焊丝成分对SiCp/6061Al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 properties of weld metal were investigated with MTS-810 testing system.The results showed that when welding with Al-Mg filler metal,serious reaction between Al matrix and SiC particles occurred in the molten pool,and a quantity of large-size acicular Al₄C₃ formed in the weld metal.With Al-Si filler metal used,the interfacial reaction between Al matrix and SiC particles was alleviated remarkable,only a little small-size acicular Al₄C₃ was tound in the MIG weld,while no acicular Al₄C₃ phase was found in the pulsed-MIG weld.It was also found that Si in welding wire can prevent from the formation of hot-crack in weld.The mechanical testing resuits showed that tensile strengths and elongation of welds deposited with Al-Si filler metal was higher than those of welds deposited with of Al-Mg filler metal.With the same welding wire used,the tensile strength and elongation of welds deposited with pulsed-MIG was high than those of welds deposited with MIG.