钛合金与铜、钢异种金属焊接性研究

发布时间：2018-02-14 02:07

本文关键词： 电子束焊接异种金属焊接偏束量脆性金属间化合物　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：本文主要对TC4钛合金与T2紫铜的电子束焊接工艺进行了研究,对电子束焊接工艺参数进行了前期调试,探究了不同的电子束偏束量对接头力学性能的影响,对电子束偏铜焊接接头界面相组成进行了研究分析,并且进一步研究了添加钛侧邻焊工艺和添加铜侧邻焊工艺电子束焊接接头界面相组成和力学性能;同时也探索了添加紫铜过渡层的TC4-304SS电子束和摩擦焊接工艺。研究获得了合适的焊接工艺参数为:加速电压60kV,电子束流45mA,聚焦电流680mA,焊接速度lOmm/s,并在此条件下调整不同电子束偏束量进行焊接,试验结果表明,随着电子束偏束量的增加接头抗拉强度先增加,后减小。电子束偏铜焊接接头被分为钛合金侧面积非常小的树枝晶区、铜侧大面积的枝晶区和夹在它们之间的最后凝固区。在铜-肽界面近TC4钛合金处形成一层宽度约39μm的反应层,反应层中大部分区域为富铜区,靠近钛侧极薄的一层为金属间化合物层。整个焊接过程中,Ti元素的扩散距离为23μm,在最靠近TC4钛合金内侧的区域为CuTi相,除此之外还存在CuTi_2、Cu_4Ti、Cu_2Ti、Cu_3Ti和Ti_3Cu_4相。接头强度为162MPa,为脆性断裂,断口内存在大量的CuTi相。研究结果表明,添加钛侧邻焊工艺后,在反应层内靠近钛合金的区域,枝晶的形态和生长方向都有了很大的变化,之前依附于钛合金基体向着第一道焊接熔池生长的枝晶几乎都不存在了,枝晶依附于最后凝固区域的前沿形核并向着第二道焊接熔池的方向生长,直到未熔钛合金的边缘,形成了新的界面形态。在不同的偏束距离下,添加邻焊工艺的电子束焊接接头抗拉强度为210MPa,断口内主要存在CuTi_2相;添加铜侧邻焊工艺的接头抗拉强度为84MPa。钛-钢焊接工艺试验结果显示,不添加中间过渡段时难以获得钛合金与钢的有效连接,采用电子束先焊接钛合金与铜,切割预留出2cm宽的紫铜过渡段,再将其与钢焊接,接头强度可以达到196MPa;添加的铜片厚度为0.5mm时,随着摩擦时间的增加,接头的抗拉强度先增大后减少,抗拉强度最高达到178MPa。断裂发生在钛-铜界面,在界面处主要存在CuTi相。
[Abstract]:In this paper, the electron beam welding process between TC4 titanium alloy and T2 copper is studied, the parameters of electron beam welding are debugged, and the effect of different beam deflection on the mechanical properties of the joint is investigated. The interface phase composition of electron beam bias copper welding joint is analyzed, and the interface phase composition and mechanical properties of electron beam welding joint by adding titanium side welding technology and adding copper side adjacent welding process are studied. At the same time, the TC4-304SS electron beam and friction welding technology with the addition of copper transition layer were explored. The suitable welding parameters were obtained as follows: acceleration voltage 60kV, electron beam current 45mA, focusing current 680mA, welding speed lOmm / s, and adjusting under these conditions. Welding with different beam deviations, The experimental results show that the tensile strength of the joint increases first and then decreases with the increase of beam beam deviation. The welded joint is divided into dendritic regions with very small side area of titanium alloy. A large area of dendritic zone on the copper side and the final solidification zone between them formed a reaction layer of about 39 渭 m in width near the TC4 titanium alloy at the copper-peptide interface, and most of the reaction layers were copper-rich. The extremely thin layer near the titanium side is intermetallic compound layer. The diffusion distance of Ti element is 23 渭 m during the whole welding process. In the region closest to the inner side of TC4 titanium alloy, there is CuTi phase. In addition, there are CuTi2Che Cu2TiTiTiCu3Ti and Ti_3Cu_4 phases. The strength of the joint is 162MPA, which is brittle fracture. There are a large number of CuTi phases in the fracture surface. The results show that the dendrite morphology and growth direction change greatly in the region near the titanium alloy in the reaction layer after adding titanium side welding technology. Almost none of the dendrites attached to the substrate of the titanium alloy to the first weld pool are present. The dendrites are attached to the front nucleation of the final solidification region and grow towards the second weld pool until the edge of the unmelted titanium alloy. A new interface morphology was formed. The tensile strength of the electron beam welded joints with the addition of adjacent welding process was 210 MPA, and the main CuTi_2 phase existed in the fracture surface. The tensile strength of the joint with the addition of copper side adjacent welding process is 84 MPA. The results of welding process test show that it is difficult to obtain the effective connection between titanium alloy and steel without adding intermediate transition section, and the electron beam is used to weld titanium alloy and copper first. The copper transition section with a width of 2 cm is reserved and welded with steel. The strength of the joint can reach 196MPa. When the thickness of the added copper sheet is 0.5 mm, the tensile strength of the joint increases first and then decreases with the increase of friction time. The tensile strength is up to 178 MPA. The fracture occurs at the interface between Ti and Cu, and the CuTi phase exists mainly at the interface.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.1

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