| 摘要: |
| 研究了SPF/DBTi-6Al-4V合金及其激光焊接接头静态拉伸性能和疲劳性能,并获得S-N曲线.通过观察组织特征和疲劳断口形貌,分析了激光焊接对SPF/DBTi-6Al-4V合金疲劳性能的影响.结果表明,SPF/DBTi-6Al-4V合金激光焊接接头的抗拉强度略低于母材抗拉强度,而疲劳强度明显低于母材疲劳强度,约为其抗拉强度的40%.SPF/DBTi-6Al-4V合金组织为α+β等轴细晶组织,其焊接接头组织为含α,针状马氏体α'和少量β相的魏氏组织结构.焊接接头组织结构的不均匀性,以及组织的粗大化是导致激光焊接接头疲劳性能下降的重要原因.SPF/DBTi-6Al-4V合金疲劳断裂为塑性断裂,其焊接接头疲劳断裂为准解理断裂,这显著降低激光焊接接头的疲劳性能.而焊接气孔等焊缝表层微小几何不连续缺陷的存在往往成为激光焊接接头疲劳断裂的裂纹源。 |
| 关键词: 钛合金 超塑性成形/扩散连接 激光焊接 疲劳性能 |
| DOI： |
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| Influences of laser welding on fatigue propertis of SPF/DB Ti-6Al-4V alloy |
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YAO Wei, GONG Shuili
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National Key Laboratory For High Energy Density Beam Processing Technology, Beijing Aeronautical Manufacturing Technology Research Institute, Beijing 100024, China
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| Abstract: |
| Tensile and fatigue properties of SPF/DB titanium alloy and its laser welded joints were investigated experimentally, and S-N curve was obtained.Microstructure and fatigue fracture features were observed, and influences of laser welding on fatigue properties of SPF/DB Ti-6Al-4V alloy were analyzed.It showed that tensile strength of the laser welded joints of SPF/DB Ti-6Al-4V alloy is less than that of the base metal slightly, but fatigue strength of the laser welded joints, about 40% of its tensile strength, is less than that of the base metal obviously.SPF/DB Ti-6Al-4V alloy is composed of equiaxed structure with αand β phases, and its laser welded joints are composed of weave structure with α, acicular martensiteα' and β phases.Uniformal and coarse microstructure is an important factor causing decrease of fatigue properties of laser welded joints.The fracture of SPF/DB Ti-6Al-4V alloy is plastic failure, but the welded joints are quasi-cleavage fracture which decreases fatigue properties obviously.At the same time the minute flaws below the surface of weld are usually the origin of fatigue failure of laser welded joints. |
| Key words: titanium alloy SPF/DB laser welding fatigue properties |
