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.     

钛-钢板爆炸焊接的影响因素及炸药配方

爆炸复合用炸药是影响爆炸焊接效果的最主要因素,不同的材料和工艺参数对炸药的爆速、比冲量和能量有不同的影响,其中炸药的密度直接影响复板斜碰撞基板的速度和角度。选用低合金高强度结构钢Q345B和工业纯钛TA2为实验材料,通过理论计算与实验研究,得到了一种较为适合钛-钢板爆炸焊接用的炸药配方,并对钛-钢爆炸焊接影响因素进行了探讨。     

钛-钢板爆炸焊接的影响因素及炸药配方

爆炸复合用炸药是影响爆炸焊接效果的最主要因素,不同的材料和工艺参数对炸药的爆速、比冲量和能量有不同的影响,其中炸药的密度直接影响复板斜碰撞基板的速度和角度。选用低合金高强度结构钢Q345B和工业纯钛TA2为实验材料,通过理论计算与实验研究,得到了一种较为适合钛-钢板爆炸焊接用的炸药配方,并对钛-钢爆炸焊接影响因素进行了探讨。     

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.     

塑料超声波焊接过程及质量研究 III焊接接头质量影响因素分析

从焊接工艺参数对焊件熔化状态及焊件熔化状态对接头质量的影响两个方面对塑料超声波焊接质量影响因素进行了研究 ,揭示了焊件熔化状态是影响接头质量的直接因素 .利用光学显微镜研究了接头的组织形貌 ,发现接头熔合区组织具有明显的取向 .对接头剪切和弯曲强度进行测试 ,发现接头力学性能具有各向异性 ,熔和区厚度和组织取向程度对接头有重要的影响 .     

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。     

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。     

塑料超声波焊接过程及质量研究 Ⅱ焊接接头熔化膜厚度计算模型

利用流变学基本理论 ,对焊接过程平衡阶段熔化膜的流动形态进行了理论分析 ,分别导出了工艺参数对熔化膜厚度和熔体剪切速率影响的计算公式 ,测量结果表明 ,理论计算结果和实际结果一致性较好 .     

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.     

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.     

Numerical simulation of explosive welding using the material point method

Explosive welding involves detonation of explosive, interactions of fluid-structure and plastic deformations of metal plates at the instant of the explosion. Conventional mesh-based methods such as the finite element method (FEM) and finite difference method (FDM), are limited in simulation of the explosive welding when mesh distortion and interaction of different materials occur. In order to describe process of the explosive welding and accurately predict physical parameters for the explosive welding, numerical simulation of the explosive welding which involves multi-physical phenomenon is performed by using material point method (MPM). Not only can major physical phenomena of explosion impact be well captured, but also some important technical parameters for the explosive welding can be attained based on the MPM simulation. Through the comparison with the experimental results, it is shown that the MPM is a robust tool in simulation of the explosive welding.     

An investigation of mechanical and metallurgical properties of explosive welded aluminum-dual phase steel

The aim of this paper is investigation of microstructure and property relationship in aluminum-HSLA steel and aluminum-dual phase steel bimetals fabricated by explosive welding technique. Dual phase steel was produced by intercritical annealing and water quenching from 1.45Mn-0.2Si-0.186C HSLA steel. Hardness, tensile shear strength, tensile strength, toughness and microstructure of explosively welded aluminum-HSLA steel and aluminum-dual phase steel were evaluated. Both bimetals have a straight bonding interface. It was also seen that plastic deformation of dual phase steel was higher than HSLA steel near interfaces of bimetals. The hardness was increased near the bond interface of bimetals. Tensile and tensile shear strength tests showed that aluminum-dual phase steel is superior than aluminum-HSLA steel. Also, impact toughness of aluminum-dual phase steel was found significantly higher than that of aluminum-HSLA steel.     

塑料超声波焊接过程及质量研究 I焊接过程接头熔化状态分析

采用抗冲击型聚苯乙烯 (HIPS)标准试件 ,利用热电偶测温系统对焊件接触表面的温度变化进行了实时检测 ,并利用OFV— 5 0 2型激光干涉仪对焊件下塌量的变化过程进行了研究 .发现塑料超声波焊接过程具有导能筋熔化、熔化膜形态变化、熔化挤出平衡及保压四个明显的阶段 ,这对超声焊接质量的分析具有重要的指导意义 .     

Study on the microstructure and mechanical properties of explosive welded 2205/X65 bimetallic sheet

In this study, microstructural inhomogeneity and mechanical properties of explosive welded 2205 stainless steel/X65 pipe steel bimetallic sheets were investigated. The explosion-bonded 2205/X65 bimetallic sheets had good shear strength. The tensile shear fracture primarily occurred in the interior of X65 material and primarily exhibited dimple morphology. Fine crystal grains in the 0.5–2 μm range were found all over the narrow localized melted zone near the 2205/X65 interface, whereas a coarse columnar crystal structure growing along the perpendicular direction to the interface formed in the wider localized melted zone. Quasi-cleavage fracture morphology was observed in the coarse columnar crystal region after the stratified tensile test. The junction of the three regions near the interface with large differences in morphology was the weak point in the bimetallic sheet, where Y-shaped cracking easily occurred under a loading force. Stratified tensile test and micro-hardness tests for the explosively welded bimetallic sheet showed that severe hardening occurred in the 2205 cladding, and the most severe metal hardening occurred near the interface. Tests for 45° face bending and root bending tests were conducted under extreme conditions. The results showed that voids were prone to appeared in the peninsula and island morphologies near the interface.     

Hierarchical microstructure of explosive joints: Example of titanium to steel cladding

The microstructure of explosive cladding joints formed among parallel Ti and steel plates was examined by electron microscopy. The bonding interface and the bulk materials around it form pronounced hierarchical microstructures. This hierarchy is characterized by the following features: at the mesoscopic scale of the hierarchy a wavy course of the interface characterizes the interface zone. This microstructure level is formed by heavy plastic shear waves (wavelength ≈ 0.5 mm) which expand within the two metal plates during the explosion parallel to the bonding interface. At the micro-scale range, intermetallic inclusions (size ≈ 100-200 μm) are formed just behind the wave crests on the steel side as a result of partial melting. Electron diffraction revealed FeTi and metastable Fe_9.64Ti_0.36. Most of the observed phases do not appear in the equilibrium Fe-Ti phase diagram. These intermetallic inclusions are often accompanied by micro-cracks of similar dimension. At the smallest hierarchy level we observe a reaction layer of about 100-300 nm thickness consisting of nano-sized grains formed along the entire bonding interface. Within that complex hierarchical micro- and nanostructure, the mesoscopic regime, more precisely the type and brittleness of the intermetallic zones, seems to play the dominant role for the mechanical behavior of the entire compound.     

Ni—Ti形状记忆合金爆炸焊接与复合的试验研究

Ni-Ti形状记忆合金是一种新型的功能材料，采用传统的高温熔融焊接后，常常改变焊接热影响区的形状记忆功能，严重影响了这一功能材料的应用领域。对于冲击韧性值较低的形状记忆舍金，能否实现同种材料的爆炸焊接与异种材料的爆炸复合，并达到其冶金结合，是人们积极探索的一种新方法。采用下限法对形状记忆合金爆炸焊接与复合技术进行了试验研究，并通过增加缓冲板改变常规平行法布药结构，以降低复板运动速度，实现了Ni-Ti合金直接结合的最佳爆炸焊接界面和Ni-Ti合金与0Cr18Ni9及黄铜H62板复合界面的波状结合。     

Fatigue life assessment of improved joints welded with alternative welding techniques

In this study, the fatigue life improvement by adopting the toe weaving technique on non-load carrying cruciform welded joints has been investigated. Fatigue testing was conducted on two batches of specimens welded using double-pass manual welding. One batch had a straight second pass and the other was weaved. The influence of different weaving shape parameters was analyzed by performing crack growth analyses. The fatigue testing shows a slightly improved fatigue life for the two different batches compared to as-welded joints; the improvement is similar for both batches. The crack growth analysis concludes that the batch with the straight second pass should provide slightly higher fatigue life compared to the toe weaved batch. Measurements show a presence of undercuts in the vicinity of the crack initiation site. Nonetheless, an increased fatigue life is obtained, due to the low flank angle created during welding of the second pass, which reduces the stress concentration in the weld toe, prolonging the fatigue life.     

爆炸焊接用低爆速粉状乳化炸药研究

为降低岩石粉状乳化炸药的爆速,选择了一种HW矿物粉,通过筛混方式将该分散剂与炸药混合,并测定了该分散剂加入量和布药厚度对炸药爆速的影响。结果表明,岩石粉状乳化炸药中掺入44.5%⁵0%的HW矿物粉时,爆速为1913m/s50%的HW矿物粉时,爆速为1913m/s²378m/s,经钢与不锈钢板爆炸焊接试验表明,爆炸结合率达100%,可满足金属爆炸焊接用炸药的要求。     

爆炸焊接用低爆速粉状乳化炸药研究

为降低岩石粉状乳化炸药的爆速,选择了一种HW矿物粉,通过筛混方式将该分散剂与炸药混合,并测定了该分散剂加入量和布药厚度对炸药爆速的影响。结果表明,岩石粉状乳化炸药中掺入44.5%~50%的HW矿物粉时,爆速为1913m/s~2378m/s,经钢与不锈钢板爆炸焊接试验表明,爆炸结合率达100%,可满足金属爆炸焊接用炸药的要求。     

Fatigue strength of mash seam welded joints

Reversed bending fatigue tests have been conducted using four series of mash seam welded joints obtained from the coupling of two different steels and plate thicknesses. Fatigue strength was evaluated and the effects of material property changes resulting from welding were studied. Fatigue strength of all series of the welded joints decreased slightly compared with that of the base steel. Type of steel and plate thickness in the welded samples exerted very little influence on fatigue strength. In the welded joints between steels with the same plate thickness, fatigue failure took place at a location away from the weld zone in the plate with the lower strength, while in the welded joints between plates of different thickness, failure occurred at the shoulder between the thin and thick plate, i.e. at the weld zone. Regardless of the type of steel and the plate thicknesses joined, fatigue strengths of the mash seam welded joints were slightly higher than those of the laser welded butt joints.