the grain boundaries,the plasticity of the joint decreases.