AZ91D镁合金电阻点焊显微组织及裂纹分析
Analysis on Microstructure and Cracks of AZ91D Alloy Joint Produced by Resistance Spot Welding
黄万群1, 许敬年1, 谷立娟2, 郑丽明3
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作者单位：（1. 中国石油大学（华东） 机电工程学院, 山东 东营 257061; 2. 睿能（四平）北方能源技术有限公司, 吉林 四平 136001;3.一汽铸造有限公司 有色铸造分公司, 吉林 长春130062）
中文关键字：AZ91D镁合金； 电阻点焊； 显微组织； 裂纹
英文关键字：AZ91D alloy; resistance spot welding; microstructure; cracks
中文摘要：对1.5 mm厚的AZ91D镁合金板进行交流电阻点焊，采用无水乙醇、肥皂水、水对AZ91D镁合金进行抛光，研究了其点焊接头的显微组织及显微硬度分布。结果表明，采用无水乙醇抛光时，镁合金显微组织清晰度最好，肥皂水抛光时次之，水抛光时则较前两者模糊；点焊接头由熔核区、热影响区及母材区组成；由熔核中心、热影响区至两侧母材，显微硬度先降低后又升高，以熔核中心为对称轴，两侧显微硬度近似对称分布；在熔核内发现结晶裂纹。
英文摘要：AZ91D alloy plate with 1.5 mm thickness was joined by resistance spot welding. The alloy was polished by ethanol, soapsuds and water, respectively. The microstructure and microhardness of the alloy joint was studied. The results indicate that among these polishing solutions, ethanol has the best effects, while soapsuds take the second place, when water is used as polishing solution, the microstructure is vaguer than the former two. The AZ91D spot welded joint consists of nugget zone, heat effected zone and base metal zone. From nugget center, heat effected zone to the two base metals, the microhardness firstly decreases, then increases and symmetrically distributes in the nugget center. Inside the nugget zone, solidification cracks are found.