Explosive Welding Research Articles

Comprehensive investigation of microstructural inhomogeneity in the bonding zone of explosive-welded AISI 410S/A283GrD composite

ABSTRACT This study investigates the microstructural inhomogeneity in the bonding zone of AISI 410S/A283GrD explosive-welded plate by experiment and simulation. The interfacial microstructure and chemical components are investigated, and the difference of grain size across the peak and valley is studied separately. Due to severe plastic deformation and work hardening during the explosive welding process, the microhardness of the combination area adjacent to the interface is higher than that of parent plates. The wavy interface of the numerical simulation is in good agreement with the experimental observation. The numerical simulation results, such as distribution of shear stress, pressure, and effective plastic strain rate of the model are investigated, and the forming reason of interfacial microstructures, are explained by these results.

Non-linear finite element analysis of a Ti6Al4V/Inconel 625 joint obtained by explosion welding for sub-sea applications

Industries have shown interest in the use of dissimilar metals to make corrosion-resistant materials combined with good mechanical properties in marine environments. Explosive welding can be considered a good method for joining dissimilar materials to prevent galvanic corrosion. The aim of the present study was to simulate the non-linear behaviour of a Ti6Al4V/Inconel 625 welded joint obtained by explosion welding from the values of the tensile ultimate strength and yielding strength of the parent materials. The present study compared the stress-strain curve from tensile loading obtained by the non-linear finite element analysis with the experimental stress-strain curve of a bimetallic joint. The applied method provides useful information for the development of models and the prediction of the structural behaviour of Ti6Al4V/Inconel 625 explosive welded joints.

Characterization of Shock Wave Damages in Explosion Welded Mo/Cu Clads

The shock wave damage during explosive welding has not been reported in a flyer Mo plate of the Mo/Cu clads. However, it would be an inevitable problem in group VI elements. This study was aimed to characterize the shock wave damage in the Mo plate, that is less brittle than a W plate, of explosive welded Mo/Cu clads. Cladding at low horizontal collision velocities leading to high collision angles was expected to enhance the shock wave damage, and the clads resulted in less elongation in bending tests. On the other hand, in the clads obtained at high horizontal collision velocities (HCVs) with low collision angles, their bending elongation increased significantly. The shock wave damage penetrated from the surface of a Mo plate to the Mo/Cu interface, and thus reducing thickness of a Mo plate of bending specimens increased bending plastic strain. The shock wave damage is associated with kinetic energy imparted to the flyer Mo plate, and thus loss of kinetic energy due to formation of an intermediate layer at the interface and reducing thickness of a flyer Mo plate would be very helpful for decrease of shock wave damage.

Influence of element distribution on mechanical properties in the bonding zone of explosively welded steels

A melt pocket in the bonding zone of medium carbon steel bonded on low-carbon steel by explosive welding was investigated by laser assisted atom probe tomography. It was found that the structure is nanocrystalline and (sub-) grain boundaries are enriched with carbon. High hardness values in the melt pocket are attributed to a combination of (sub-) grain size and carbon distribution.

Nano Identification and Tribo Testing of Explosive Welding Copper/Brass

Nano Identification and Tribo Testing of Explosive Welding Copper/Brass

Brass/Invar bimetal by explosive welding

Thermostatic bimetals (thermobimetals) are materials consisting of layers with different coefficients of thermal expansion. The layer with a higher coefficient of thermal expansion is called active, with a lower—passive. Invar (Ni-Fe alloy) is mainly used as the passive layer and brass (Cu-Zn alloy) as the active layer. Strong adhesion of the layers along the entire length is one of the main requirements for all grades of thermobimetals. In this study, an Invar/brass thermobimetal plate was obtained by explosive welding (EW). The plate was subjected to metallographic, ultrasonic, and mechanical examination. Scanning electron microscope (SEM) showed that the weld interface had the form of uniform waves over its entire surface. Also, melted zones in the crests and troughs of the waves were observed. Energy-dispersive spectroscopy (EDS) line scanning showed that the melted zones consisted of a disordered Cu–Zn–Fe–Ni solid solution (predominately, of Zn and Cu) and undissolved Invar particles. The average microhardness of the melted zones was 350 HV. A 3-mm-wide strengthened zone along the weld interface was observed. The average tear strength of the Invar/brass weld joint was 550 MPa, which is higher than that of the individual initial metals. The bending testing has shown that the thermobimetal plate is resistant to delamination, which indicates the satisfactory quality of the weld joint. Based on the results obtained from this study, it can be concluded that EW can be used to produce high-quality Invar/brass thermobimetal plates.

The Interface Zone of Explosively Welded Titanium/Steel after Short-Term Heat Treatment

This work presents a detailed description of a bonding zone of explosively welded Ti/steel clads subjected to stress relief annealing, applied in order to improve the plasticity of the final product. The typical joint formed by the welding process possesses a characteristic wavy interface with melted regions observed mainly at the crest regions of waves. The interface of Ti/steel clads before and after annealing was previously investigated mostly in respect to the melted regions. Here, a sharp interface between the waves was analyzed in detail. The obtained results indicate that the microstructure of a transition zone of that area is different along the width. After the heat treatment at 600 °C for 1.5 hours, titanium carbide (TiC) together with α-Fe phase forms at the interface in local areas of relatively wide interlayer (~ 1 µm), while for most of the sharp interface, a much thinner zone up to about 400 nm, formed by four sublayers containing intermetallic phase and carbides, is present. This confirms that carbon diffusion induced by applied heat treatment significantly influences the final microstructure of the Ti/steel interface zone. Side bending tests confirmed high plasticity of welds after applied heat treatment; however, the microhardness measurements indicated that the strengthening of the steel in the vicinity of the interface had not been removed completely.

Effect of Secondary Explosive Welding on Microstructure and Mechanical Properties of 10CrNi3MoV Steel-Based Composite Plates

Effect of Secondary Explosive Welding on Microstructure and Mechanical Properties of 10CrNi3MoV Steel-Based Composite Plates

Effect of explosive welding parameters on Al/LCS interface cladded by low velocity of detonation explosive welding (LVEW) process

Interfacial properties govern the metallurgical and mechanical behaviour of welded specimens. Hence to study the effect of different parameters on weld interface is an important aspect to bring the desired output properties for various applications. In this study, a newly developed low velocity of detonation explosive welding (LVEW) process was applied to clad aluminium (Al) and low carbon steel (LCS) plates. Loading ratio (R) and stand-off distance (SD) were adopted for this study, as these two mostly affect the welding behaviour and act as important welding parameters. Microstructural examination as well as mechanical tests were performed. Three kinds of morphology were observed at the weld interface, i.e. large waves (LW), small irregular waves (SIW) and smooth flat interface (SFI), where SIW and SFI contribute interface devoid of voids, intermetallic and melting pockets. But at higher R and SD, AlFe and Al2Fe intermetallic were observed in non-continuous form in micron range. Elemental analysis confirmed the local diffusion with very thin diffusion thickness of 0.8–2 μm. Micro-hardness profile discloses the shock hardening effects across the vicinity of the weld interface, where an increase in hardness value was above the parent value. Chisel test and shear strength test also confirmed the good quality of bonding, while in shear fracture study, dimple structure was dominated in all the specimens. All these observations concluded that for cladding Al/LCS, LVEW process is best suitable and further, the practicability of these welded plates was checked by fabricating components like bi-metallic O-ring (push-fit type), hollow cylinder and bolts.

Особливості формування структури коаксіальних з’єднань міді та алюмінію при зварюванні вибухом з вакуумуванням зварювального проміжку

Особливості формування структури коаксіальних з’єднань міді та алюмінію при зварюванні вибухом з вакуумуванням зварювального проміжку

Features of formation of structure of coaxial joints of copper and aluminium in explosion welding with vacuuming of welding gap

Features of formation of structure of coaxial joints of copper and aluminium in explosion welding with vacuuming of welding gap

FEATURES OF STRUCTURE FORMATION IN EXPLOSION WELDED BIMETAL STEEL 20 + STAINLESS STEEL 50CR15MO2V AFTER LONG HIGH-TEMPERATURE HEATING

The results of studies of the structure in the joint zone of stainless steel 50Cr15Мo2V with carbon steel 20 after explosion welding and subsequent heat treatment at a temperature of 1000 ° C and holding times of 5-20 hours are presented. The formation of a continuous diffusion layer in the joint zone is shown, the thickness of which depends on the holding time.

Microstructure development during explosive welding of metal foil：morphologies, mechanical behaviors and mechanisms

The fundamental evolution mechanisms of many important phenomena accompanying explosive welding of metal foils remain a subject of open discussion, due to the extreme difficulties of in-situ observations. In this work, a comprehensive study combined SPH (smoothed particles hydrodynamics) simulation and advanced characterization was performed to investigate the interfacial evolutions, nano-mechanical properties, and the associated governing mechanisms in Cu foil/Fe welding system. Based on the simulation results, a detailed evolution model of the wave formation was given, and a new explanation for the vortex formation was proposed. The microstructure analyses revealed that the grain structures adjacent to the joining interface were dramatically changed, where two different morphologies of equiaxed and columnar grains were detected at Fe and Cu side, respectively, and the vortex area was built of ultra-fine equiaxed nanometer grains. These microstructure changes were correlated very well with the nano-mechanical properties, and the perplexing evolution processes can be explained by dynamic recovery and recrystallization accompanied by different degrees of crystal growth and deformation. The predicted widths of recrystallization layer and hardened layer agree well with the experimental results, suggesting that the SPH simulation allows predicting the microstructure evolution during the high speed impact welding process in a quantitative way.

Microstructure and mechanical properties of the Ag/316L composite plate fabricated by explosive welding

In the present research, the Ag/316L composite plate was fabricated by the explosive welding. Its microstructure and mechanical properties were studied and the results reveal that the explosively welded Ag/316L composite plate has typical interfacial wavy structure which has the average period of 900 μm and average height of 400 μm. Along the Ag/316L composite interface, the transition layer, melted region and Ag rich layer are formed discontinuously. The γ-Fe particles are enveloped in the melted region with relatively homogeneous distribution. Moreover, some Fe2O3 oxides are formed in the melted region. The violent collision by explosive welding has resulted in great deformation in the region adjacent to the interface, which promotes the thorough recrystallization in Ag side and abundant substructures in 316L stainless steel side. Such a microstructure evolution increases the microhardness of the area adjacent to the interface. The Ag/316L composite plate exhibits good bending properties without any interfacial crack, but the discontinuously distributed oxides are formed along the interface, which would be detrimental to the deformability by acting as the crack nucleation. The Ag/316L composite plate possesses the average yield strength, ultimate tensile strength and elongation of 350 MPa, 690 MPa and 39 %, respectively. And its average shear strength is 177 MPa. Such mechanical properties should be attributed its good interfacial structure and refined grains.

Calculation of the optimal corrugation of the plate surface for explosive welding

This article suggests profiling the surface of one of the welded plates in a special way during explosion welding. The principle and method of calculating the profile of the plate based on the materials and welding speeds of the plates are given. It is assumed that such profiling of the surface of the plate will allow to obtain more durable welded joints and even perform welding at a speed below the minimum collision speed for welding plates with smooth surfaces. As an example, a full calculation of plate profiling for specific collision parameters of welded plates is given.

Experimental and theoretical study of dynamic bend angle in the explosive welding process

Dynamic bend angle (β) is an important parameter that should satisfy the range defined by the weldability window for successful joining in the explosive welding process. In this manuscript, we studied the dynamic bend angle (β) for the newly developed low velocity of detonation explosive welding (LVEW) process theoretically and then experimentally with the help of flash X-ray radiography (FXR) technique. The FXR system captured the real-time image of the event where proper explosive welding process with clear flight shape and appropriate collision bend angle was observed. The FXR results were in good agreement with numerically calculated β values and demonstrated the suitability of LVEW process for joining of dissimilar metal plates. This was further justified by phased array-based ultrasonic testing (PAUT) results where complete bonding area with slight non-bonded area was observed across the edges of the welded metal plate.

Interfacial Morphology and Bonding Mechanism of Explosive Weld Joints

Interfacial structure greatly affects the mechanical properties of laminated plates. However, the critical material properties that impact the interfacial morphology, appearance, and associated bonding mechanism of explosive welded plates are still unknown. In this paper, the same base plate (AZ31B alloy) and different flyer metals (aluminum alloy, copper, and stainless steel) were used to investigate interfacial morphology and structure. SEM and TEM results showed that typical sine wave, wave-like, and half-wave-like interfaces were found at the bonding interfaces of Al/Mg, Cu/Mg and SS/Mg clad plates, respectively. The different interfacial morphologies were mainly due to the differences in hardness and yield strength between the flyer and base metals. The results of the microstructural distribution at the bonding interface indicated metallurgical bonding, instead of the commonly believed solid-state bonding, in the explosive welded clad plate. In addition, the shear strength of the bonding interface of the explosive welded Al/Mg, Cu/Mg and SS/Mg clad plates can reach up to 201.2 MPa, 147.8 MPa, and 128.4 MPa, respectively. The proposed research provides the design basis for laminated composite metal plates fabrication by explosive welding technology.

Microstructure Development in the Bonding Zone of Explosively Welded Ti and Cu Sheets

The interplay of various hardening and softening processes during explosive welding and post-processing annealing have been analysed in titanium/copper bimetallic sheets using scanning electron microscopy and microhardness measurements. Severe plastic deformation and intermetallics’ formation are typical processes leading to hardening, whereas dynamic/static recrystallization and the transformation of amorphous phases into crystalline ones lead to softening. In the as-welded state the interfacial layers of both parent sheets are severely deformed. However, they can undergo intense recrystalization in areas near large melted zones. Inside the melted zones a wide variety of chemical compositions can be detected, however, most of the phases do not appear in the Ti-Cu equilibrium phase diagram. The post-processing annealing at 973 K for 1 h leads to full recrystallization of severely deformed layers of parent sheets and transforms the non-equilibrium phases forming melted zone into the equilibrium TiCu4 and Ti3Cu4 ones via spinodal decomposition. Simultaneously, the growth of four intermetallic layers: Ti2Cu, TiCu, Ti3Cu4, TiCu4 situated along the whole interface was detected.

Interface Microstructure and Phase Constitution of AA1060/TA2/SS30408 Trimetallic Composites Fabricated by Explosive Welding

Interface Microstructure and Phase Constitution of AA1060/TA2/SS30408 Trimetallic Composites Fabricated by Explosive Welding

Features of acoustic control of solidity of connection of large-sized bimetallic plates of steel-titanium system, obtained by explosion welding

Features of acoustic control of solidity of connection of large-sized bimetallic plates of steel-titanium system, obtained by explosion welding