航天高强铝合金熔焊接头金相的定量分析

发布时间：2018-06-12 12:10

本文选题：2219铝合金 + 焊接接头　；参考：《北京工业大学》2015年硕士论文

【摘要】：在航天高强铝合金焊接结构的制造中,焊接接头是最薄弱的部位。在焊接的热作用下,焊缝的冶金缺陷、接头组织的不均匀等成为固溶强化型铝合金接头综合性能下降的一个重要原因。以往对接头性能的分析和评价大多限于焊接过程中某些因素影响的定性认识,尚缺乏较为完善的定量分析和评定的方法,并用于解释焊接接头的组织、性能与热输入、热循环之间的关系。课题工作的研究内容如下:(1)利用金相图像分析系统对熔焊接头组织进行定量分析与评定,研究焊接热循环与接头最终组织的关系及其金相表征;从而获得对焊接热输入及其热循环特点与焊接接头缺陷生成、组织状态及其与焊接工艺关联性的定量认识。(2)通过对焊接试件断口和焊缝截面进行气孔率、尺度及分布的观测与对比,揭示焊缝微气孔形成位置与分布的规律,通过测量微气孔及其与所在局域的面积比率,提出拟以2%及以上的微气孔率作为接头性能预测和失效分析的一个定量指标。(3)通过观测晶界宽度,对2219固溶型铝合金经熔焊的热循环后强化相脱溶、向晶界析出与聚集的程度等作出定量表达。本文提出的定量分析方法加强了固溶型高强铝合金焊接工艺优化的机理,是对X射线铝合金焊接接头检测与评定方法的一个必要补充,对改善和提升2219及同类高强铝合金的接头性能具有重要的工程应用意义。
[Abstract]:In the manufacture of aerospace high-strength aluminum alloy welding structure, welded joint is the weakest part. The metallurgical defects of the weld and the uneven structure of the joints are one of the important reasons for the deterioration of the comprehensive properties of the solid solution strengthened aluminum alloy joints under the thermal action of welding. In the past, most of the analysis and evaluation of joint properties were limited to the qualitative understanding of the influence of some factors in the welding process, but there was still no perfect quantitative analysis and evaluation method, which was used to explain the microstructure, properties and heat input of welded joints. The relationship between thermal cycles. The contents of the research are as follows: (1) quantitative analysis and evaluation of the microstructure of welded joints are carried out by metallographic image analysis system, and the relationship between welding thermal cycle and final microstructure of welded joints and their metallographic characterization are studied. Thus, the quantitative understanding of welding heat input and heat cycle characteristics and the formation of weld joint defects, microstructure and its correlation with welding process is obtained. The porosity of the fracture surface and the weld section of the welded specimen is obtained. The observation and comparison of the size and distribution reveal the formation and distribution of micropores in welds. By measuring the micropores and their area ratio to the local area, the formation and distribution of micropores in welds are revealed. It is proposed that the microporosity of 2% or more be used as a quantitative index for predicting and failure analysis of joint properties. By observing the grain boundary width, 2219 solid solution aluminum alloy is strengthened by thermal cycling after melting and welding. The degree of precipitation and aggregation to grain boundary was quantitatively expressed. The quantitative analysis method proposed in this paper strengthens the mechanism of welding process optimization of solid solution high strength aluminum alloy and is a necessary supplement to the inspection and evaluation method of X-ray aluminum alloy welding joint. It has important engineering application significance for improving and improving the joint properties of 2219 and similar high strength aluminum alloys.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：V252;V46

【相似文献】