Investigation of explosive welding parameters and their effects on microhardness and shear strength

The aim of this study was to investigate the strength of explosive welded metals with the same chemical compositions. Different welding interfaces (straight, wavy and continuous solidified-melted) were used with changing explosive welding parameters [stand-off distance (s), explosive loading (R) and anvils]. Joined metals were investigated under heat-treated and untreated conditions. Results on the microstructure, microhardness, tensile shear strength and bending tests are reported. According to the experimental results, the effect of the anvil on the explosive welding process was only the joining or not-joining performance. It was shown that the bonding interface changed from a straight to a wavy structure when the explosive loading and stand-off distance were increased. For wavy interfaces, when the explosive loading was increased the wavy length and amplitude increased. Results of tensile shear and bending tests showed that heat-treated specimens have more strength than untreated samples. According to tensile shear test results, straight and wavy interfaces had similar strength. In addition, in bending tests of untreated specimens it was shown that the bending zone had some cracks.     

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.     

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.     

爆炸焊接理论与技术新进展

爆炸焊接理论与技术取得了四个方面的进展:(1)发现并重新定义了三种结合界面:大波状、小波状和微波状,其中以微波状为最佳.首次发现在一个复合板中,界面波呈一定的规律分布.(2)针对爆炸焊接熔焊机理的局限性,首次提出并验证了"爆炸焊接是一种特殊压力焊"的新观点.(3)为了得到无熔化的良好界面,必须选取焊接下限,按照新的复板模型,得到了新的焊接下限,比传统下限小20%,并适宜于工程应用.(4)首次测试并研究了爆炸焊接荷载下地基的应力应变规律.通过地基参数的优化分析,得到了最适宜于爆炸焊接的沙土地基(含水量17.00%、密度1.74g/cm3).     

Laser shock welding of aluminum/aluminum and aluminum/copper plates

This work describes an advanced technique for metal welding and composite production, namely laser shock welding. A series of laser shock welding experiments were conducted to verify the welding ability of aluminum/aluminum and aluminum/copper plates. Two kinds of interface morphologies were observed by metallographic investigation on cross-sections of the joint areas, including the linear and wavy interfaces. Besides, micro-hardness testing results show the welded interface has a much greater hardness than the base metals. The lap shearing test was used to characterize the joint. According to the experimental results, it can be imply that this kind of technique shares the same bonding mechanism with explosive welding and magnetic welding.     

钛/钢多层爆炸焊接界面的实验研究

为探究膨化硝铵炸药作用下,厚度均为2 mm的钛(Ti)、钢板的最优爆炸焊接参数以及验证一种新的爆炸焊接试验方案,实验采取阶梯型多层基板的爆炸焊接试验方案,以控制药量和间距为变量,并将Ti板作为复板,同时对多层阶梯型钢基板进行爆炸焊接试验;利用金相显微镜对焊接复合板进行观察,并分析多层基板同时焊接的方案可行性以及不同实验参数对界面波形的影响。试验结果和分析表明:通过观察Ti/钢复合板界面波形呈正弦微波状且无明显过渡层,验证了新方案的可行性,同时突出了阶梯型多层基板的同时爆炸焊接方案,能够在单次试验下对比分析不同基复板间距情况下的焊接效果的能力;并经分析得出在单位面积装药为1.048 g/cm~2及装药间距范围为(9~11)mm时,能得到质量较佳的Ti/钢爆炸复合板。     

紫铜-碳钢磁脉冲焊接接头界面形貌研究

为探索紫铜-碳钢磁脉冲焊接(MPW)接头界面形貌等微观特征,本文进行了T2紫铜管和50#钢管的磁脉冲焊接试验,在电压11 k V、径向间隙2.2 mm、重叠面积比3/4的条件下,获得了T2铜管-50#钢管冶金连接接头.通过光学金相、SEM/EDS、显微硬度和纳米压痕试验,重点研究了接头界面形貌、基体元素扩散和硬度分布.结果表明:接头由未焊合区、波状界面结合区、平直界面结合区等特征区域构成,连接区长度达到5 mm;波状结合区界面波长约为60μm,波峰幅值高约20μm;平直界面结合区基体元素扩散区(过渡区)宽度约2μm,而在波状界面结合区,扩散区宽度可达6μm;接头铜侧硬度相对初始值提高50%,最高硬度值出现在靠近界面的50号钢侧,而界面硬度介于两种母材之间.     

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。     

炸药量对爆炸焊接界面波影响的数值模拟

为了保证金属复合材料的爆炸焊接质量,对爆炸焊接过程中的爆轰荷载大小起着决定性作用的炸药量及布药方式进行了探索。应用AUTODYN非线性显式动力学分析软件,模拟了基、复板爆炸焊接复合过程,得到了不同炸药量下爆炸焊接过程中的压力时程,结合理论公式,分析炸药量、爆轰荷载、碰撞速度和界面波状之间的关系,及炸药量对爆炸焊接界面波的影响。并在复板上、下表面等间距各设置了8个关键点,比较了炸药厚度均匀布药方式和厚度递减布药方式产生的波状形态。结果表明,在可焊性窗口内,炸药量多的会产生较大波状结合界面;厚度递减布药方式能够消除均匀布药方式下界面波的不均匀现象,其中方案2的速度波动效果最好。并且已经结合的界面受到后续压力的振动破坏明显降低。     

Microstructure and mechanical properties of diffusion bonded Al/Mg2Si metal matrix in situ composite

In this research, Al/Mg₂Si composite produced by gravity casting, was joined by diffusion welding technique at 6 MPa pressure with various welding temperatures and durations. This metal matrix composite (MMC) containing 15% Mg₂Si particles was produced by in situ technique. Specific diffusion bonding process was introduced as a low vacuum technique. Microstructure and shear strength of the joined areas were determined. Scanning electron microscopy examination was carried out on the welded interfaces and shear tests were conducted to the samples interface to find out the effect of welding temperatures and durations on the weldability. It was found that high welding temperatures resulted in increase of shear strength. However, increase in welding duration did not make any detectable changes. The bonded interface could be developed as a wavy state depending on the amount of parent material deformation that was associated with bonding temperature. Results indicated that MMC can be joined by diffusion welding technique successfully with satisfactory shear strength.     

Research on explosive welding of aluminum alloy to steel with dovetail grooves

In order to explore a new method for the explosive welding of aluminum alloy to steel, a 5083 aluminum alloy plate and a Q345 steel plate with dovetail grooves were respectively employed as the flyer and base plates. The parameters adopted in the explosive welding experiment were close to the lower limit of weldable window of 5083 aluminum alloy to Q345 steel. The bonding properties of 5083/Q345 clad plate were studied through mechanical performance tests and microstructure observations. The results showed that the aluminum alloy and steel plates were welded under the actions of metallurgical bonding and meshing of dovetail grooves. The tensile shear strength of 5083/Q345 clad plate met the requirements of the bonding strength of Al/Fe clad plate. The interfaces between aluminum alloy and the upper and lower surfaces of dovetail grooves were mainly welded through direct bonding, and discontinuous molten zone emerged in the local region; while the interface between aluminum alloy and the inclined surface of dovetail grooves was bonded by continuous molten layer. The brittle intermetallic compounds FeAl₂ and Al₅Fe₂ were generated at the bonding interfaces of 5083/Q345 clad plate. The fracture surface of the tensile specimen exhibited ductile and quasi-cleavage fractures.     

厚板爆炸焊接窗口理论的应用

厚板爆炸焊接的焊接质量，焊接与否都比薄板更加强烈地依赖于爆速，复板加速间抛掷角，打击速度等焊接参数，该文根据可焊窗口理论，对厚板爆炸焊接参数选择时应注意的总理２进行了分析，尤其对焊接上限问题进行了较深入地讨论。     

1Cr18Ni9Ti-20G爆炸焊接+轧制工艺研究

为了研究在不同爆炸焊接工艺条件下获得的复合板的轧制效果,本文对大波、小波、微波状3种界面的1Cr18Ni9Ti／20G复合板进行轧制实验研究．实验表明：只有用下限获得的微小波状界面的爆炸焊接复合板,才能实现成功轧制,而大波状复合板界面存在一定的缝隙、空洞等微观缺陷,在轧制时由于分层会使轧制失效．爆炸焊接 轧制工艺获得的复合板结合界面的组织、强度和性能的测试结果表明：轧制复合板结合界面的剪切和分离强度虽比爆炸态略低,但延伸率、冲击韧性都大大增强,轧制复合板的耐蚀性能也未降低．     

SA266-304爆炸复合板的三种结合界面

运用JXA－8800M超大型电子探针对SA266—304爆炸复合板的结合界面进行了全面的分析测试，发现结合界面有大波状、小波状、微波状三类结合形式，其中以微波状为最佳．     

5083铝合金与CCSB钢的爆炸焊接研究

对直接爆炸焊接困难的5083铝合金与CCSB钢组合,采用加入中间层板CCSB一次爆炸焊接的可行性进行了试验探讨,确定了界面处的微观结构和爆炸焊接的参数范围。试验表明,爆炸时较大的能量作用在5083-CCSB钢界面区产生气化和熔化反应层是导致直接爆炸焊接困难的原因。通过在二者之间加入CCSB薄板的方法,能有效地减少作用在5083-CCSB界面上的能量,从而实现良好的结合。     

覆铜电气制品的爆炸焊接

作者开发了几种覆铜金属材料的电气制品，如电气行业中广泛使用的铜铝过渡板，建筑电气行业中普遍使用的闸刀开关，熔断器，插座，插头等，本文介绍其生产工艺和产品性能。     

Influence of post-weld heat treatment on microstructure and adhesion of Ti/Cu composite

It is well known that brittle interfacial intermetallics are typically present in laminated composites and degrade their mechanical performance. To investigate the relationship between intermetallics and mechanical properties, Ti/Cu-laminated composite plates prepared by explosive welding were studied with different heat treatments. A transition layer containing four zones of intermetallic phases, Cu₄Ti, Cu₄Ti₃, CuTi, and CuTi₂, was found at the interface between Ti and Cu after explosive welding. The intermetallics became thicker as the temperature of the heat treatment increased, especially for the CuTi phase. The sample treated at 473?K exhibited the highest bonding strength of 199.7?MPa, which was attributed to the elimination of residual stress during the welding and the diffusion of copper to improve interfacial bonding.     

Explosive welding of stainless steel–carbon steel coaxial pipes

Bi-metallic corrosion resistant steel pipes were produced through explosive welding process. The weldability window of the stainless steel pipe (inner pipe) and the carbon steel pipe (outer pipe) was determined by the use of available semi-empirical relations. The impact velocity of the pipes as the most important collision parameter was calculated by the finite element simulation. Direct effect of the explosive mass reduction on the bonding interface of the pipes was studied. Optical microscopy study showed that a transition from a wavy interface to a smooth one occurs with decrease in explosive load.     

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.     

Characterization of explosively bonded iron and copper plates

Explosive bonding between iron and copper plates was achieved under various conditions. A variety of experimental techniques were applied in order to investigate the bonding interface, including metallography, scanning electron microscopy, X-ray micro-analysis and X-ray diffraction. It was found that the bonding characteristics depend on the ratio of the explosive weight to the flyer plate weight (R ratio) and on the distance (X) from the detonation point. The microstructure of the molten pockets obtained depends strongly on their composition and on the cooling rate. Increasing the copper content in the molten pocket and the cooling rate resulted in a finer structure. Microstructural similarities between electron-beam molten surfaces and molten pockets in explosively bonded plates indicate, that cooling rates as high as 10⁵ K sec^–1 are obtained in both cases.