Sn、Bi对Al-Mg-Si合金切削性能的影响

Cutting Performance of Al-Mg-Si Alloy

通过对3种Al-Mg-Si合金棒材切屑形状、加工面表面质量及切削缠刀情况的对比试验,评价了添加Sn、Bi对Al-Mg-Si合金切削性能的影响。采用XRD、SEM,研究了Sn、Bi在Al-Mg-Si合金中的存在形式,提出了Sn、Bi对合金切削性能的影响机制。结果表明,Al-Mg-Si合金中添加Sn、Bi后形成的Mg2Sn、Mg3Bi2及单质Sn等低熔点相在高速切削时受热软化,使切屑脆断;低速切削时这些低熔点相的变形率与基体金属不同,导致形成空洞或裂纹使切屑断裂,从而改善合金的切削性能。复合添加Sn、Bi的Al-Mg-Si合金切削性能最佳。

Effects of Sn and Bi addition on cutting performance of Al-Mg-Si alloy were investigated by comparing the chipping shape, surface roughness and tangle cutter condition in process of cutting of three kinds of Al-Mg-Si-(Sn, Bi) alloys. The existing forms of Sn and Bi in the Al-Mg-Si alloys were observed to understand their ralein cutting performance of alloy by XRD (X-ray diffraction) and SEM (scanning electron microscope). The results reveal that formed Mg2Sn, Mg3Bi or Sn phase in Al-Mg-Si alloy can result in the brittle crack of chip as a result of softening during high speed cutting process, while they can form cavity or crack to result in chip fracture due to deformed rate different from matrix during low velocity cutting process, improving the cutting performance of the alloy. In addition, cutting performance of Al-Mg-Si alloy with mixed Sn and Bi addition is superior to that of ones with only Sn or Bi addition.