A Study of the Structure of Steel – Titanium Joints Formed by Diffusion Welding with the Use of Ultrafine Nickel Powder

Metal Science and Heat Treatment - The structure and phase composition of welded joints of austenitic steel 08Kh17N10T and titanium alloy PT-3V formed by diffusion welding with an intermediate...     

Simulation of the elastic deformation of laser-welded joints of an austenitic corrosion-resistant steel and a titanium alloy with an intermediate copper insert

The macro- and microstructures and the distribution of elements and of the values of the microhardness and contact modulus of elasticity along the height and width of the weld metal and heat-affected zone of austenitic corrosion-resistant 12Kh18N10T steel (Russian analog of AISI 321) and titanium alloy VT1-0 (Grade 2) with an intermediate copper insert have been studied after laser welding under different conditions. The structural inhomogeneity of the joint obtained according to one of the regimes selected has been shown: the material of the welded joint represents a supersaturated solid solution of Fe, Ni, Cr, and Ti in the crystal lattice of copper with a uniformly distributed particles of intermetallic compounds Ti(Fe,Cr) and TiCu₃. At the boundaries with steel and with the titanium alloy, diffusion zones with thicknesses of 0.1–0.2 mm are formed that represent supersaturated solid solutions based on iron and titanium. The strength of such a joint was 474 MPa, which corresponds to the level of strength of the titanium alloy. A numerical simulation of the mechanical behavior of welded joints upon the elastic tension–compression has been performed taking into account their structural state, which makes it possible to determine the amplitude values of the deformations of the material of the weld.     

钛合金/纯铝异种金属摩擦焊接工艺

进行了TC4钛合金与L5纯铝异种金属的摩擦焊接工艺及其焊后回火热处理工艺研究,利用光学金相分析、扫描电镜EDX线扫描、拉伸性能及硬度的测试,探讨了TC4钛合金与L5纯铝异种焊接接头焊合区的微观组织及其力学性能.研究表明,T℃4钛合金与L5纯铝间具有良好的摩擦焊接性,焊合区无金属间化合物相生成,焊接接头强度等于或高于铝基材.经焊后回火热处理,摩擦焊接头两侧主要合金元素的扩散区宽度增大,焊合区钛合金侧的硬度值因时效作用而有所提高.     

Brazing zirconium alloys with an amorphous rapidly quenched strip brazing alloy

Application of aluminum alloy, which is a typical lightweight material, has been expected to achieve energy saving and prevention of pollution in many kinds of transportation vehicles. While the structure made of whole aluminum alloy, however, is lightweight, it still has problems, such as low mechanical strength and high cost. Hence, a hybrid or joining structure made of aluminum alloy and steel seems to be reasonable because of its light weight and higher strength.

To make a hybrid structure for transportation vehicles, we examined welding by friction stirring between aluminum alloy and low-carbon steel, which could be welded without melted weld materials. As a result, welding between aluminum alloy and low-carbon steel that had a thin intermetallic compound at the weld interface was obtained.

In recent automobile manufacturing, zinc-coated steel has been used for structural parts in general. On welding between zinc-coated steel and other materials such as aluminum alloy, existence of a Zn layer between aluminum and steel has to be taken into account to get a high-quality joint between the materials.

In this study, spot joining between aluminum alloy and several kinds of zinc-coated steels by friction stirring was carried out, and the effect of the coated layer both on the weld strength and weld interface microstructure was investigated. As a result, the joint between aluminum alloy and zinc-coated steel was stronger than that between aluminum alloy and non-coated steel, when the coated layer was removed at the weld interface by plastic flow of aluminum alloy.     

钛合金与不锈钢扩散焊接研究进展

分析了钛合金与不锈钢的物理化学性能的差异对焊接接头性能的影响,综述了国内外钛合金与不锈钢扩散焊接的研究现状,对钛合金与不锈钢的焊接界面进行表面自纳米化处理后,在扩散焊接过程中能够显著提高原子扩散系数,抑制脆性金属间化合物生长,改善接头组织和提高接头综合性能。展望了钛合金与不锈钢扩散焊接的发展趋势。     

热喷涂及热处理对45钢表面组织和性能的影响

采用金相显微镜、扫描电镜分析和显微硬度测试等手段,研究了喷焊及回火温度对镍基自熔合金粉末涂层组织和性能的影响。结果表明:在结合面上,元素互相扩散,形成亮白色带状的过渡层,基体母材区受热较少,组织变化不大。碳元素扩散进入喷焊层后,与Cr形成(Fe,Ni)23C6及Cr的碳化物,这些硬质相阻碍喷焊层晶粒的张大,致使晶粒细化,在45钢中形成粗棒状或块状组织。喷焊层与基体之间形成了良好的冶金结合,合金元素在喷焊层与基体界面附近连续分布,保证了较高的结合强度。     

Al/Ti的扩散焊工艺

根据Al合金与Ti合金在高温下具有一定的互溶性原理,采用Ti热浸Al工艺利用扩散焊接方法进行Al/Ti材料的焊接. 焊接后构件抗拉强度达到180 MPa,焊缝性能稳定,具有一定的实际应用价值.     

Effects of resistance spot welding parameters on microstructures and mechanical properties of dissimilar material joints of galvanised high strength steel and aluminium alloy

Abstract

Intermediate frequency resistance spot welding has been adopted to join dissimilar materials of H220YD galvanised high strength steel and 6008 aluminium alloy. The effects of welding current and welding time on microstructures and mechanical properties of the welded joints were investigated. A thin intermetallic compound layer composed of Fe₂Al₅ phase and Fe₄Al₁₃ phase formed at the steel/aluminium interface. The interfacial intermetallic compound layer has higher nanohardness compared with the aluminium alloy nugget and galvanised steel. With increasing welding current (4–11?kA) and welding time (50–300?ms), the nugget diameter increased, the interfacial layer structure became coarser and the tensile shear load of the welded joints had an increased tendency. The maximum tensile shear load reached 3309?N at 9?kA for 250?ms. Crack initiated at the interfacial intermetallic compound layer of the tensile shear specimens, then propagated through the interfacial layer principally, and meantime through the aluminium alloy fusion zone near the interface partially.     

电镀阻隔层对钛/钢电子束焊接接头性能的影响

采用电子束熔化焊、电子束阻隔焊和电子束阻隔熔-钎焊方法来实现钛合金与不锈钢异种金属之间的连接。研究发现钛合金与不锈钢连接界面处产生的脆性金属间化合物是影响接头性能的关键因素。采用电子束直接熔化焊和阻隔熔化焊钛合金和不锈钢时,接头界面会产生贯穿性裂纹导致焊缝直接断裂。电子束阻隔熔-钎焊中利用熔化的不锈钢润湿未熔化的钛合金母材,并采用Ag、Cu作为中间层添加元素,在结合界面处形成了很好的阻隔屏障,减少了Ti/Fe界面的金属间化合物的产生,减缓了应力,实现了钛合金与不锈钢的冶金结合,接头抗拉强度约为100 MPa。电子束阻隔熔-钎焊得到的钛合金/不锈钢异种金属焊接接头焊缝正反面成形良好,X射线探伤未发现裂纹和气孔缺陷。     

纯铝中间层厚度对铝/钢点焊接头性能的影响

采用纯铝作为中间层对铝合金与低碳钢进行了电阻点焊,分析中间夹层厚度对界面反应层厚度和接头抗拉强度的影响。在钢/中间夹层界面观察到有界面反应层生成,其主要由靠近钢侧的Fe2Al5和靠近中间夹层铝侧的FeAl3两种金属间化合物组成。与不加中间夹层相比,利用纯铝作为中间夹层点焊的铝合金与低碳钢的接头具有较薄的界面反应层和较高的接合强度。随着中间夹层厚度的增加,界面反应层厚度逐渐减小,而接头抗拉强度则呈增大趋势。结果表明,采用纯铝作为中间夹层点焊铝合金与钢具有一定的有效性。     

铝/钛异种金属激光/激光-CMT复合熔钎焊工艺及其组织与力学性能

选用5A06铝合金和Ti6Al4V钛合金为母材,ER4047焊丝和粉状Nocolok钎剂为填充材料,采用激光熔钎焊和激光-CMT复合熔钎焊两种焊接方法,并对两种焊接接头的微观组织和力学性能进行对比分析.结果表明,激光熔钎焊与激光-CMT复合熔钎焊在合适的焊接工艺下均容易获得连续、稳定的焊接接头.铝/钛激光熔钎焊和激光-CMT复合熔钎焊焊缝中部组织均为α-Al固溶体和Al-Si共晶组织.激光熔钎焊和激光-CMT复合熔钎焊均在钛合金上表面处界面反应层最厚,其厚度分别小于10和6μm.激光熔钎焊焊缝偏钛侧界面主要为锯齿状,激光-CMT复合熔钎焊焊缝偏钛侧界面主要为层片状.激光熔钎焊和激光-CMT复合熔钎焊焊接接头均断裂在焊缝区,焊接接头平均抗拉强度分别为252和209 MPa,激光熔钎焊比激光-CMT复合熔钎焊接头抗拉强度高20%,而激光-CMT复合熔钎焊比激光熔钎焊焊接效率提升约1.5倍.     

NiPdCrBSi合金的钎焊组织与性能研究

以真空雾化制粉技术制备了NiPdCrBSi合金粉末,采用差热分析(DTA)、扫描电镜(SEM)、金相显微镜(OM)和真空钎焊等技术,对所得合金粉末的形貌、熔化特性,以及在不锈钢上的焊接铺展组织进行研究,并对钎焊界面组织进行分析表征。结果表明,NiPdCrBSi合金钎料在不锈钢上的润湿铺展性良好,所形成的焊接界面层的润湿机理,主要以扩散机制为主导,增强了合金的焊接性能和可靠性。     

中国低活化马氏体钢TIG焊焊缝耐液态Pb-Bi腐蚀性能分析

文中研究了中国低活化马氏体（china low activation martensitic,CLAM）钢对接双层TIG焊焊缝在高速流液态Pb-Bi中的腐蚀行为.结果表明,腐蚀的主要特征是元素扩散迁移和表面形成双氧化层结构.焊后热处理改善了CLAM钢焊缝耐液态Pb-Bi腐蚀性能.研究发现试样经760℃保温0.5 h的回火热处理后,耐腐蚀性能最好.均匀细小的马氏体组织有效地提高了焊缝的耐蚀性能,马氏体组织的尺寸大小是焊缝耐蚀性能的决定性因素.试样焊缝区最先损坏,表现为内氧化层中出现裂纹导致氧化层脱落.因此,提高反应堆结构材料焊缝处的耐腐蚀性能可以有效延长结构材料的使用寿命.     

7A04铝合金/304不锈钢连续驱动摩擦焊及焊后热处理

对7A04铝合金与304不锈钢异种材料进行了摩擦焊接试验,并对接头进行了不同温度、不同时间的退火处理.对接头飞边形貌、抗拉强度、断口形貌、金相组织、显微硬度等进行对比分析.结果表明,采用合适的工艺参数能获得形貌良好的飞边和更好的抗拉强度,焊合区的铝合金组织发生动态再结晶,晶粒细化,组织比基材更加致密,结合面两边互有元素扩散,焊合区显微硬度高于基材.经400℃×3 h退火处理的接头其抗拉强度提升明显,界面形成了不同的金属间化合物,扩散层厚度略有增加,显微硬度值有所下降.     

Fe-Cr-2Al-Si阻尼合金与1Cr18Ni9Ti不锈钢的钨极氩弧焊接

采用钨极氩弧焊（GTAW）和奥氏体不锈钢焊丝LNT309LSi作为填充金属,研究了Fe-Cr-2Al-Si阻尼合金和1Cr18Ni9Ti不锈钢的焊接工艺和焊接质量。借助金相显微镜分析了焊缝组织特征,采用电子探析分析了焊缝成分。按照国家标准研究了焊接接头的硬度、拉伸性能和弯曲性能。结果表明,用奥低不锈钢焊丝焊接Fe-Cr-2Al-Si阻尼合金和1Cr18Ni9Ti不锈钢,可获得理想的奥氏体＋少量的铁素体＋马氏体的焊缝组织,焊缝的抗拉强度和抗弯性能均高于阻尼合金。所采用的焊接方法、焊接工艺和焊丝能满足这两种钢的焊接要求,焊接质量可靠。     

Ti/Cu异种金属电子束焊接界面行为

为了获得高强度T2铜和Ti-6Al-4V钛合金异种金属接头,采用电子束焊方法开展试验,并对接头界面组织及力学性能进行了分析.试验在钛/铜熔钎焊接基础上,通过在高熔点钛侧复合二次焊接,构建钛/铜结合界面金属间化合物层的重熔温度场,进而实现钛/铜金属间化合物层的重熔改性.通过有限元温度场模拟及SEM,XRD等检测.结果表明,钛侧重熔焊接可在结合界面处形成1 000℃左右高温,金属间化合物层发生局域重熔.在随后凝固过程中,由于散热方向及元素再分配,相的形成顺序发生改变,钛原子向铜侧的扩散距离减短,高硬度相TiCu向Ti2Cu转变,相结构优化,最终接头强度得以提升.     

电极板辅助点焊钢/铝异质接头的组织与性能

采用电极板辅助点焊进行了H220YD高强钢与6008-T66铝合金异种金属的连接,研究了接头的微观组织和力学性能.结果表明,焊接接头是通过液态铝合金在钢/铝界面处对高强钢的润湿铺展而形成的,本质上属于熔-钎焊接头.钢/铝界面上生成了由Fe2Al5和FeAl3组成的金属间化合物层.接头中铝合金熔核直径在焊接电流为14kA、焊接时间为300 ms时达最大值为9.5 mm.接头拉剪力随焊接电流的增加先迅速增大后趋于稳定,当焊接电流为12 kA、焊接时间为300 ms时达4.3 kN,比不加电极板时提高约30%.在接头拉剪过程中裂纹的扩展路径不仅沿着金属间化合物,还部分经过铝合金熔核内部.     

采用不同结构Cu/V填充层的钛合金/不锈钢电子束焊接试验

对采用不同结构Cu/V填充层的钛合金与不锈钢电子束焊接头横截面形貌、微观组织及力学性能进行了分析.结果表明,采用片层结构的Cu/V填充层进行焊接时,焊缝组织由钒基固溶体、铜基固溶体及铁基固溶体组成,但由于焊缝底部有钢层未熔,形成未熔合缺陷,接头强度为288 MPa.采用楔形结构的Cu/V填充层,在保持接头固溶体过渡组织结构特征的同时,消除了未熔合缺陷,接头抗拉强度达到385 MPa.未熔钒层为接头力学性能薄弱区域,不同结构填充层的焊接接头断裂均发生于未熔钒层处.     

Study of friction welding of polyethylene

The technologies of intermediate coating and diffusion welding of standard columnar laboratory specimens of the joint of the austenitic steel and titanium alloy are well-tested. Materials for the intermediate coating are chosen. Tensile tests on the welded joints are carried out at the temperature of 18–20°C. The technology of copper coating on steel and niobium coating on titanium is the most prospective.     

等离子表面渗Nb对γ-TiAl合金扩散焊接性能的影响

采用双辉等离子表面渗金属技术在名义成分为Ti-45Al-8.5Nb (W, B, Y) 的γ-TiAl合金表面制备了Nb涂层。使用SEM、EDS、XRD等手段研究了不同渗Nb温度、焊接温度对γ-TiAl合金扩散焊接接头微观组织及性能的影响。结果表明,在800～950 ℃的渗Nb温度范围内均可以在γ-TiAl合金表面形成致密的Nb涂层,随着渗Nb温度的升高,Nb涂层晶粒尺寸和表面粗糙度均不断增大。典型的接头组织从基体向焊缝中心可分为4层:I层(Nb涂层与基体间扩散层)、II层(含有少量AlNb₂的Ti-Nb互溶层)、III层(富Ti-TiNi层)、IV层(近等原子比TiNi层)。接头的剪切强度随渗Nb温度和焊接温度的升高均呈先增大后减小的趋势。渗Nb温度为850 ℃,焊接温度为900 ℃时获得的接头剪切强度最高,达到82.0 MPa。