7050铝合金锻板点状缺陷原因分析  

Analysis on the Causes of Point Shaped Defects in 7050 Aluminum Alloy Forged Plate

作　　者：王玉玲 曹善鹏 孙有政 王萍[3] 王俊 WANG Yu-ling;CAO Shan-peng;SUN You-zheng;WANG Ping;WANG Jun(Shandong Nanshan Aluminum Co.,Ltd.,Shandong Yantai 265713,China;Shandong Nanshan Science and Technology Research Institute Co.,Ltd.,Shandong Yantai 265713,China;Yantai Nanshan University,Shandong Yantai 265713,China;Hang Xin Material Technology Co.,Ltd.,Shandong Yantai 265713,China)

机构地区：[1]山东南山铝业股份有限公司,山东烟台265713 [2]山东南山科学技术研究院有限公司,山东烟台265713 [3]烟台南山学院,山东烟台265713 [4]航鑫材料科技有限公司,山东烟台265713

出　　处：《失效分析与预防》2024年第2期122-126,共5页Failure Analysis and Prevention

摘　　要：7050铝合金锻板在沿厚度方向的超声波检测时发现点状缺陷,采用金相检查、扫描电镜和能谱仪检测等方法对缺陷产生原因进行分析。结果表明:点状缺陷为内部小裂纹,裂纹断口为沿晶脆性断口,晶界表面存在大量的Al_(2)CuMg和Ti-Zr-Al三元合金相。由于Al-Zr中间合金中部分Al_(3)Zr相尺寸偏大,Al-Ti中间合金加入时机不合适,导致锻板所用的铸锭在熔炼过程中大尺寸的Al_(3)Zr相未完全溶解,与后加入的Ti元素生成粗大的高熔点Ti-Zr-Al三元合金相,并在局部偏聚。这种局部富集缺陷在铸锭组织中保留,显著降低合金塑性,使局部区域变脆。在锻造过程中,脆化的三元合金相在锻造载荷作用下发生开裂。此外,晶界密集分布的细小Al_(2)CuMg相以及7050铝合金在高温下的晶界结合力较弱也是导致局部区域沿晶开裂的重要原因。The point-shaped defects were found in the 7050 aluminum alloy forged plate through the ultrasonic testing along the thickness direction.The metallographic examinations,scanning electron microscopy analyses,and energy dispersive spectroscopy analyses were performed to investigate the cause of the defects.The results indicate that point shaped defects are internal small cracks.The fracture surface of the crack is a brittle intergranular fracture,with a large amount of Al_(2)CuMg and Ti-Zr-Al ternary alloy phases on the grain boundary surface.Analyses suggests that due to the existence of Al_(3)Zr phases with large size in the Al-Zr intermediate alloy and the inappropriate addition time of the Al-Ti intermediate alloy,the large Al_(3)Zr phases in the ingots for forged plates were not completely dissolved during the melting process,and the coarse Ti-Zr-Al ternary alloy phases with high melting point were formed with the later added Ti element and segregated locally.This locally enriched defect was retained in the ingot structure,significantly reducing the alloy’s plasticity and making the local area brittle.During the forging process,the brittle ternary alloy phase cracked under forging load.The dense distribution of small Al_(2)CuMg phases at grain boundaries and the weak grain boundary bonding force of 7050 aluminum alloy at high temperatures were also important reasons for local intergranular cracking.

关 键 词：锻板 中间合金 沿晶脆性断口 三元合金相 Al_(2)CuMg 失效分析 

分 类 号：TG146.21[一般工业技术—材料科学与工程]