Study on the effect of nano SiC on the properties of friction stir welded joints of magnesium alloy
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摘要: 为提高AZ31镁合金焊接接头的综合性能,文章分别研究了无纳米SiC-1道次、添加纳米SiC-1道次和SiC-4道次的搅拌摩擦焊焊接接头,通过光学显微镜、显微硬度仪和拉伸试验机分析了焊接接头的微观组织与力学性能;利用电化学工作站研究了接头的腐蚀行为,采用扫描电镜、EDS和XRD分析了接头的腐蚀形貌、元素成分和物相组成。结果表明,搅拌摩擦焊焊接接头成形良好、无缺陷;接头焊核区组织为均匀的等轴状晶粒,焊接道次的增加可有效改善SiC颗粒的分布情况,异质形核位点的存在起到了晶粒细化的作用,提高了接头的力学性能;在3.5% NaCl溶液腐蚀试验中,含SiC颗粒的接头耐腐蚀性能提升,其中SiC-4道次的接头耐腐蚀性能最佳。Abstract: In order to improve the comprehensive performance of AZ31 magnesium alloy welded joints, the friction stir welded joints without nano-SiC-1 pass and with nano-SiC-1 pass and 4 passes were studied respectively. The microstructure and mechanical properties of the welded joints were analyzed by optical microscope, microhardness tester and tensile testing machine. The corrosion behavior of the joints was studied by electrochemical workstation. The corrosion morphology, element composition and phase composition of the joints were analyzed by scanning electron microscopy, EDS and XRD. The results show that the friction stir welding joint is well formed and has no defects. The microstructure of the weld nugget zone of the joint is uniform equiaxed grains. The increase of welding passes can effectively improve the distribution of SiC particles. The existence of heterogeneous nucleation sites plays a role in grain refinement and improves the mechanical properties of the joint. In the 3.5% NaCl solution corrosion test, the corrosion resistance of the joint containing SiC particles is improved, and the corrosion resistance of the SiC-4 pass joint is the best.
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Key words:
- nano-SiC /
- friction stir welding /
- microstructure /
- mechanical properties /
- electrochemical corrosion
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表 1 AZ31镁合金化学成分表
元素 质量分数/(%) 元素 质量分数/(%) Al 3.240 Fe 0.002 0 Zn 0.790 Cu 0.003 8 Mn 0.329 Ni 0.001 2 Ce 0.150 Be 0.000 9 Si 0.032 Mg 余量 表 2 搅拌摩擦焊焊接参数
参数 试样1 试样2 试样3 填充材料 无 SiC颗粒 SiC颗粒 焊接道次 1 1 4 转速/(r/min) 1600 1600 1600 焊接速度/(mm/min) 80 80 80 轴肩下压量/mm 0.2 0.2 0.2 焊接倾角/(°) 3 3 3 表 3 极化曲线拟合参数
试样 自腐蚀电流密度
Icorr/(10−6A/cm2)自腐蚀电位
Ecorr/V无SiC-1道次 6.59 −1.414 添加SiC-1道次 1.28 −1.397 添加SiC-4道次 1.14 −1.214 -
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