大厚度TA15钛合金板潜弧焊接头的组织及拉伸性能

在添加TA1纯钛中间层填充板的条件下,对64mm厚TA15钛合金板进行潜弧焊接,分析了焊接接头的显微组织、拉伸性能以及焊缝中氢、氧、氮的含量,并与不添加中间层的普通潜弧焊接头的拉伸性能进行了对比。结果表明:添加中间层后焊接接头的焊缝区组织为较大尺寸的柱状晶,晶内分布着不同方向的针状α′相,母材区组织为初生α相和少量β相,热影响区组织中既存在α相,也存在α′相;添加中间层后焊接接头的抗拉强度比普通潜弧焊接头的有所降低,但其塑性显著提高,焊缝中氢、氧、氮的含量比母材中的有所降低。     

链轮焊接裂纹生成的分析

本文采用拉伸和弯曲试验方法，研究了奥氏体焊条焊接ＺＧ４５Ｍｎ２与４０Ｃｒ异种钢焊接接头的力学性能，在用两种不同合金系统的焊条及三种冷却状态下，对熔合区裂纹的产生进行了比较，并对延迟裂纹的氢影响进行了分析。试验表明，两种焊条的接头均接近较低强母材强度；提出了防止裂纹的措施。     

链轮焊接裂纹生成的分析

本文采用拉伸和弯曲试验方法，研究了奥氏体焊条焊接ＺＧ４５Ｍｎ２与４０Ｃｒ异种钢焊接接头的力学性能；在用两种不同合金系统的焊条及三种冷却状态下，对熔合区裂纹的产生进行了比较，并对延迟裂纹的氢影响进行了分析。试验表明，两种焊条的接头均接近较低强母材强度；提出了防止裂纹的措施。     

NiTi形状记忆合金与异种材料激光焊接研究进展

对近年来NiTi形状记忆合金与异种材料(不锈钢和钛合金)激光焊接的研究情况进行了总结分析。由于材料的化学成分差异很大,直接激光焊接在接头中极易生成脆性金属间化合物,使得力学性能严重恶化,限制了异种材料结构的应用。国内外关于优化Ni Ti形状记忆合金与异种材料的激光焊接接头力学性能的方法,主要包括添加中间层和激光偏置两种方法,它们的共同之处是都可以减少脆性金属间化合物生成,不同之处是采用添加中间层的方法在抑制金属间化合物产生的同时会在焊缝中引入新的金属间化合物,接头的力学性能取决于新引入金属间化合物的脆性,脆性低则接头的力学性能更好;另外,中间层的添加量不能过多,否则会恶化力学性能。对于激光偏置焊接法,激光的偏移位置和偏移量至关重要,该方法的优点是可以节省填充材料,但是对于装配精度要求较高。与激光偏置法相比,采用添加中间层的方法,接头的力学性能更好。除了以上两种方法外,焊后热处理也可以改善接头的力学性能。最后提出NiTi形状记忆合金与异种材料激光焊接未来可能的研究方向,旨在为后续研究提供参考与借鉴。     

钼与石墨的瞬间液相扩散焊

借助瞬间液相扩散焊接技术,分别以铬-镍粉、铬-镍-铜压制薄片、锆-镍-钛粉作中间层,于1 650℃下真空保温1 h对钼和石墨进行焊接,对焊接接头进行了剪切试验和微观形貌观察、成分分析.结果表明:钼和石墨在添加以上三种中间层后均可实现焊合,接头有一定强度;其中以锆-镍-钛粉作中间层时所得接头的抗剪强度最大,超过了石墨的抗...     

补焊对5A06铝合金焊接接头力学性能的影响

以5A06铝合金焊接模拟件的一次焊接接头和二次焊接(补焊)接头为研究对象,通过拉伸试验、疲劳试验,以及对疲劳断口形貌观察,研究了补焊对该焊接接头力学性能的影响。结果表明:补焊会造成焊接接头力学性能的下降,其中静强度和中值疲劳强度下降明显;焊缝是接头拉伸强度与疲劳性能的薄弱部位,补焊会造成焊缝附近金属晶粒粗大。     

TC2钛合金焊接接头组织与性能的实验研究

分析了TC2钛合金焊接接头的显微组织结构，并综合焊接接头的显微硬度分布规律以及拉伸试验结果，分析了焊接接头不同区域的性能。结果表明，焊缝区为α α’魏氏组织，热影响区为魏氏α α’ 少量β组织；焊缝区的硬度最高，约高于母材50HV，塑性较差；热影响区的硬度较低，塑性较好，其强度是焊接接头部位的最薄弱区。焊接接头的延伸率比母材低88％，屈服强度略低于母材，极限强度与母材相当。     

基于DIC方法的铝合金焊接接头拉伸性能研究

为准确表征铝合金焊接接头拉伸性能,针对2219铝合金搅拌摩擦焊焊接接头,采用数字图像相关(DIC)方法,测量焊接接头在拉伸载荷作用下的全场应变历程,得到铝合金焊接接头焊接区在拉伸时的连续屈服强度曲线。进而结合材料弹塑性本构模型,拟合焊接区内各点处材料本构关系,并分别构造了铝合金焊接接头焊缝区及热影响区力学性能连续变化的拟合函数,使之可以表达铝合金焊接接头焊接区内任意一点力学性能。最后利用所构造的力学性能函数模拟了铝合金焊接接头的拉伸过程,数值结果与试验相吻合,表明基于数字图像相关法的应变测量可以准确地表征其焊接区内的材料力学性能。     

激光焊接在铜/铝焊接中的应用

铜、铝各自有自身优异的性能,使用激光焊接技术实现两者的快速有效连接,将对汽车制造、航空航天、船舶制造等多行业多领域的发展有积极的意义.通过激光器类型、焊接速度、是否添加中间层等方面概述了改善激光焊接接头的方式,从金相组织角度解释了激光焊接中铜/铝接头断裂的机制.     

缓解陶瓷与金属钎焊接头残余应力的新方法研究

填加中间过渡层是缓解陶瓷与金属钎焊接头残余应力的有效方法。但是在钎焊过程中还存在很多问题。金属泡沫具有显著的能量吸收特性,因此可以用作中间层材料,研究发现采用金属泡沫作为中间层可以有效缓解接头残余应力,并且存在一个最佳的泡沫层厚度。     

Half-transient liquid phase diffusion welding: An approach for diffusion welding of SiCp/A356 with Cu interlayer

Aluminum matrix composite SiC_p/A356 was welded by half-transient liquid Phase diffusion welding (HTLPDW) with a Cu interlayer. The effects of welding parameters and interlayer thickness on the properties of the welded joint were investigated, and the optimal welding parameters were subsequently put forward. The relationship between the tensile strength of the joint and the microstructure was studied by analyzing the microstructure of joint using a scanning electron microscope (SEM) and an electron probe micro-analysis (EPMA). Results confirmed the success of welding aluminum matrix composite SiC_p/A356 utilizing HTLPDW method with a Cu interlayer. Shorter welding time was a prominent characteristic of HTLPDW as compared with conventional transient liquid phase (TLP) diffusion welding. Furthermore, its welded joints had a tensile strength almost 72% of its parent matrix composites, evidently signifying the suitable application of half-transient liquid phase diffusion welding in welding composite engineering structures.     

双层板材平底无铆塑性连接的抗拉强度预测模型

平底无铆塑性连接铆接头的抗拉强度只能通过大量破坏性试验获得,且强度检测成本高、周期较长。重点分析铆接头在拉伸过程中的颈部断裂失效、拉脱失效及混合失效三种失效形式及成因;建立平底无铆塑性连接过程的数值模型,获得铆接头的剖面几何参数,通过铆接头的剖面观测试验验证数值模拟的精确性;借鉴管材拉拔过程中的主应力法,基于铆接头的剖面几何参数建立平底无铆塑性连接抗拉强度预测模型;进一步通过铆接头强度检测试验验证了抗拉强度预测模型的正确性,深入分析底厚值对抗拉强度的影响规律。结果表明,铆接头抗拉强度预测值与试验值最大误差为14.8%,其主要误差来源于铆接头加工硬化系数、摩擦因数、底厚值等参数;铆接头抗拉强度随着底厚值的减小呈递增趋势,当底厚值为0.50 mm时,Al5052-Al5052的抗拉强度最大,铆接头发生混合失效。建立一种高效、低成本的铆接头成形质量评价方式,对平底无铆塑性连接铆接头的几何参数优化具有指导意义。     

无定形塑料激光透射焊接质量分析

通过测试焊接试样的拉伸剪切强度与断口形貌,检验塑料激光透射焊接的质量.阐述了激光焊接塑料的基本原理,选用了无定形的聚碳酸酯材料进行焊接工艺研究,分析了激光参数对焊缝拉伸剪切强度的影响,并采用金相显微镜观察了断口形貌.结果表明:激光塑料焊接可以得到力学性能良好的焊接试样,由于能量密度的不同,焊缝在拉伸剪切力作用下会产生不...     

Investigation on overlap joining of AZ61 magnesium alloy: laser welding, adhesive bonding, and laser weld bonding

This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect.     

Effects of laser shock processing on mechanical properties of laser welded ANSI 304 stainless steel joint

With the rapid development of engineering component with integration,high-speed and multi-parameter,traditional techniques haven’t met practical needs in extreme service environment.Laser welding,a new welding technology,has been widely used.However,it would generate the drop of mechanical properties for laser welded joint due to its thermal effect.Laser shock processing(LSP) is one of the most effective methods to improve the mechanical properties of laser welded ANSI 304 stainless steel joint.In this paper,the effects of LSP on the mechanical properties of laser welded ANSI 304 stainless steel joint have been investigated.The welded joint on the front of the tensile samples is treated by LSP impacts,and the overlapping rate of the laser spot is 50%.The tensile test of the laser welded joint with and without LSP impacts is carried out,and the fracture morphology of the tensile samples is analyzed by scanning electron microscope(SEM).Compared with the yield strength of 11.70 kN,the tensile strength of 37.66 kN,the yield-to-tensile strength ratio of 0.310 7,the elongation of 25.20%,the area reduction of 32.68% and the elastic modulus of 13 063.876 MPa,the corresponding values after LSP impacts are 14.25 kN,38.74 kN,0.367 8,26.58%,42.29% and 14 754.394 MPa,respectively.Through LSP impacts,the increasing ratio of the yield strength and tensile strength are 121.79% and 102.87%,respectively;the elongation and area reduction are improved by 5.48% and 29.38%,respectively.By comparing with coarse fracture surface of the welded joint,the delamination splitting with some cracks in the sharp corner of the welded joint and asymmetric dimples,LSP can cause brighter fracture surface,and finer and more uniform dimples.Finally,the schematic illustration of dimple formation with LSP is clearly described.The proposed research ensures that the LSP technology can clearly improve the yield strength,tensile strength,yield-to-tensile strength ratio,elongation,area reduction and elastic modulus of the welded joint.The enhancement mechanism of LSP on laser welded ANSI 304 stainless steel joint is mainly due to the fact that the refined and uniform dimples effectively delay the fracture of laser welded joints.     

热压对镁合金焊接接头拉伸性能的影响

通过拉伸试验机、光学显微镜、扫描电镜等研究了热压对AZ31B镁合金钨极氩弧焊焊接接头拉伸性能和断口形貌的影响。结果表明:热压后焊接接头的抗拉强度和伸长率分别可达200MPa和10%,比焊态的分别提高了18%和67%;焊态接头拉伸断口以解理断裂为主,呈现出较多的脚印状小平台,同时伴随有少量韧窝;而热压后焊接接头的断口具有平台撕裂畸变现象,可以观察到热压塑性变形流变线,晶界表现出一定的滑动协调现象。     

铍青铜弹簧触指焊接及热处理关键技术研究

采用熔焊技术,通过硬度、抗拉强度检测及金相分析,对铍青铜（QBe2）弹簧触指成形过程中的焊接及热处理关键技术进行了研究。试验证明,热处理前的弹簧触指焊接接头硬度偏低（平均值为133.6HV）,抗拉强度平均值为534MPa。在真空条件下,Y态＋时效处理条件下的母材与焊接接头的硬度比固溶＋时效状态下的稍高些;时效时间延长至90min时,焊接接头与母材的硬度均达到400HV以上,焊接接头抗拉强度平均值为820MPa,接近QBe2原材料Y态的抗拉强度（872MPa）,从而满足了弹簧触指的使用要求。     

铝合金与不锈钢热补偿电阻点焊接头性能研究

采用热补偿工艺垫片电阻点焊法对铝合金A5052与不锈钢SUS304异种材料进行了焊接。探讨了焊接参数对接头的抗剪与抗拉性能的影响,并通过电子显微镜对接合界面区进行了观察,分析了界面反应物形貌及厚度分布等微观特性。研究结果显示：一锯齿状反应层在接合界面生成,其厚度随焊接电流以及界面上位置的变化而变化,界面反应层对接头抗剪强度无影响,但能减弱接头抗拉强度。     

钨铜材料与铜的摩擦焊连接研究

用摩擦焊实现了W80Cu20和紫铜之间的连接，与与传统的整体烧结工艺进行了对比分析，观察了结合界面和拉伸断口。结果表明，摩擦焊焊接接头的抗拉强度与整体烧结的相当，接近或等于铜端的强度，结合界面组织均匀，晶粒细小，热影响区也轻窄，是一种制造钨铜材料复合件既经济又高效的工艺方法。     

Effect of process parameters on tensile strength of friction stir welding A356/C355 aluminium alloys joint

In the present investigation, A356/C355 aluminium alloys are welded by friction stir welding by controlling various welding parameters. A356 and C355 aluminium alloys materials have a set of mechanical and physical properties that are ideally suited for application in aerospace and automobile industries and not widely used because of its poor weldebility. To overcome this barrier, weldebility analysis of A356 and C355 aluminium alloys with high speed steel (Wc-Co) tool has been investgated. An attempt has been made to investigate the influence of the rotational speed of the tools, the axial force and welding speed on tensile strength of A356/C355 aluminium alloys joint. The experiments were conducted on a milling machine. The main focus of investigation is to determine good tensile strength. Response surface methodology (box Behnken design) is chosen to design the optimum welding parameters leading to maximum tensile strength. The result shows that axial force increases, tensile strength decreases. Whereas tool rotational speed and welding speed increase, tensile strength increases. Optimum values of axial force (3 /KN), tool rotational speed (900 RPM) and welding speed (75 mm/min.) during welding of A356/C355 aluminium alloys joint to maximize the tensile strength (Predicted 223.2 MPa) have been find out.