Explosive Welding Technique Research Articles

Experimental and numerical study on ballistic impact behavior of explosively-welded double-layered Weldox700E targets against ogival-nosed projectiles

In this work, explosive welding technique was used to fabricate 2 mm + 2 mm thick double layered Weldox700E steel targets. The bonding interface exhibited wave-shaped patterns without obvious micro-defects, grain refinement and grain elongation were observed. With specially designed shear specimen and tensile specimen, Ultimate stresses of the bonding interface under shear and tensile loadings were measured to be 526 MPa and 683 MPa, respectively. Ballistic impact tests against ogival-nosed projectiles were conducted on both explosively welded double-layered targets and double-layered contact targets. Ballistic limit velocities of the two target configurations were respectively 225.32 m/s and 203.98 m/s , with the former being 10.5 % higher than the latter. For both target configurations, localized bulging and petal-shaped cracking were observed; specially, welded bonding interface remains well bonded even after perforation of the projectile. Combining experimental results and numerical simulations, it was found that the explosively welded double-layered targets exhibited better ballistic performance than double-layered contact ones. The good welded bonding interface provides a better overall deformation capability for the explosively welded double-layered target, which is an important reason for the improved ballistic performance of the target. Although hardness tests show that there is a significant hardened layer in the explosively welded double-layered target, and the hardness value can reach up to 409.4 HV. However, the thin hardened layer cannot significantly improve the ballistic performance of the explosively welded double-layered target in the high-speed impact process of the projectile.

Mechanism and growth kinetics of Al3Ti phase in fifteen-layered Ti Gr.1/A1050 clads produced with the explosive welding technique

This study was dedicated to the detailed characterization of the microstructural changes and the phase analysis of the interfaces formed in explosive welding of multilayered Ti Gr.1/A1050 clads. The significant effect of the detonation source localization on the microstructure of the welded materials interfaces after collision, and consequently on the diffusion processes induced by the elevated temperature was showed. Annealing process at 550 °C for series of time intervals of the Ti/Al clad allowed to determine the growth mechanism of the Al3Ti phase formed along particular interfaces. Moreover, the microstructure observations and calculations evidenced different growth mechanisms related to the localization of the Ti/Al interface in respect to the detonation source.

Microstructure and corrosion resistance of Ni-Ti-Al multi-layer laminates manufactured by explosive welding with subsequent rolling

In the present work, an explosive welding technique was used to manufacture novel multi-layer laminates consisting of nickel (Ni), titanium (Ti), and aluminium (Al). Produced laminates were subsequently plastically deformed using symmetrical and asymmetrical rolling. The aim of the study was to correlate the changes in the microstructure that occur during the applied processes with the corrosion resistance of the samples. Two planes were characterized – an outer Ni surface and a cross-section of the laminates. In the first case, the changes caused by the welding and rolling, i.e., reduction in grain size and increase in the fraction of low angle grain boundaries and geometrically necessary dislocations, were insufficient for influencing the corrosion resistance in two examined environments – 0.1 M sodium sulphate (Na2SO4) and 0.5 M sodium chloride (NaCl). When cross-sections of the samples were analyzed, electrochemical experiments in sodium chloride revealed distinct changes between the samples with higher susceptibility to localized corrosion of the laminate, as the presence of Ti and Ni accelerated the corrosion processes and active dissolution of the Al layer. After rolling, the corrosion current density was lowered. The examination of the surface after the tests revealed that corrosion attack occurred only in Al layers, where numerous pits were observed. After rolling, a smaller number of pits are present compared to the sample directly after explosive welding.

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.

Experimental and numerical investigation on interface microstructure and phase constitution of radiation resistant Pb/316L stainless steel explosive welded composite plate

As one of the shielding materials, lead (Pb) and its alloy exhibit excellent ray absorption and radiation shielding ability due to its high density and atomic mass. In this work, the explosive welding technique was successfully performed to join Pb/316L dissimilar metals. To revel the microstructure characteristics and phase constitution of the joining interface, the electron backscattered diffraction test and numerical simulation were carried out. It was concluded that the slight waveform structure without obvious defects or cracks was obtained at the explosive welded interface. The fine grains zone, sub-grains and twin structures were formed due to the severe plastic deformation. Meanwhile, the recrystallized structures, substructures and deformed structures were also confirmed at the joining interface during the high strain rate impact. In addition, five different deformation textures and recrystallization textures were confirmed due to severe plastic deformation and dynamic recrystallization. Furthermore, the numerical simulation results also showed a slight waveform structure at the Pb/316L explosive welded interface, which was consistent with the experimental results.

The interface microstructure and phase constitution of Nb/316L composite plates fabricated by explosive welding

ABSTRACT Niobium has a reputation for its superior superconducting, high strength and corrosion resistance at elevated temperatures. In this work, the explosive welding technique was successfully performed to join Nb/316L dissimilar metals. To reveal the phase constitution and texture distribution at the joining interface, the EBSD test was carried out. It was concluded that an irregular large wavy structure of fine crystal, sub-grains and twin structures was formed. In addition, the recrystallised structures, substructures, deformed structures and local internal stress at the joining interface were attributed to severe plastic deformation and rapid solidification of liquid metal. Furthermore, six different deformation textures and recrystallisation textures were confirmed at the joining interface due to severe plastic deformation and dynamic recrystallisation.

Microstructure-related properties of explosively welded multi-layer Ti/Al composites after rolling and annealing

The processes of rolling and annealing of explosively welded multi-layered plates significantly affect the functional properties of the composite. In current research, fifteen-layered composite plates were fabricated using a single-shot explosive welding technique. The composites were then rolled up to 72% to reduce layer thickness, followed by annealing at 625 °C for varying times up to 100 h. Microstructure evolution and chemical composition changes were investigated using scanning electron microscopy equipped with energy-dispersive spectroscopy. The mechanical properties of the composite were evaluated by tensile testing, while the strengths of individual layers near the interface were evaluated by micro-hardness measurements. After explosive welding, the wavy interfaces were always formed between the top layers of the composite and the wave parameters decreasing as the bottom layers approach. Due to the rolling process, the thickness of Ti and Al layers decreases, and the waviness of top interfaces disappeared. Simultaneously, the necking and fracture of some Ti layers were observed. During annealing, the thickness of layers with chemical composition corresponding to the Al3Ti phase increased with annealing time. A study of growth kinetic shows that growth is controlled by chemical reaction and diffusion. The results of micro-hardness tests showed that after annealing, a fourfold increase of hardness can be observed in the reaction layers in relation to the Ti, while in relation to Al, the increase of hardness is even 15 times greater.

Phase constitution and texture distribution in the vortex zone of Co/Cu explosive welded plates

Cobalt has a reputation for its excellent electrical and magnetic properties, and exceptional wear and corrosion resistance, which has many applications in the batteries, electronic industry and semiconductor industry. In this work, the explosive welding technique was successfully performed to join Co/Cu dissimilar metals. To reveal the phase constitution and texture distribution of the vortex zone at Co/Cu joining interface, the electron backscatter diffraction (EBSD) test was carried out. It was concluded that the typical vortex structure composed of fine crystal band, sub-grains and twin structures was formed at the Co/Cu joining interface. In addition, the dynamic recrystallized structure and local internal stress at the vortex was attributed to severe plastic deformation and rapid solidification of liquid metals resulted from high strain state collision. Furthermore, the S, copper, brass and fiber deformation textures and the cube and gross recrystallization textures were confirmed at the vortex zone due to plastic deformation and dynamic recrystallization.

Investigations on the microstructure evolution and mechanical properties of explosive welded ODS-Cu/316 L stainless steel composite

In this paper, the explosive welding technique was introduced to manufacture ODS-Cu/316 L stainless steel composite. The experimental and numerical investigations were carried out on the microstructure evolution as well as mechanical properties of the bonding interface. In both microstructure observations and mechanical tests, an excellent bonding quality of ODS-Cu/316 L stainless steel clad was confirmed, supporting that the explosive welding technology is a feasible way to fabricate high-quality ODS-Cu/316 L stainless steel joints. The EBSD results revealed a remarkable diversity of the grain structure at the bonding interface, including elongated grains, rectangular grains, equiaxed fine grains and columnar grains. The simulation reproduced the wavy interface observed in experiment accurately and forecasted the thermomechanical behavior of interface adequately, giving an opportunity to elucidate the observed phenomena.

Interface microstructure morphology and formation evolution mechanism of Al-1060/Cu-T2 composites fabricated by explosive welding method

ABSTRACT Aluminum–copper composite is an attractive candidate for electronic industry and power industry because of excellent electrical and thermal conductivity. In this work, the explosive welding technique was successfully employed to prepare the Al/Cu composite. The interface microstructure morphology was characterized using the optical microscopy (OM), field emission scanning electron microscopy (FSEM) and electron backscatter diffraction (EBSD). Meanwhile, the interface formation evolution process was simulated using smoothed particle hydrodynamics (SPH) method by ANSYS/LS-DYNA software. The experimental results indicated that the joining interface presents a typical wavy structure and formed melted zones in the vortex region. The formation of intermetallic compounds and strong texture were confirmed at the vortex region. The simulation results revealed the interface formation evolution characteristics and mechanism, and obtained a wavy joining interface, which are in good agreement with experimental results.

Experimental and numerical investigation on fabricating multiple plates by an energy effective explosive welding technique

An innovative explosive welding method for the fabrication of multiple plates (EWMP) was proposed to further improve the energy efficiency of explosive welding explosive charges and reduce the impact on the surrounding environment. In this method, six metal plates were placed in parallel and three composite plates were obtained through one explosion in this paper. The microstructure of the joint was analyzed by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and electron backscattering diffraction (EBSD). Compared to traditional explosive welding (TEW), the EWMP dramatically reduced the noise and vibration and increased the energy efficiency of explosives. The results showed the vibration data of EWMP were reduced by 16.7, 16.4, 2.8, and 1.5%, respectively, and at places of 3, 4, 5, and 6 m away from the explosion center, and explosive consumption of EWMP was reduced by at least half, compared to the traditional method when obtaining the same amount of welded plates. Through numerical simulation, the collision speeds of the composite plate are 610, 516, and 471 m/s, respectively, and the waveform of the composite plate is basically in coincidence with the result of the experiment.

Evaluation of Heat Transfer Performance of Double-tube Heat Exchangers with Uniporous Structure Fabricated by Explosive Welding Technique

Evaluation of Heat Transfer Performance of Double-tube Heat Exchangers with Uniporous Structure Fabricated by Explosive Welding Technique

Interfacial Microstructure of FeCoNiCrAl0.1 High Entropy Alloy and Pure Copper Prepared by Explosive Welding

The FeCoNiCrAl0.1 high entropy alloys (HEAs) and pure copper (Cu) composite plates were successfully fabricated by the explosive welding technique using two different gap distances. The interfacial microstructure, elemental distribution, grain structure of vortex zone and hardness were characterized using optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), nanoindentation and micro-hardness tester. The explosive weldability window was calculated to verify the weldability of HEAs and Cu. The results indicated that the Cu/HEA composites presented typical wavy structures without visible defects and have an excellent bonding quality. The elements mixed and formed intermetallic compounds at the vortex zones. The grains near the vortex zones showed strong deformation, and phase transformation occurred. Compared with the matrix metals, the hardness of Cu and HEAs increased near the welding interface and sharply increased to 375 HV near the vortex zone.

Experimental and numerical investigations of interface properties of Ti6Al4V/CP-Ti/Copper composite plate prepared by explosive welding

Explosive welding technique is widely used in many industries. This technique is useful to weld different kinds of metal alloys that are not easily welded by any other welding methods. Interlayer plays an important role to improve the welding quality and control energy loss during the collision process. In this paper, the Ti6Al4V plate was welded with a copper plate in the presence of a commercially pure titanium interlayer. Microstructure details of welded composite plate were observed through optical and scanning electron microscope. Interlayer-base plate interface morphology showed a wavy structure with solid melted regions inside the vortices. Moreover, the energy dispersive spectroscopy analysis in the interlayer-base interface reveals that there are some identified regions of different kinds of chemical equilibrium phases of Cu–Ti, i.e. CuTi, Cu2Ti, CuTi2, Cu4Ti, etc. To study the mechanical properties of composite plates, mechanical tests were conducted, including the tensile test, bending test, shear test and Vickers hardness test. Numerical simulation of explosive welding process was performed with coupled Smooth Particle Hydrodynamic method, Euler and Arbitrary Lagrangian-Eulerian method. The multi-physics process of explosive welding, including detonation, jetting and interface morphology, was observed with simulation. Moreover, simulated plastic strain, temperature and pressure profiles were analysed to understand the welding conditions. Simulated results show that the interlayer base plate interface was created due to the high plastic deformation and localized melting of the parent plates. At the collision point, both alloys behave like fluids, resulting in the formation of a wavy morphology with vortices, which is in good agreement with the experimental results.

Experimental and Numerical Studies on Preparation of Thin AZ31B/AA5052 Composite Plates Using Improved Explosive Welding Technique

In this work, an improved explosive welding technique was investigated to fabricate a thin Mg/Al plate, where an additional thin aluminum sheet was used as a buffer layer between the explosive and the Al plate, and the Mg plate was rigidly constrained by a steel plate to avoid excessive deformation. Moreover, the welding parameters were optimized using theoretical analysis and numerical simulation, and the interfacial behavior was simulated using the SPH method. The bonding properties of the achieved joints were investigated using microstructure observation and mechanical tests. It was concluded that this technique is an effective method for producing a thin Mg/Al composite plate. In both morphology observation and mechanical tests, an excellent bonding quality was confirmed. In addition, smoothed particle hydrodynamics (SPH) simulation revealed an extreme condition of local high temperature and plastic strain in the welding process, and the characteristic parameters of waves obtained using simulation are well congruous with the experiment.

Research on the interfacial microstructure of three-layered stainless steel/Ti/low-carbon steel composite prepared by explosive welding

ABSTRACT The stainless steel/Ti/low-carbon steel trimetallic composite plate was successfully fabricated by the explosive welding technique using honeycomb aluminum structure low detonation velocity emulsion explosive. The interfacial microstructure characterizations, elemental distribution, phase transformation and hardness were characterized using optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and micro-hardness tester. The results indicated that the trimetallic sheet of stainless steel/Ti/low-carbon steel was successfully welded without visible defects and have an excellent bonding quality. The Ti/;ow-carbon steel joining interface had a typical wavy structure and formed about 3 µm thick transition layer. The stainless steel/Ti joining interface had an almost flat structure; meanwhile, the phase transformation of Fe and Ti and the texture occurred at the joining interfaces. The hardness increased near the welding interface and sharply increased in the melted zones.

Towards a better understanding of the phase transformations in explosively welded copper to titanium sheets

The influence of post-process annealing on the growth kinetics of the intermetallic phases and mechanical properties of titanium/copper bimetallic sheets were analysed using scanning and transmission electron microscopies, X-ray synchrotron radiation, and mechanical testing. In order to weld two metal sheets, an explosive welding technique was utilised. Subsequently, the clads were subjected to post-weld annealing at 973 K from 0.25 to 1000 h. In the bonded state, the interface exhibited a wavy structure with only a small amount of solidified melt zones, composed of non-equilibrium phases of variable chemical compositions. After short annealing times (<1 h) these non-equilibrium phases transformed into equilibrium phases of TiCu4 and Ti3Cu4via spinodal decomposition. For longer annealing times (>1 h), the growth of four intermetallic layers: Ti2Cu, TiCu, Ti3Cu4, and TiCu4 situated along the entire interface is predominant. It was observed that the phases enriched with Cu and Ti were situated near the Cu and Ti parent sheets, respectively. The nano-hardness of the intermetallic phases decreased as the Ti content increased, whereas the Young's modulus reached its highest values for phases with equiatomic or close-to-equiatomic composition.

Preparation of laminated structure in AZ31 magnesium alloy by explosive welding

Magnesium alloys, because of their unique compositions, microstructures, and adjustable properties, have attracted attentions for years. Up to date, many magnesium alloys fabricated by different methods have been reported. Though great improvements have been achieved, the extreme conditions were rarely applied to prepare not only magnesium alloys, but also other metals. Here, we apply the explosive welding technique to make microstructure tailoring for magnesium alloy. The explosive welding technique can produce the shock compression condition, which is involved high pressure, high temperature and high strain rate. With this method, a laminated structure has been formed in the prepared AZ31 plate with five rolled sheets being joined at an extreme conditions resulting from the detonation of explosive. Note that a significant grain refinement with average grain size of ~430 nm in interfaces was obtained due to severe deformation and brings about strong strengthening effect which was illustrated by microhardness testing results. Based on the microstructure characterizatioon and microhardness testing, this work renders one more method in tailoring the mechanical properties of magnesium alloys by using explosive welding method.

The Interface Microstructure and Mechanical Properties of Niobium-316L Stainless Steel Explosively Welded Composite Plate

In order to manufacture stainless steel helium vessels for the superconducting radio frequency (SRF) cavities, niobium-316L stainless steel composite plates were fabricated by explosive welding technique. The microstructure and mechanical properties of the composite plates were investigated both right after explosive welding and after annealing. The microstructure measurement results demonstrated that there was not any brittle intermetallic layer formed nor any diffusion phenomenon observed after heat treatment processes. Due to the plastic deformation and work hardening near the interface, the hardness of the composite plates was higher near the bonding interface than inside the bulk metal regions. Meanwhile, ultimate tensile strength and shear strength of the composite plate reached their maximum values when the sample was annealed at 873 K for 10 h at room temperature. Charpy impact test results at liquid helium results showed that the toughness of composite plate meets the requirements from the SRF cavities’ helium vessels fabrication.

Joining AlCoCrFeNi high entropy alloys and Al-6061 by explosive welding method

High entropy alloy (HEA) is an emerging class of materials that shows promising potential for many applications. Numerous HEAs have been synthesized and characterized over the past twenty years, however only limited researches have been done on the welding process of HEAs. In this research, AlCoCrFeNi High Entropy Alloys and Al-6061 plates are welded by using the explosive welding technique. In order to characterize the morphology and the composition of the compound, a scanning electron microscope was utilized. The weldability window was calculated in order to verify the weldabilty of the AlCoCrFeNi to Al-6061, and three different conditions were selected to perform the experiments. In all the experiments the AlCoCrFeNi and Al-6061 were properly welded together. However, some cracks were observed in the welded samples obtained in high velocity collision. The results suggest that the explosive welding technique is potentially a good method for joining high entropy alloys to other metals.