Explosive Welded Joints Research Articles

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.

Neuro-Fuzzy Technique for Micro-hardness Evaluation of Explosive Welded Joints

Neuro-Fuzzy Technique for Micro-hardness Evaluation of Explosive Welded Joints

Mechanical buckling analysis of explosive welded joints used in shipbuilding

Mechanical buckling analysis of explosive welded joints used in shipbuilding

Characterization of Vacuum Explosive Welded Joints between Titanium and Stainless Steel for Vacuum Applications

A two-layered vacuum explosive welded (EXW) plate, consisting of titanium-grade 1/stainless steel 304L (Ti/304L), was investigated for vacuum applications. The interface of the Ti/304L displayed a wavy shape characteristic of the EXW method, which reflects the existence of mass transfer during bonding. The aim of this study was to examine the feasibility of using Ti/304L EXW joints for vacuum application. The Ti/304L EXW plate was examined by non-destructive and destructive metallurgical methods, including visual testing, scanning acoustic testing, light microscopy and metallography, SEM-EDS examination, microindentation hardness measurements, ram tensile test, fractography, and leak testing. According to the metallurgical testing methods, the formation of brittle intermetallic phases took place adjacent to the bonding interface. The intermetallic phases formed at the interface of the Ti/304L, behave as the weakest part in the joint, and determine the brittle type of fracture received under tensile stresses. The measured typical tensile strength of the joint is around 300 MPa, similar to that of the Ti 1 alloy. Based on the leak test results, the examined EXW Ti/304L components were found to be feasible for vacuum applications.

Multilayer Cu/Al/Cu explosive welded joints: Characterizing heat treatment effect on the interface microstructure and mechanical properties

In the current research, microstructure evolution and mechanical properties of multilayer Cu/Al/Cu explosive welded joints were studied at upper and lower interfaces after heat treatment. To investigate the effects of time and temperature on joints, welded samples were annealed at 300 and 400 °C for different soaking times of 30 min and 20 h. Joints were analyzed by optical microscope (OM), scanning electron microscope (SEM), microhardness and shear strength tests along with interface composition change by means of energy dispersive spectroscopy (EDS). Results revealed that the average thickness of diffusion layer had been increased by enhancement of treatment variables. This was associated with the microhardness of diffusion layer at both interfaces. Meanwhile, tensile-shear strengths of joints were reduced after annealing due to the layer thickness increment of intermetallic compounds (IMCs). Microchemical analyses proved that not only layer thickness experienced alteration, but also, types of IMCs had evolution at interfaces. Doing this, evolution of diverse compounds of AlCu, Al2Cu, Al3Cu, and Al3Cu2 were experienced. Obtained results elucidated that the thickness of diffusion layer had direct correlation with both temperature and time of applied thermal cycles.

Non linear finite element simulation of explosive welded joints of dissimilar metals for shipbuilding applications

A procedure to simulate the non-linear behavior of explosion welded joints used for shipbuilding applications, starting only from hardness measurements, was developed. The explosion welded joints consist of three different materials: ASTM A516 structural steel, AA5086 aluminum alloy and an intermediate layer of pure aluminum. Three point bending tests were carried out on explosion welded joints with and without an initial notch. The Digital Image Correlation, which is a non-contact full-field technique, was applied in order to measure the displacement and strain patterns of the different metals during the bending tests. Non - linear finite element analyses were performed. The stress-strain curves of the materials, applied in the finite element model, were obtained using Ramberg Osgood type equations and considering the results of the micro-hardness measurements, which were correlated to the mechanical properties of the different materials. The finite element model was validated experimentally, comparing the results with the measurements obtained using the Digital Image Correlation technique. Furthermore, the procedure was extended to a specimen with an initial notch, for which the FE results were compared to the experimental tests.

Full-field analysis of AL/FE explosive welded joints for shipbuilding applications

Nowadays explosion weld is widely used in marine structures, thanks to its reliability. AL/FE explosive welded joints, used in shipbuilding applications, were investigated in this research activity. Static and fatigue bending tests were carried out on rectangular specimens made of ASTM A516 low carbon steel, clad by explosion welding with A5086 aluminum alloy and provided with an intermediate layer of pure aluminum. Two full-field techniques were applied during the bending tests: Digital Image Correlation and Infrared Thermography. The digital image correlation technique allowed determining the displacement and strain fields showing that the aluminium side has a higher strain with respect to the steel side, and Infrared Thermography was used to detect the superficial temperature of the specimen allowing the determination of the fatigue limit. The fatigue limit values, predicted using the Thermographic Method during static and fatigue tests, are in good agreement with the experimental values of the fatigue limit.

Ultrasonic Flaw Detection for Quality Assessment of Explosively Clad Plates

The aim of this work was to study more thoroughly all problems relating to the evaluation of material defects connected with plate quality before and after explosive cladding. During testing great attention was paid to material defects in plates, the reasons for their appearance and possibility of detecting them by means of ultrasonic technique. It was most important to find out which defects were especially dangerous. The results of ultrasonic testing that relate to the quality of initial steel plates are described. Modelled defects of various sizes are ultrasonically tested and analysed. The properties of explosive welded joints and cases of cracks in clad plates are tested. All these data can be helpful in the context of working out criteria relating to the selection of initial plates for cladding.

Effect of Heat Treatment on the Microstructure and Microchemistry of Explosive Welded Joints of Ti-5Ta-1.8Nb and 304L SS

Explosive welding process was used for joining Ti-5Ta-1.8Nb alloy to 304L austenitic stainless steel to avoid the formation of intermetallic phases at the interface which otherwise form in fusion welding processes. Both X-ray diffraction and electron microprobe based analysis showed the absence of intermetallic phases at the weld interface within their detection limits. Strain induced phase transformation due to the deformation induced by explosive welding was observed in both the base materials. The 'as received' explosive joints were further heat treated at 873 and 1073 K for durations in the range of 1 to 20 h to select appropriate temperature for further processing subsequent to welding. Detailed analysis using electron microprobe showed considerable microstructural and micro chemical modification at the weld interface due to inter-diffusion of Fe, Ti, Cr and Ni. The width and number of reaction zones varied as a function of heat treatment temperature and time. From the experiments, it was inferred that even the lowest temperature-time combination, i.e. 873 K-1h, is not suitable for heat treatment of explosive joints of Ti-5Ta-1.8Nb/SS 304L, and further lowering of the process temperature is required.

Effect of Heat Treatment on the Microstructure and Microchemistry of Explosive Welded Joints of Ti-5Ta-1.8Nb and 304L SS

Explosive welding process was used for joining Ti-5Ta-1.8Nb alloy to 304L austenitic stainless steel to avoid the formation of intermetallic phases at the interface which otherwise form in fusion welding processes. Both X-ray diffraction and electron microprobe based analysis showed the absence of intermetallic phases at the weld interface within their detection limits. Strain induced phase transformation due to the deformation induced by explosive welding was observed in both the base materials. The 'as received' explosive joints were further heat treated at 873 and 1073 K for durations in the range of 1 to 20 h to select appropriate temperature for further processing subsequent to welding. Detailed analysis using electron microprobe showed considerable microstructural and micro chemical modification at the weld interface due to inter-diffusion of Fe, Ti, Cr and Ni. The width and number of reaction zones varied as a function of heat treatment temperature and time. From the experiments, it was inferred that even the lowest temperature-time combination, i.e. 873 K-1h, is not suitable for heat treatment of explosive joints of Ti-5Ta-1.8Nb/SS 304L, and further lowering of the process temperature is required.

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.

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.

摩擦圧接および爆発圧接したアルミニウムとチタンの接合界面

Bonding interfaces of friction- and explosive-welded aluminum-titanium joints, before and after annealing for 1h at temperatures between 723 and 923K, were examined by tensile test for bonding strength, and by optical and electron micrographies, and EPMA for phases in interfacial reaction-layers. Results obtained are as follows:(1) Bonding strength of both friction- and explosive-welded joints in the as-welded and annealed states is higher than the tensile strength of aluminum matrix in each specimen. Thus, fracture occurs in the aluminum matrix.(2) The interfacial reaction layer consists of only Al3Ti in the case of friction-welded joint, and Al3Ti and AlTi in the explosive-welded joint.(3) These phases are so stable that the thickness of the layer is kept almost the same by the annealing.