【作者】 葛敬鲁；

【导师】 张钧； 刘建荣；

【作者基本信息】 沈阳大学 ， 材料加工工程， 2011， 硕士

【摘要】 随着科学技术的不断进步,对航空航天飞行器的性能要求越来越高,这就对航空航天材料及其加工技术提出了新的挑战。能够有效减重的连接技术和轻质、高强的新型材料,已经成为人们在材料开发及应用过程中迫切寻求的目标。TC11钛合金作为一种比较成熟的钛合金材料已经应用于制造航空发动机的鼓筒、压气机盘、叶片、飞机结构件等重量轻、可靠性强的结构。电子束焊接技术作为目前多种焊接工艺中最成熟的高能束流加工方法之一,是航空航天飞行器构件的有效连接方法。本课题以TC11钛合金电子束焊接接头为研究对象,研究了TC11合金电子束焊接接头的显微组织、显微硬度分布以及室温拉伸变形行为,并测定了焊接接头试样及母材试样的高、低周疲劳等性能,为TC11钛合金及电子束焊接技术在航天航空领域的推广应用提供数据支持,并得出以下结论：焊接接头熔合区形成的针状马氏体组织提高了接头的硬度,原位拉伸结果显示拉伸过程中应变局部化及断裂位置都在靠近母材的区域。接头母材部分先于熔合区部分进入屈服阶段,熔合区变形与否取决于母材的应变硬化程度,基体合金应变硬化能力的增加有望改善接头整体性能。通过对TC11电子束焊接接头及母材样品的高周疲劳、低周疲劳实验,得出了焊接接头及母材样品的S-N、ε-N曲线。焊接接头样品疲劳性能与母材相当,接头样品在母材区断裂。裂纹源均在样品表面形核,断裂方式为解理或准解理断裂。进行了纯焊缝试样、纯母材试样和标距段为焊缝熔合区的焊接接头三组板状试样的疲劳实验,和焊接接头样品循环过程中残余应变的累积观察实验。发现接头样品在高应力疲劳实验中,塑性变形在焊接接头母材区累积,焊接接头熔合区、热影响区和母材区三个区域的材料基于应力疲劳的相对强弱为：熔合区>热影响区>母材区。电子束焊接接头性能良好,焊接接头具有不低于母材的拉伸、持久、高周疲劳、低周疲劳性能。更多还原

【Abstract】 The performance of aerospace vehicles have become increasingly demanding with the continuous progress of science and technology. There are new challenges in aerospace materials and the process technology. The connection technology effectively losing weight, the new materials of light weight and super-strength have become the urgent objective in the process of developing and applying materials. TC11 titanium alloy has widely used in light weight and reliable structure, such as drum of engine, compressor dish, blade, aircraft structures and so on. As one of the developed high-energy beam machining methods among various welding process, the electron beam welding technology is an effective connectivity method for aviation aircraft component. TC11 titanium alloy joints by electron-beam welding method are the research objects in the present work. The TC11 alloy joints have been investigated in terms of microstructure, micro-hardness distribution and room-temperature pre-tension deformation behavior. Moreover, we have measured the performances of the welded joints and base metal including high and low cycle fatigues. The results provide data support for the application and dissemination of TC11 titanium alloy and electron beam welding technology in aerospace field. The following conclusions have been obtained:Acicular martensite microstructure formed in the region of welding joint bond improved the hardness of joints. The In-situ tensile results showed that both localization and fracture position happened at the field near the side of base metal in the process of tensile strain. The base metal part yields before fusion area. Deformation of fusion area depended on the strain-hardening degree of base metal, so increasing ability of alloy’s strain-hardening were expected to improve overall performance of the joints.S-N andε-N curves were obtained through high cycle fatigue and low cycle fatigue of TC11 electron beam welding joints and base metal. The fatigue property of welding joints was similar to that of base metal and joints cracked in the base metal zone. The fatigue cracks initiated on the surface of specimens. Fracture were cleavage and quasi-cleavage facets. Three fatigue experiments of pure weld specimens, pure base metal and welding joints of gauge segment as weld fusion zone were achieved. Residual strain accumulation in the circulation process of welding joints was observed. At high stress levels and plastic deformation of joints accumulated in base metal zone. The relative strength index based on stress fatigue was: weld fusion zone>heat-affected zone>base metal zone.The performance of electron beam welding joint was not less than that of base metal in tensile, durable, high and low cycle fatigue properties.更多还原