Explosive scarf welding of aluminum to copper plates and their interface properties

Explosive welding was used to produce scarf joint between aluminum and copper plates. This process is known as explosive scarf welding (ESW). In a scarf joint, the final bond interface is oblique. In this study, chamfered end of aluminum and copper plates were joined explosively and named scarf joint, employing changes in chamfered angle at different stand‐off distance and explosive loading. The geometry of scarf joint enables consideration of both flyer and base plate thickness and explosive loading and the effects on mechanical properties of interface such as bond shear strength and micro‐hardness can be investigated. Mathematical models developed on the interface properties of scarf joint to make relationship between the bond shear strength and explosive loading ratio. To check the adequacy of developed models, mechanical properties of interface, such as bond shear strength was predicted and compared with actual values in explosive cladding process. The results show reasonable agreement with theoretical predictions. Consequently, mathematical model which is based on scarf joints, can predict bond shear strength of cladding metals under desired explosive loading and flyer plate thickness.     

防护层对爆炸焊接质量的影响

为了研究防护层在炸药爆轰过程中对复板表面的保护作用,依据实验数据,分析了复板在焊接完成后的表面平整度、是否发生熔融现象以及金属结合界面的波状纹理的变化情况。防护层隔绝高温的炸药爆轰产物对复板侵蚀,同时在爆轰初始阶段对于应力波透过防护层作用在复板上的应力有明显的增强效应。最终确定在爆炸焊接过程中对复板厚度为0.2cm时,在其表面均匀覆盖一层0.05⁰.15cm的黄油可以较好地保护复板不受高温的爆轰产物侵蚀。实验过程中,选取不同种类炸药进行了对比实验,发现粉状硝铵炸药更加容易装药和控制爆轰速度,本实验选用硝铵炸药完成。     

Examination of copper/stainless steel joints formed by explosive welding

In this study, bonding ability of copper and steel with explosion welding was investigated using different ratios of explosive and different stand-off distance. Experimental studies showed out that, copper and stainless steel could be bonded with a good quality of bonding properties with explosion welding. In the bonding interface, intermetallics were not formed. It was observed that, when explosive ratio and stand-off distance were increased smooth bonding interface was transformed to a wavy bonding interface. As the ratio of explosive and stand-off distance increase, the amplitude and wavelength of wave were increased. It was found that, hardness of bonding interface and outer face of plates were increased because of deformation that was originating from impact the effect. Total interface area increased as a result of wavy interface, which was caused by increased explosive ratio and stand-off distance. In addition, wavy interfaces did not separate after tensile-shearing test. Bending tests applied on bonded samples had different diameters indicated that interfaces of the bonded samples have not any defect. EDS analyses in SEM showed that diffusion did not take place between bonding plates, however, diffusion was observed after annealing of the bonded samples for different times.     

防护层对爆炸焊接质量的影响

为了研究防护层在炸药爆轰过程中对复板表面的保护作用,依据实验数据,分析了复板在焊接完成后的表面平整度、是否发生熔融现象以及金属结合界面的波状纹理的变化情况。防护层隔绝高温的炸药爆轰产物对复板侵蚀,同时在爆轰初始阶段对于应力波透过防护层作用在复板上的应力有明显的增强效应。最终确定在爆炸焊接过程中对复板厚度为0.2cm时,在其表面均匀覆盖一层0.05~0.15cm的黄油可以较好地保护复板不受高温的爆轰产物侵蚀。实验过程中,选取不同种类炸药进行了对比实验,发现粉状硝铵炸药更加容易装药和控制爆轰速度,本实验选用硝铵炸药完成。     

SUS304不锈钢/Q345R碳钢爆炸焊接工艺参数研究

针对实际生产中在爆炸焊接窗口内取值时因为所取参数不同而导致生产的复合板结合强度差异较大这一现状,通过对SUS304不锈钢／Q345R碳钢爆炸焊接窗口内不同工艺条件得到的复合板进行剪切强度测试及金相分析,得到界面结合强度与界面波形的关系以及两者随工艺参数的变化规律,找到窗口内最佳的工艺参数,以提高爆炸焊接复合板质量以及生产效益。研究表明：界面波形的波长和振幅随着装药量的增加而增大,随基复板间距的增加先增大后减小。爆炸焊接窗口内最佳工艺参数取值范围与复板厚度有关。复板为薄板（3mm）时,取得最佳结合强度时界面波形波长为1250μm左右,振幅为200μm左右,对应的最佳装药质量比为1．02,基复板间距为8mm,取值比理论最佳值偏高;复板为厚板（6mm）时,取得最佳结合强度时界面波形波长为900岫,左右,振幅为100μm左右,对应的最佳装药质量比为0．45,基复板间距为14mm,取值靠近下限。当界面波长与振幅相同时,复板为薄板的结合强度要高于厚板。     

双层爆炸复合中覆板最小可焊厚度的分析

为了研究双层爆炸焊接中覆板的最小可焊厚度,分析了爆炸焊接对于炸药布药量的要求,提出了一种利用爆炸焊接的碰撞速度下限与覆板的一维平板运动公式计算爆炸焊接中覆板最小可焊厚度的方法,并采用爆炸焊接中常用的3种炸药,分别对不锈钢-钢、铝-钢、钛-钢、铜-钢的爆炸焊接最小可焊厚度进行计算,计算得出4种覆板的最小可焊厚度分别在1.5、2.5、2.0、1.5 mm左右。同时指出在进行小厚度覆板的爆炸焊接时,由于密度更低的炸药爆轰压力也更低,可以更好地适用于小厚度覆板的爆炸焊接。     

T2纯铜/2024铝合金爆炸焊接接头界面结构及性能

为研究铜铝异种金属爆炸焊接头界面形成机理,采用爆炸焊对T2纯铜和2024铝合金进行了焊接.通过光学显微镜、扫描电镜、X射线衍射、万能材料试验机和纳米压痕仪,对T2/2024复合板结合界面的显微组织、成分分布和力学性能进行了测试分析.结果表明:T2/2024合金爆炸复合板结合界面呈波状结合,结合界面主要由平直界面、波状界面和局部熔化层界面构成;靠近结合界面处,基体金属发生塑性变形,晶粒细化;反应层主要成分为AlCu和Al_2Cu的混合物.复合板拉剪试验表明,T2/2024合金爆炸复合板平均结合强度为67 MPa,纳米压痕测试反应层平均硬度可达8 GPa.     

Flyer plate motion and its deformation during flight

Velocity and peripheral deformation of a flyer plate, driven by the detonation of contact explosive, have been studied during its flight both theoretically and experimentally. In theoretical formulations, density or velocity of the detonation products behind the flyer plate have been assumed to vary linearly; the results thus obtained compare well with the experimental results. Several experiments were performed in which the guard ring size and air gap between the explosive and the plate were varied. The arrangement which gave negligible peripheral deformation is presented.     

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.     

Non-linear transient dynamic response of rectangular plates under shock loading

Experimental and numerical investigations were carried out on clamped rectangular plates subjected to underwater explosion loading. Experiments were conducted on rectangular plates of size 0.55×0.45×0.004 m using a box model set-up under air-backed conditions in a water tank detonating small charge weights of PEK-I explosive. Corresponding plastic deformation of the plates were measured for different charge weights and stand off distances. Numerical analysis was carried out using the MARC finite element code for various test conditions and the results are compared with experimental results.     

近距离爆破引起的隧道周边振动场

首先分析了近距离爆破造成的隧道周边振动场分布规律 ,指出最大振动速度出现在爆破振动波正入射部位的墙壁和拱部 ,墙脚点振动速度较小 ,背爆侧振速只有迎爆侧的 1 / 2 5。其次 ,根据大量测试数据分析 ,论述了爆破性质、地质条件对振动衰减的影响 ,并作了进一步的理论解释。最后根据振动分析 ,提出了有关降低爆破振动的措施     

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．     

减小爆炸焊接边界效应影响研究

边界效应是爆炸焊接普遍存在的问题,如何消除边界效应是提高爆炸焊接复合质量的关键。本文提出了减小边界不焊区的两种方法:①等面积爆炸复合时,采取加大布药宽度和在焊接窗口内适当加大质量比R的办法,将稀疏波作用范围引出复合面积之外,减少炸药边界稀疏波对飞板飞行速度的影响;②不等面积爆炸复合时,采取把飞板边界刨去一部分或开应力槽的方法,减少复合板周边打伤打裂现象。通过大量爆炸焊接试验的检验结果来看,复合板周边的焊合情况非常令人满意。与工程经验的方法相比,不但装药量可节省10%左右,降低生产成本,而且还可降低基、复板之间的碰撞速度,对减小复合板的整体变形和对解决爆炸焊接中的开裂问题十分有利,从很大程度上优化了焊接工艺。     

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.     

Assessment of bond interface in impact spot welding

Results of an investigation on weld interfaces of impact-welded dissimilar metal combinations are presented. Polymeric projectiles of various nose shapes are utilized at an average impact speed of 750 m/s. It is found that welded interfaces generally comprise wavy and plane zones. Areas adjacent to waves contain hardened and plastically deformed regions. Quantitative data is presented on the composition of copper/brass interfaces. Results of microhardness measurements on copper/brass, titanium/brass and zirconium/brass weld interfaces are provided. Measurements on the local plastic thinning of the flyer plate (FP) are furnished. Effects of standoff distance (SD) and FP thickness on interface characteristics are investigated.     

Explosive welding of aluminum to aluminum: analysis, computations and experiments

6061 T0 aluminum alloy was joined to 6061 T0 aluminum alloy by explosive welding. This is a process in which the controlled energy of a detonating explosive is used to create a metallic bond between two similar or dissimilar materials. The welding conditions were tailored to produce both wavy and straight interfaces.

A three-pronged study was used to establish the conditions for straight weld formation: (a) analytical calculation of the domain of weldability, in which the Szecket–Mayseless (Mater. Sci. Eng. 57 (1983) 149) criterion was successfully used; (b) characterization of the explosive welding experiments carried out under different conditions, and (c) 2D finite differences simulation of these tests using the explicit Eulerian hydrocode Raven with a Johnson–Cook constitutive equation for the Al alloy. The numerical simulation and the analytical calculations confirm the experimental results and explain the difficulties met for obtaining a continuous straight interface along the entire weld.     

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).     

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.     

Experimental and numerical study of isotropic circular plates' response to underwater explosive loading,created by conic shock tube

Today, to reduce the cost and increase the safety, test devices like conic shock tube have been widely used to investigate the underwater explosion phenomenon and its impact on structures. A shock tube is designed, manufactured and utilized in the mechanic of explosion laboratory of mechanic faculty of K.N. Toosi University of Technology to study the effect of isotropic metal plates' material in the present study. The source which creates shock in the utilized shock tube is an explosive material and the positive point is that in such a tube a high pressure is produced with a tiny explosive charge. In order to investigate the effect of the material and the geometry of the utilized metal plate, three materials are considered with two different thicknesses in the experimental tests. The behavior of the plate can be measured if the amount of the pressure produced by the explosive charge and the amount of plate's transformation is specified. To present a semi‐experimental equation of the behavior of the plate which is under the explosion loading with the water interface in the experimental tests, numerical simulation is performed with LS‐Dyna software. At the end, by combining the experimental and simulation results, the effect of the material and the thickness changes is studied specifically and an explosive charge is provided by adding weight parameter to anticipate the transformation of these metal plates.     

Analysis of stationary deformation behavior of a semi-infinite rigid-perfect plastic beam subjected to moving distributed loads of finite width

The problem of projection of a flyer plate with a traveling distributed load and subsequent collision of it to a base plate, as applied to explosive welding, is addressed in this paper. A semi-infinite solid-perfectly plastic beam is employed to model the flyer plate subject to two transverse pressure profiles, traveling at constant speed on its top and bottom surfaces, which represent the explosion and collision loads, respectively. A steady state deformation process is considered and the analysis is developed for the pure bending and combined shear and bending deformation conditions. It follows from analysis that two plastic bending hinges form ahead and at the rear end of each pressure profile and travel at constant velocity. Furthermore, when the width of the pressure is small, the shearing deformation region is generated within the loaded area. The state of the deformation in the collision stage in contrast to the propulsion stage is discussed.