焊丝成分对SiCp/6061 Al复合材料MIG焊焊缝组织及性能的影响

采用Al-Mg及Al-Si两种焊丝分别对SiCp/6061Al复合材料进行了MIG焊及脉冲MIG焊,利用光学显微镜、电子显微镜及MTS-810试验机对焊缝的组织及性能进行了分析.结果表明,采用Al-Mg焊丝焊接时,无论是MIG焊还是脉冲MIG焊,熔池中Al-SiC间的界面反应程度均较大,生成了较多的针状Al4C3,且Al4C3的尺寸较大.采用Al-Si焊丝时,MIG焊熔池中的界面反应程度显著降低,仅生成了少量尺寸较小的针状Al4C3;而采用Al-Si焊丝的脉冲MIG焊焊缝中没有发现针状Al4C3.同时,利用Al-Si焊丝可有效地防止焊缝熄弧处的宏观结晶裂纹.力学性能试验表明,采用同样焊丝时,脉冲MIG焊接头的强度及伸长率比MIG焊接头的高,而用Al-Si焊丝焊接的接头强度比用Al-Mg焊丝焊接的接头强度高.

Effect of composition of welding wire on microstructure and mechanical properties of weld metal in SiC particle reinforced 6061Al matrix composite

The SiC_p/6061 Al alloy composite was welded by usingM1G and pulsed-MIG welding with Al-Si or Al-Mg filler metal. The micro-structure of weld metal was investigated with OM and TEM, and the prop-erties of weld metal were investigated with MTS-810 testing system. Theresults showed that when welding with Al-Mg filler metal,serious reactionbetween Al matrix and SiC particles occurred in the molten pool, and a .quantity of large -size acicular Al_4C_3 formed in the weld metal. With Al-Si filler metal used, the interfacial reaction between Al matrix and SiCparticles was alleviated remarkable, only a little small-size acicular Al_4C_3was tound in the MIG weld, while no acicular Al_4C_3 phase was found inthe pulsed-MIG weld. It was also found that Si in welding wire can pre-vent from the formation of hot-crack in weld. The mechanical testing re-suits showed that tensile strengths and elongation of welds deposited withAl-Si filler metal was higher than those of welds deposited with of Al-Mgfiller metal. With the same welding wire used, the tensile strength and e-longation of welds deposited with pulsed-MIG was high than those ofwelds deposited with MIG.