TC4钛合金微束等离子弧堆焊工艺参数对接头的影响

发布时间：2018-03-10 02:04

本文选题：微束等离子弧堆焊　切入点：TC4钛合金　出处：《中国民航大学》2015年硕士论文　论文类型：学位论文

【摘要】：本文研究了焊接工艺参数对不同板厚TC4钛合金微束等离子弧堆焊接头成型的影响规律,结果表明焊接电流和送丝速度对接头成型影响较大,对不同板厚的影响规律相同;枪距对接头成型影响较小,对不同板厚的影响规律存在较大差异,对于窄板,随枪距的增大,堆焊层高度增大宽度减小;对于宽板,随枪距增大,堆焊层高度减小宽度增大。在本实验焊接工艺下,焊缝外部为单向生长α′相马氏体长针,而焊缝内部为网篮组织。热影响区主要由α′相、初生α相和β相组成,热影响区组织分布具有差异性,靠近母材区域晶粒相对细小且α′相针状马氏体含量少。焊缝内部还会出现团束组织和块状α相等特殊组织。随着焊接电流的增大,焊缝外部的马氏体长针逐渐粗大,内部针状α′相马氏体逐渐呈多向杂乱分布,同时焊缝内部β柱状晶尺寸变大;增大送丝速度,焊缝内部马氏体长针数量减少,β柱状晶减少;枪距对于焊缝内部组织的变化影响较小。焊接工艺参数对焊缝内部相组成变化影响较小,焊缝内部均为大量α′相和少量β相。焊接试样显微硬度值由焊缝-热影响区-母材依次降低,焊接工艺对接头硬度值影响较小。焊接接头抗拉强度高于或等于母材,焊缝区脆性较大,塑性比母材差,但强度高于母材。焊缝区的断裂韧性相比于母材较差。去应力热处理工艺对焊接接头的组织和相组成影响较小;对接头硬度有一定的改善作用,降低了部分区域过高的硬度值;经过热处理的试件拉伸断口位置与未经热处理的试件存在差别,未经热处理的试件断裂位置距离焊缝较近;热处理对试件的断裂韧性影响不明显。
[Abstract]:In this paper, the influence of welding process parameters on the forming of TC4 titanium alloy surfacing joints with different plate thickness is studied. The results show that the welding current and wire feeding speed have great influence on the joint forming, and the effects on different plate thickness are the same. The influence of gun distance on joint forming is small, and the influence law of different plate thickness is different. For narrow plate, the width of surfacing layer height decreases with the increase of gun distance, while for wide plate, it increases with gun distance. The height of the surfacing layer decreases and the width increases. In this experimental welding process, the outside of the weld is a long pin of 伪 'phase martensite, while the inner part of the weld is a basket structure. The heat affected zone is mainly composed of 伪' phase, primary 伪 phase and 尾 phase, and the heat affected zone is mainly composed of 伪 'phase, primary 伪 phase and 尾 phase. The microstructure distribution of the heat-affected zone is different, the grain is relatively small near the base metal and the content of 伪 '-phase acicular martensite is less. There will also be a special structure of cluster structure and block 伪 inside the weld seam. With the increase of welding current, The martensite long needle outside the weld gradually became coarse, and the internal 伪 '-phase martensite gradually distributed in a multi-direction disorder, and the size of 尾 columnar crystal in the weld increased, and the number of martensite long needles decreased and the 尾 columnar crystal decreased with the increase of wire feeding speed. The influence of the gun distance on the internal structure of the weld is small, and the welding process parameters have little effect on the change of the internal phase composition of the weld. The microhardness of welding specimens decreased from weld to heat affected zone to base metal in turn, and the welding process had little effect on the hardness of joint. The tensile strength of welded joint was higher than or equal to that of base metal. The weld zone is brittleness, the plasticity is worse than the base metal, but the strength is higher than the base metal. The fracture toughness of the weld zone is worse than that of the base metal. The effect of stress free heat treatment on the microstructure and phase composition of the welded joint is less. It can improve the hardness of the joint and decrease the hardness value of some regions, the tensile fracture position of the heat-treated specimen is different from that of the non-heat-treated specimen, and the fracture position of the unheat-treated specimen is closer to the weld seam. The effect of heat treatment on fracture toughness is not obvious.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.1

【相似文献】