铜/不锈钢加筋板爆炸焊接工艺实验

随着我国核电新能源的发展,新型材料的需求也在不断的增加,铜/不锈钢加筋板是其中一种,具有重要工程应用价值,目前无法用常规的冷、热加工工艺进行生产。通过爆炸焊接法,采用一种新的"凸台式"装药形式,在支撑模板设计及其填充方案、工装等方面进行了深入研究,优化了焊接参数,并对成品的结合界面进行了剪切强度测试、金相观测、电镜扫描和显微硬度测试。检测结果表明:铜/不锈钢焊接结合面为波状冶金结合界面,在波峰两侧存在含金属氧化物的"冠状"漩涡,结合界面附近的晶粒被拉长变细,显微硬度显著升高,界面结合强度超过铜材。     

铜/不锈钢加筋板爆炸焊接工艺实验

随着我国核电新能源的发展,新型材料的需求也在不断的增加,铜/不锈钢加筋板是其中一种,具有重要工程应用价值,目前无法用常规的冷、热加工工艺进行生产。通过爆炸焊接法,采用一种新的"凸台式"装药形式,在支撑模板设计及其填充方案、工装等方面进行了深入研究,优化了焊接参数,并对成品的结合界面进行了剪切强度测试、金相观测、电镜扫描和显微硬度测试。检测结果表明:铜/不锈钢焊接结合面为波状冶金结合界面,在波峰两侧存在含金属氧化物的"冠状"漩涡,结合界面附近的晶粒被拉长变细,显微硬度显著升高,界面结合强度超过铜材。     

Effect of explosive characteristics on the explosive welding of stainless steel to carbon steel in cylindrical configuration

The aim of this research is to study the influence of explosive characteristics on the weld interfaces of stainless steel AISI 304L to low alloy steel 51CrV4 in a cylindrical configuration. The effect of ammonium nitrate-based emulsion, sensitized with different quantities and types of sensitizing agents (hollow glass microballoons or expanded polystyrene spheres) and Ammonium Nitrate Fuel Oil (ANFO) explosives on the interface characteristics is analyzed. Research showed that the type of explosive and the type and proportion of explosive sensitizers affect the main welding parameters, particularly collision point velocity. The morphology of the wavy weld interfaces, chiefly the amplitude and length of the waves, is affected both by the impact velocity and the type and particle size of the explosive sensitizers, and increases with particle size. All the weld interfaces, except welds done with ANFO, displayed localized melted and solidified regions, whose chemical composition resulted from the contribution of both flyer and base metal.     

Effect of heat treatment on bonding interface in explosive welded copper/stainless steel

In this investigation, explosive welding and heat treatment processes provided an effective method for manufacturing high-strength and high-ductility copper/ austenitic stainless steel couple. In order to improve diffusion in the interface of copper/stainless steel, first the tensile samples were provided from the welded part, then they were subjected to annealing at 300 °C (below recrystallization temperature) for 8–32 h with 8 h intervals and then samples were cooled in the furnace. Optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were utilized to evaluate the possibility of diffusion in the joints. Moreover, in order to measure the hardness of the samples, microhardness test was performed. Microstructural evaluations showed that the stainless steel 304L had a wavy interface. Furthermore, the post heat treatment process resulted in great enhancement of diffusion. Microhardness measurements showed that the hardness of the sample near to the interface is greatly higher than other parts; this is due to plastic deformation and work hardening of copper and stainless steel 304L in these regions. The interface of samples with and without the post heat treatment was exhibited ductile and brittle fracture, respectively.     

The influence of some factors on steel/steel bonding quality on there characteristics of explosive welding joints

Explosive welding is a solid state process in which controlled explosive detonations force two or more metals together at high pressures. The resultant arrangement is joined with a high quality metallurgical bond. The aim of this study was to investigate of strength of explosive welding metals which had same chemical compositions. In this study, it was taken different welding interfaces (straight, wavy and continuous solidified-melted) with changing explosive welding parameters (stand-off distance (s), explosive loading (R) and anvils). Joined metals were investigated in heat treatment and non heat treatment conditions. Microstructures, microhardness, tensile shear strength and bending test results were reported. Effect of anvil on explosive welding process was evaluated in joining/no joining performance. It was shown that bonding interface changed from straight to wavy structure when explosive loading and stand-off distance were increased. On wavy interface, when explosive loading was increased wavy length and amplitude increased. Results of tensile shear and bending tests showed that heat treated specimens have more strength than which of unheat-treated ones. According to tensile shear test results, straight and wavy interfaces had similar strength. Also, bending zone has shown some cracks after the bending test of unheated specimens.     

不锈钢/钢复合管水压爆炸焊接制造的数值模拟

为研究水压爆炸焊接法制造不锈钢/钢复合管的焊接效果及炸药与复合管之间水层厚度对焊接的影响,对传统内爆法制备双金属复合管的工艺安装进行了优化,并利用有限元软件ANSYS/LS-DYNA建立了不锈钢/钢复合管水压爆炸焊接制造的二维有限元模型,对其焊接过程及变形情况进行了数值模拟研究.在模拟过程中得到复管与基管碰撞结合面节点的速度曲线和结合界面的压力曲线.结果表明:炸药与复管之间水层厚为1.5 cm时,模拟焊接过程中得到复管的最大飞行速度约453 m/s,基复管结合界面的压力约9.46 GPa,均满足爆炸焊接窗口理论计算值的下限要求,可以实现焊接;复管的最大飞行速度随水层厚度增加而减小,复管与基管有效焊接时间随水层厚度增加而增加;炸药与复管之间增加水层能有效地防止基、复管的大变形.水压爆炸焊接法为薄厚度、变形差等特殊材质双金属管的制造提供了一个重要的借鉴与参考.     

Testing of explosive welding and welded joints: joint mechanism and properties of explosive welded joints

In this study physical mechanism of explosive welding joint was analysed. The mechanism refers to wavy joint with interpass and without one. Plastic strain, viscosity and acoustic waves were applied to explain the problem. The own model of the mechanism of oxide removal for the direct joint and test results confirming the bonding mechanism were showed.     

Weldability and properties of martensitic/austenitic stainless steel joints

Abstract

A series of studies has been carried out to examine the weldability and properties of dissimilar steel joints using martensitic and austenitic stainless steels F6NM (OCr13Ni4Mo) and AISI 347, respectively. This type of joint requires good mechanical properties, corrosion resistance, and a stable magnetic permeability in addition to a good weldability. Weldability tests include weld thermal simulation of the martensitic steel to investigate the influence of weld thermal cycles and post-weld heat treatment (PWHT) on the microstructure and mechanical properties of the heat affected zone (HAZ); implant testing to examine the tendency for cold cracking of martensitic steel; and rigid restraint testing to determine hot crack susceptibility of the multipass dissimilar steel joints. The simulation results indicated that the toughness of the martensitic steel HAZ did not change significantly after the weld thermal cycles. The implant test results indicated that welds produced using nickel based filler show no tendency for cold cracking, whereas welds produced using martensitic or ferritic filler show such a tendency. Based on the weldability tests, a welding procedure (tungsten inert gas welding for root passes with HNiCrMo-2B wire followed by manual metal arc welding using ENiCrFe-3B coated electrode) was developed and a PWHT at 600°C for 2 h was recommended. Joints produced using the developed welding procedure are not susceptible to hot and cold cracking. After PWHT the joints exhibit both satisfactory mechanical properties and stress corrosion cracking resistance.

MST/1955     

钛/钢双立式爆炸焊接参数优化

为解决大面积钛/钢爆炸焊接窗口窄,在结合区易出现"过熔"和"射流堆积"等微观缺陷的问题,开展了双立爆炸+轧制综合制造技术,进行了低爆速爆炸焊接用炸药试验优化,发明了一种最低临界爆速爆炸焊接用炸药,设计确定了刚性防护板和柔性防护墙构成的双立综合防护结构及参数,研究了钛/钢爆炸焊接装药厚度窗口.结果表明,双立钛/钢复合板结合界面成波状结合,几乎不存在金属熔化、漩涡等微观缺陷.     

Testing of explosive welding and welded joints. The microstructure of explosive welded joints and their mechanical properties

The present essential models and some theories were applied to explain the wavy phenomenon, microstructure and mechanical properties of the characteristic joint area. Two phenomena occurring in the plate collision zone during welding were carefully tested. These phenomena were connected with forming the wavy joint surface and the interpass. The available data referring to forming the interpass were further developed.     

Production of stainless steel wire-reinforced aluminium composite sheet by explosive compaction

Composite sheet material has been produced by explosively compacting stacks of alternately placed stainless steel wire meshes and aluminium foils. It was found that stacks could be satisfactorily bonded by using an aluminium driver plate which was prevented from bonding to the stack by interposing a polythene sheet. Stacks containing six or seven layers of mesh and having a wire volume fraction of up to 0.24 could be bonded when the driver plate kinetic energy exceeded 120 J cm^–2. It is concluded that the bonding mechanism involves cold pressure welding of the matrix metal by extrusion through the mesh apertures, and the aperture size is a controlling factor in bonding. No evidence was found of strong bonding between the wires and the matrix. In the production of larger sizes of composite sheet, (300 mm×500 mm), blistering and tearing occurred due to the presence of excess air in the stack, a consequence of bowing of the foils by the springy and curved pieces of mesh. This difficulty was overcome by enclosing the stack in a polythene envelope, which was evacuated before detonation of the charge, so that the stack was compressed by atmospheric pressure. Tests have shown that tensile and fatigue properties of the composites compare favourably with other aluminium matrix composites and with high strength aluminium alloys.     

Effect of welding processes on fatigue crack growth behaviour of AISI 409M ferritic stainless steel joints fabricated using duplex stainless steel fillers

The present investigation aims to study the effect of welding processes such as shielded metal arc welding (SMAW), gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW) on fatigue crack growth behaviour of the ferritic stainless steel (FSS) conforming to AISI 409M grade. Rolled plates of 4 mm thickness were used as the base material and AISI 2209 grade duplex stainless steel (DSS) was used as filler metal, for preparing single pass butt welded joints. Centre cracked tensile (CCT) specimens were used to evaluate the fatigue crack growth behaviour. From this investigation, it is found that the GTAW joints showed superior fatigue crack growth resistance compared with SMAW and GMAW joints. The reasons for the superior performance were discussed in detail.     

Formation of stainless steel layer on mild steel by welding arc cladding

The discrete microstructural characterization and the formation of stainless steel layer on mild steel where produced in cladding deposits, and fusion boundary region were investigated using tungsten inert gas (TIG) arc, high current pulsed arc and constricted plasma arc. The experimental procedure involved making bead-on-plate method for controlled travel speed, employing filler metal by using tungsten inert gas arc, pulsed current gas tungsten arc and transferred plasma arc, with subsequent sectioning and examination of the reaction interface. For TIG arc cladding, using filler metal of small diameter the deposit does not become stainless steel, but on using 3.2 mm diameter filler metal it becomes stainless steel with less than 50% dilution. For pulsed arc cladding, the complete stainless steel is not obtained on account of the existence of an incomplete mixture, particularly at the fusion boundary region. However, on using a large diameter filler metal at a pulse frequency of 500 Hz, the complete stainless steel microstructure has been accomplished. The plasma arc cladding can be achieved in such a way that the conversion into stainless steel on the mild steel surface — which is the microstructures of cellular austenite in cladding deposit and cellular dendritic austenite containing δ or σ-phase in fusion boundary region — is possible irrespective of the melt penetration and the dilution. The following conditions were found to be beneficial for the formation of stainless steel microstructure layer on the mild steel: using large diameter filler metal, below 50% dilution, and further rendering arc localized and constricted.     

Construction and characterization of stainless steel/polyurea/E-glass composite joints

This work was motivated by the desire to improve the long-term durability of E-glass/Hysol 9394 epoxy/Al-6XN stainless steel joints whose fracture energy in a previous study was shown to fall from ∼950 J/m² (ambient) to a mere ∼88 J/m² after only two days of exposure to a 90%RH, 50 °C environment. This paper reports a new polyurea chemistry to bond the E-glass and steel sections with very promising results. The fracture energy under ambient condition was measured to be 1232 ± 15 J/m² using a double cantilever beam experiment. This value degraded by only 13% to 1070 ± 35 J/m² in samples that were conditioned for 30 days at 90%RH and 50 °C. The failure in all samples was cohesive, within the first ply of the E-glass composite that neighbored the polyurea interface. The intrinsic fracture energy measurements, devoid of inelastic effects, were also carried out by submerging samples in a liquid nitrogen bath. Values of 590 ± 25 J/m² were obtained, which can be used by the designers to set the local failure condition in design simulations of large-scale structures.     

Fatigue damage of stainless steel diffusion-bonded joints

Vacuum diffusion bonding was carried out on 316L stainless steel. Metallographic inspections and micro-hardness testing were conducted near the interface of diffusion-bonded joints. Fatigue tests were performed to investigate the mechanical performance of diffusion-bonded joints under cyclic loading. Results indicate that, although the static strength of joints closes to that of base metal, fatigue life of the diffusion-bonded joint is markedly lower than that of the base metal. Increments of electrical resistance of specimens were monitored and recorded at different cycles. By taking the electrical resistance as a damage parameter, the evolution of fatigue damage of diffusion-bonded joints was interpreted and the relationship between fatigue life and increments of electrical resistance was established. Overall good agreement between the experimental results and predicted life was obtained which provides confidence in the use of the developed approach for life prediction.     

铜/钢爆炸焊接头界面组织及力学性能研究

为了揭示铜/钢爆炸焊接的结合机理,采用光学显微镜(OM)、扫描电子显微镜(SEM)和纳米压痕仪等对T2纯铜/Q245钢爆炸焊接头结合界面组织和微力学性能进行了分析.结果表明:T2纯铜/Q245钢爆炸复合板结合界面呈现较规则的正弦波形,界面结合良好,界面处原子发生强烈扩散,形成了过饱和铜钢固溶体;界面不同区域固溶体微力学性能不同,纳米硬度在2.02~3.08 GPa,弹性模量在129.6~172.1 GPa;由界面弹性模量分布云图可知,固溶体层连续分布在界面上,由于界面原子扩散程度不同,部分区域的固溶体层厚度很薄,在光镜下很难识别,而在波峰处固溶体则比较明显.固溶体的弹性模量均比铜基体的大,其原子键合强度强于铜基体原子,在一定程度上增强了界面的结合强度,从而使界面的结合强度高于铜基体;爆炸焊接头的拉剪试验断裂位置均位于铜侧,也证实了界面结合强度高于铜基体的强度。     

焊接参数对铁素体不锈钢搅拌摩擦焊接头组织及性能的影响

对4mm厚T4003铁素体不锈钢进行搅拌摩擦焊接工艺实验,研究焊接参数对接头组织特征、硬度分布及常温和低温冲击韧性的影响。结果表明:接头搅拌区和热力影响区由铁素体和马氏体双相组织构成;接头搅拌区组织沿试样厚度方向存在非均质性,且随转速的降低及焊接速率的增加越发显著;转速从150r/min增加至250r/min,前进侧热力影响区组织呈现小梯度过渡趋势,无明显变形拉长特征。焊缝硬度分布相对均匀,其最高硬度为290HV,约为母材的1.87倍。焊接参数和温度对接头的冲击吸收功有较大影响:常温(20℃)下,热影响区为母材的90%～92%,搅拌区为母材的85%～103%;低温(-20℃)下,热影响区为母材的87%～97%,搅拌区为母材的82%～95%,表明焊缝区仍具有较好强韧匹配。     

双电极奥氏体不锈钢焊条单弧焊工艺研究

本文研究了双电极奥氏体不锈钢焊条单弧焊电弧的静特性、焊接电流、电弧电压、焊芯间隙对双电极焊条单弧焊的工艺性能和焊缝成形的影响;通过热电偶测试技术,对双电极焊条单弧焊焊接过程中不同部位焊芯表面温升进行了测定.研究结果表明焊芯直径为φ4.0mm的双电极A102焊条,其合适焊接工艺参数为:焊接电流140～160A,电弧电压45V左右,焊条两芯间隙1.2～1.5mm,焊接板厚8mm的1Cr18Ni9Ti材料,焊缝成形良好.     

Microstructural features of dissimilar MMC/AISI 304 stainless steel friction joints

The microstructure and mechanical properties of dissimilar friction joints between aluminium-based MMC and AISI 304 stainless steel base materials were investigated. The microstructural features which occur in the stainless steel substrate comprise deformation twinning, formation of a fine-grained dislocation substructure in austenite, and plastic deformation. The stainless steel substrate was plastically deformed in the region close to the mid-radius of the dissimilar joint. In a similar manner, 5–10 m thick transition layers, comprising regions of locally plasticized MMC-base material, were formed close to the mid-radius location in dissimilar joints. The interlayer formed at the dissimilar joint interface comprised a mixture of oxide (Fe(Al,Cr)₂O₄ or FeO(Al,Cr)₂O₃) and FeAl₃ intermetallic phases. The notch tensile strength of dissimilar MMC/AISI 304 stainless steel joints increased when the rotational speed increased from 500 r.p.m. to 1000 r.p.m., and at higher rotation speeds, there was no effect on notch tensile strength properties.