Explosive Welding Research Articles

Fatigue Analysis of Welded Joints Using a Thin-Walled Al/Fe Explosive Welded Transition Joints.

The study presents an analysis of S355J2+N steel and AA5083 aluminum alloy welded structural joints using explosion welded transition joints of reduced thickness. The transition joint thickness reduction significantly hinders the welding of the joints due to the risk of damage to the Al/steel interface as a result of the high temperatures during welding. In the previous article, the strength of the transition joint was analyzed but ship structures, apart from static loads, are subjected to many different cyclical loads. Welded structural joints are analyzed to determine the welding influence on the fatigue life and fracture type of the transition joints. The results of the fatigue tests show that the fatigue damage in the specimens occurs in the aluminum welded joint, and not in the explosively welded joint. The damage obtained was characteristic of cruciform welded joint specimens and both types of root and toe damage occurred. Based on the obtained results, fatigue curves for the joint were determined and compared to the fatigue curves for the AA5083 base material. The experimental fatigue curve was also compared with the design curve for welded aluminum structures from Eurocode. The conducted analysis showed the possibility of using Al/steel explosion welded transition joints of reduced thickness to transfer cyclical loads.

Explosive Welding and Friction Stir Welding/Processing of Multi-Principal Element Alloys

Explosive Welding and Friction Stir Welding/Processing of Multi-Principal Element Alloys

Formation characteristics and properties of an explosion-welded steel–aluminum composite with a diffusion barrier

ABSTRACT This paper presents a study of the formation characteristics and properties of an explosion-welded steel – aluminum composite with a chromium layer diffusion barrier. The identified characteristics of joint formation allowed us to determine the weldability range of the steel – aluminum composite with a diffusion barrier and define the optimal ranges of the explosion welding parameters. The chromium layer thickness, impact velocity, and plastic deformation energy significantly affect the magnitude and characteristics of plastic deformation during explosion welding of the steel – aluminum composite with a diffusion barrier. Thus, the steel – aluminum composite with a diffusion barrier has a higher strength and better quality than the aluminum – steel bimetal.

Microstructure and Mechanical Properties Investigations of Pure Titanium-Aluminum Alloy Composite Fabricated by Explosive Welding

Microstructure and Mechanical Properties Investigations of Pure Titanium-Aluminum Alloy Composite Fabricated by Explosive Welding

Laser shock dynamic compaction of aluminum–copper (Al–Cu) composite metal powder

Laser impact dynamic compaction experiments and 2D multi-particle finite element method (MPFEM) simulations were carried out on aluminum–copper (Al–Cu) binary-based composite powders. Al–Cu compacts with densities of about 95% were successfully prepared at the maximum laser energy of 1.8 J. Research trends indicate that higher power lasers could nearly achieve the theoretical densities. Analysis of the influence laws of laser energy and copper powder mass fraction on the densities of Al–Cu compacts was carried out, and the effects of microstructure and microhardness of Al–Cu compacts on their mechanical properties were investigated, as well as the stresses and velocities in the dynamic compaction process of Al–Cu composite powders were analyzed. The results showed that the relative densities of composite powder compacts of Al-5 wt%Cu gradually exceeded those of Al-10 wt%Cu and Al-15 wt%Cu with the increase of laser energy. In laser impact dynamic compaction the mechanism of inter-particle joining was solid-state press-welding, and the increase in the hardness of the Al–Cu compacts could be attributed to the inherent hardness of the hard particles. The upper particles have a localized maximum velocity of more than 300 m/s, which met the explosion welding velocity, thus localized cold welding occurred and contributed to the inter-particle connection.

Microstructure Evolution and Growth of Interfacial Intermetallic Compounds in NiCr/Ti Alloy Laminated Composite after Explosive Welding and Heat Treatment

The paper considers the issues of interaction of the molten metal at the interface of explosively welded NiCr/titanium alloy laminated composites with the reaction zone formed during heat treatment, as well as the features of its destruction after welding. It was established that the molten metal is a heterogeneous mixture based on Ni(Cr,Ti) and Ti(Ni,Al) solid solutions and NiTi and Ni3Ti intermetallic compounds. The estimated existence time of molten metal areas in the liquid state was ~10−8–10−11 s. The obtained values are comparable with the time of the unloading wave arrival at the contact surface, which is the reason for the presence of fracture areas in the form of detachments on the fracture surface. Continuous nanometer-size interlayers with an amorphous structure, due to the ultra-high cooling rate of the liquid melt, induce viscous destruction of the interface. Heat treatment at temperatures of 700 and 850 °C led to the formation of a layered reaction zone at the NiCr/Ti boundary, consisting of interlayers of solid solutions based on Ti2Ni, TiNi, and TiNi3 intermetallic compounds, as well as inclusions of a Cr(Ti) solid solution. The diffusion flow gradient was predominantly directed into the titanium alloy.

Solid-State Welding of Aluminum to Magnesium Alloys: A Review

With the continuous improvement of lightweight requirements, the preparation of Mg/Al composite structures by welding is in urgent demand and has broad prospective applications in the industrial field. However, it is easy to form a large number of brittle intermetallic compounds when welding Mg/Al dissimilar alloys, and it is difficult to obtain high-quality welded joints. The solid-state welding method has the characteristics of low energy input and high efficiency, which can inhibit the formation of brittle intermetallic compounds and help to solve the problem of the poor strength of welded joints using Mg/Al dissimilar alloys in engineering applications. Based on the literature of ultrasonic welding, friction welding, diffusion welding, explosive welding, magnetic pulse welding, and resistance spot welding of Al/Mg in recent years, this paper summarized and prospected the research status of solid-state welding using Mg/Al dissimilar alloys from three aspects: the optimization of welding parameters, the addition of interlayers, and hybrid welding process.

Numerical and experimental studies of the interface characteristics and wave formation mechanism of Hastelloy/stainless steel explosive welding composite plate

In this paper, Hastelloy UNS N10276 was joined to stainless steel UNS S30403 by explosive welding. Theoretical analysis, computer simulation, and experiment results are combined to study the interface characteristics and wave formation mechanism of the Hastelloy/stainless steel explosive welding composite plate. The macro morphology and microstructure of the composite plate’s interface were studied based on experimental research. And the explosive welding process was numerically simulated by ANSYS/AUTODYN. The formation mechanism of the wave interface was studied, and the physical quantities of the interface were analyzed, such as the temperature, the pressure, the heating rate, and the cooling rate. It was shown that the formation of microstructure in the melting zone was related to the temperature change history of the interface. The generation of the jet was the key factor to achieving explosive welding, and the formation mechanism of the wave interface was close to the indentation theory. Additionally, some significant phenomena in explosive welding have been studied.

Interfacial evolution mechanism of W/Cu explosive welding interface affected by preheating

Tungsten/copper (W/Cu) laminated composites possess high application potential in electronic, aerospace, and nuclear industries by combining the advantages of W and Cu. Among various fabrication methods, the explosive welding method is regarded as one rapid and cost-effective approach to producing W/Cu laminated composites considering the huge differences in physical properties between W and Cu. However, the lack of investigation on the bonding interface evolution between thick W plate and Cu plate inhibits the potential application of explosive welding on the large-scale production of the W/Cu laminated composites. In this study, the crack-free thick W/Cu laminated composites have been obtained successfully through the hot explosive welding approach, and the evolution mechanism of wavy interface formation is studied through numerical simulation and experimental investigation. The microstructure of welded W/Cu interface zone is further characterized to analyze the evolution mechanism of the wavy interface and corresponding bonding features. Moreover, the results of the mechanical property tests, such as compression shear, direct tensile, and micro-hardness tests, demonstrate that the welded W/Cu laminated composite features outstanding mechanical properties. Our study reveals the formation mechanism of the W/Cu interface during the hot explosive welding process and provides a rapid and efficient strategy to produce large-size W/Cu laminated composite with a thick W layer.

Microstructure and mechanical property of bonding zones between Ta foil and steel plate fabricated by explosive welding

This work aims to produce a thorough comprehension concerning microstructure related properties of the joint interface between Ta foil and steel plate fabricated by explosive welding. For this, a self-developed explosive welding configuration was employed to join Ta foil and steel plate, and different microscopic methods were adopted to investigate its microstructures and mechanical properties. It was found that the Ta/Fe interface was featured by regular wavy structures with a well-defined amplitude and period. The melted zones were mainly observed within the vortex structures, and occasionally at the Ta/Fe interfaces, which were formed by intense mixing of participating metals. The EBSD analyses revealed a diversity of the grain structures near the Ta/Fe interface, such as formation of the curved and elongated grains in Ta matrix, and fine equiaxed and columnar grains in Fe matrix. Especially, several adiabatic shear bands (ASBs) characterized by small equiaxed grains were found in Fe matrix, which were due to stress wave concentration in the narrow paths, and the materials in these zones underwent a recrystallization process. Finally, the nanoindentation results revealed inhomogenous mechanical behaviors in the bonding zones, which could be well related to the changes of microstructure and chemical composition.

Study of explosive welding of Al 5052 and Al 1100 with stainless steel wire mesh interlayer

Explosive welding is a solid-state welding process that uses a controlled explosive detonation to force two metals together at high pressure. The process has been fully developed for large-scale applications in the manufacturing industry. The explosive bonding technique can bond various similar and dissimilar materials and be applied to fabricate composites such as multi-layered and wire-reinforced materials. In this study, aluminium (Al-5052) and aluminium (Al-1100) plates were explosively welded with and without a stainless steel wire mesh interlayer. The microstructural studies illustrated the interface morphology of the interlayered wire mesh weld, which shows the formation of thin melted layers. However, wire mesh interlayered weld interfaces exhibit no molten layer formation. The maximum microhardness was observed at the interface due to wire mesh and plastic deformation.

Investigation of interfacial microstructure and mechanical characteristics of Ti/SS316 clads fabricated by explosive welding process

Investigation of interfacial microstructure and mechanical characteristics of Ti/SS316 clads fabricated by explosive welding process

Proposing an analytical model for predicting the dimensions of interfacial waves produced in the explosive welding of coaxial cylinders

There is an increasing interest in designing the explosive welding process and predicting its results. However, publications concerning explosive bonding have majorly focused on the welding of planar geometries. In this research, a novel analytical equation is presented for predicting the size of interfacial waves formed in the oblique collision of explosively-driven cylindrical surfaces. The experimental data from explosive welding of stainless-steel 316L to carbon steel CK22 tubes are used to validate the proposed model. In addition, the weldability window for this pair of metals is plotted. To calculate the impact angles, a series of numerical simulations are performed, considering three-dimensional (3-D) conditions. In these simulations, to reproduce the tubes’ impact and the detonation process, the Finite Element (FE) and Smoothed-Particle Hydrodynamics (SPH) methods are utilized, respectively. The findings of this research showed that the predictions of the proposed equation are consistent with the experimental data. However, by initiating the wavy-smooth transition, the corresponding values deviate from each other. Furthermore, examining the effects of the explosive load ratio on the collision velocity, it is observed that by reducing the load ratio from 0.552 to 0.14, the collision velocity decreased, linearly, by 77%. On the other hand, it is shown that the placement of design points within the allowable boundaries of the weldability window is the necessary condition for welding. However, to ensure the formation of a wavy interface, the kinetic energy lost per unit area should exceed a critical value. Compared with the conventional models, this critical kinetic energy can more accurately predict the initiation of the wavy-smooth transition process, for it considers the effects of varying thickness of the flyer tube. The value of the critical kinetic energy for the investigated pair of steel tubes, in this research, equals 515 J/cm2.

Analysis and Characterization of Three Charge Thicknesses in TA1/Al1060/Al7075 Explosive Welding Composite Process

The titanium/aluminum composite materials overcome the limitations of single metal materials and achieve lightweight, high-strength, and corrosion-resistant properties. However, there have been no reports on explosion-welded composites of titanium alloys and seven-series aluminum alloys. Therefore, TA1/Al1060/Al7075 explosion-welded plates with three different explosive thicknesses were successfully prepared using Al1060 as the transition layer. The SPH-FEM coupled algorithm was employed to analyze the detonation process in detail and predict the interface under different explosive thicknesses. The results showed that during the explosion welding process, the high temperature, pressure, and high-speed impact resulted in significant plastic deformation and jetting phenomena at the bonding interface, which were in good agreement with the experimental observations. With the increase in explosive thickness, the TA1/Al1060 bonding interface exhibited a flat shape, while the Al1060/Al7075 interface transitioned from a flat to a wavy morphology. Moreover, the crack, vortex, and TiAl3 were observed at the interface. Mechanical testing results revealed that the composite plate with a 35 mm explosive thickness exhibited the best tensile, shear, and bending performance, indicating the optimal process parameter. This study provides significant support and reference for the application of explosion welding technology in titanium alloys and seven-series aluminum alloy composite materials.

Evolution mechanism of fracture interface wave and microstructure during resistance butt spot welding

In this work, the interface wave was first shown in resistance butt spot welding of titanium (Ti) alloy and stainless steel (SS) as in explosive welding and magnetic pulse welding. Interface wave exhibited a fracture mode in the joint, so which were called fracture interface waves. The wavelength and the peak of the fracture interface wave weaken from the center of the joint to the outer edge. The formation of the wave is closely related to the interface microstructure. Fracture interface wave would have a direct impact on the joint properties. Analysis of the formation of fracture interface wave is helpful to improve the quality of the joint. Thermo-electric-mechanical-magnetic-flow coupling in resistance butt spot welding makes it difficult to explain the forming mechanism completely by existing theory and experiment methods. The key conditions of fracture interface wave propagation were analyzed by means of thermo-electric-mechanical numerical simulation. The formation process was explained in addition to the microstructure, mechanical properties.

Experimental and numerical investigation of interface and mechanical properties of Al0.3CoCrFeNi/304L explosively weld composite plate

High entropy alloys (HEAs) have gained attention for their excellent properties, but research on combining them with conventional metals is limited. This study manufactured Al0.3CoCrFeNi/304L composite plates using explosive welding. Welding parameters were determined based on the theoretical weldability window. The detonation process and interface were analyzed using an advanced SPH-FEM algorithm. Interface morphology was characterized using OM, EDS, and EBSD, and mechanical properties were tested. Materials near the interface experienced extreme conditions, resulting in severe plastic deformation and wave interface generation. Interface inhomogeneity wase caused by unsteady detonation and inclined collision. Collision velocity predicted by the SPH-FEM model matched theoretical calculations, and the predicted interface agreed with experimental results. Increased explosive charge led to more intense interface undulation and a thicker diffusion layer. EBSD showed a single-phase structure with non-uniform elements at the nanometer scale. The interface exhibited the highest deformation and grain recrystallization, along with plastic deformation and texture. Mechanical tests revealed that larger wave interfaces had higher hardness, improved tension, bending, and impact toughness, but worse shear performance. Explosive welding proved effective for achieving high-quality bonding between HEAs and conventional metals, offering promising possibilities for HEA and traditional metal composites.

Microstructural evolution and interfacial properties of explosively welded Nb/steel composite plate during post-heat treatment

In this work, Nb/steel composite plates were fabricated by explosive welding technique. Then post-heat treatments were conducted for large temperature range of 723 K–1273 K. Microstructural evolution and interfacial properties in welded interface were revealed by SEM, EBSD, XRD, microhardness, nanohardness and shear strength examinations. The effects of annealed temperature on interfacial microstructures and properties of Nb/steel composites were systematically investigated. The results demonstrated that microstructures and microhardness of Nb-side almost presented no changes with annealed temperature; Carbon elements from steel-side diffused easily into Nb-side forming a thin Nb carbide layer in which content of NbC increased as increasing annealing temperature; At 1273 K, formation of Nb2C was also found in carbide layers. In the steel-side, during low temperature (723 K–923 K) annealing, the deformed pearlite near interface recrystallized to form ferrite of which grains grew up with increasing annealed temperature; During high temperature (1073 K–1273 K) annealing, a large number of voids appeared at 1073 K, and typical normalizing structure generated at 1173 K–1273 K. Meanwhile, it was also found that with increasing of annealed temperature, shear strength firstly increased to maximum value of 326 MPa at 923 K and then decreased to 267 MPa at 1273 K. Failure mechanism of shear tests exhibited mixed ductile-brittle fracture at low temperature annealing; Then it converted into brittle fracture at high temperature annealing. Microhardness near interface of steel side firstly decreased to the minimum value of 106HV at 923 K and then increased to value of 220HV at 1273 K.

A New Strategy for Preparing Advanced Aluminum/Steel Joint Using Low‐Temperature Explosive Welding Technology

Obtaining a high‐quality Al/Fe joint remains a challenging task, due to formation of the various defects associated with melting phenomenon. Herein, a new strategy, lowering of initial temperature of the welded plates, is proposed to suppress the undesirable melting zone. Contrast experiments are conducted at low temperature (−50 °C) and room temperature (25 °C), respectively, and the microstructures and mechanical properties of the achieved joints are carefully investigated. It is found that this strategy is an effective way to improve the quality of Al/Fe joint, where the melting‐related defects are significantly reduced, and the bonding strength is increased by 18% when compared to the traditional method. In addition, the lowering of initial temperature enables to preserve the original properties of the parent metals by mitigating the impact‐induced grain structure evolution. This phenomenon is first demonstrated in this work and can be employed as a processing strategy to develop an advanced Al/Fe joint.

Effects of annealing on the interfacial microstructure and mechanical properties of explosively welded AZ80 magnesium alloy and A6005C aluminium alloy

Effects of annealing on the interfacial microstructure, mechanical properties, and residual stress of the explosively welded AZ80 magnesium alloy and A6005C aluminium alloy cladding plate were investigated. By explosive welding, a thin interlayer composed by an intermetallic compound, i.e. γ-Mg17Al12 phase, was formed at the interface of the cladding plate. After annealing at both 373 K and 473 K, the thickness of the interlayer increased. After annealing at 473 K, the interlayer changed from a single layer of γ-Mg17Al12 phase to a double layer of γ-Mg17Al12 phase and β-Al3Mg2 phase, resulting in a decrease in shear strength. As a result of nanoindentation measurement at the interface, the hardness was remarkably high in the β-Al3Mg2 phase. It was suggested that this phase became the crack initiation site for brittle fracture and the shear strength is decreased. Measurements of the residual stress using synchrotron radiation X-rays at the interface of cladding plate revealed the tendency of the generation of tensile residual stress on AZ80 magnesium alloy side and compressive residual stress on A6005C aluminium alloy side. After annealing at 473 K, residual stress in AZ80 magnesium alloy side and A6005C aluminium alloy side changed to compressive and tensile stresses, respectively, and these stress values became smaller in both cases. On the other hand, after annealing at 373 K, compressive residual stress was observed in both AZ80 magnesium alloy side and A6005C aluminium alloy side.

Interfacial investigations on the microstructure evolution and thermomechanical behavior of explosive welded CLAM/316L composite

In this paper, a comprehensive study combined multiple characterizations and SPH numerical simulation was conducted to investigate the microstructure evolution, extreme thermomechanical behavior and consequences of the explosive welded CLAM/316L interface. The interfaces of the two welding materials underwent remarkable temperature rise and rapid cooling under high-speed collision conditions, forming a tight bond that presents a wavy structure with vortices. The SPH simulation adequately reproduced the heating and cooling process of the interface during explosive welding, revealing the high heterogeneity of the thermodynamic behavior during the impact process. Furthermore, the EBSD analyses showed the perplexing evolution of crystal structure at the bonding interface with vortex, including ultra-fine grains, columnar grains, equiaxed grains, deformed grains and serious lattice distortion. By correlating the temperature histories and grain characteristics at different positions of the interface, the formation mechanism of diverse grains was revealed, referring to crystallization from liquid, recrystallization from the solid and plastic deformation. The recrystallization at the interface was closely related to the material properties, and the significant variations in dislocation density and plastic strain values at the interface, as well as the thermal softening of the material, could be explained by different degrees of dynamic recovery and recrystallization.