Showing papers in "Science and Technology of Welding and Joining in 2019"
TL;DR: In this paper, the authors provide a comprehensive insight on the BTFSW, focusing on tool material selection, design features of shoulder and pin surfaces, microstructure evolution, mechanical characterisation, derivatives, and challenges in this technique.
Abstract: Friction stir welding is a solid-state welding technique for joining similar and dissimilar material. Bobbin tool friction stir welding (BTFSW) is a variant of the conventional friction stir welding process (CFSW). Compared with conventional FSW, BTFSW eliminates all limitations of CFSW using a two shoulders configuration. Now, the need has arisen to review the work done on BTFSW to provide broader aspects of the technique to researchers. This paper aims at providing comprehensive insight on the BTFSW. The paper pays critical attention to tool material selection, design features of shoulder and pin surfaces, microstructure evolution, mechanical characterisation, derivatives, and challenges in this technique. Further, welding defects and future scope of BTFSW are also addressed in this paper.
63 citations
TL;DR: In this paper, cold spray (CS) is a new solid state coating technique that has attracted considerable attention as it is quite suitable for mass production of metallic materials or metal matrix composites.
Abstract: Cold spray (CS) is a new solid state coating technique that has attracted considerable attention as it is quite suitable for mass production of metallic materials or metal matrix composites. More r...
54 citations
TL;DR: In this paper, functionally graded materials of Stainless Steel 316L and Inconel 625 were fabricated using Directed Energy Deposition (DED) using an intermediate layer in between the two materials.
Abstract: In this work, functionally graded materials of Stainless Steel 316L and Inconel 625 were fabricated using Directed Energy Deposition. Intermediate layers were built in between of SS316L and IN625. ...
51 citations
TL;DR: In this article, the steel/zinc system creates the potential for liquid metal embrittlemen, which is a potential problem in automotive structural components, such as automotive structural component.
Abstract: Advanced high strength steels used in automotive structural components are commonly protected using zinc coatings. However, the steel/zinc system creates the potential for liquid metal embrittlemen...
50 citations
TL;DR: In this paper, a thin Cu-40Zn foil as marker was inserted into the butting surface of two friction stir welders to measure the distortion of the marker material.
Abstract: The strain and strain rate during friction stir welding was evaluated by measuring the distortion of the marker material. A thin Cu-40Zn foil as marker was inserted into the butting surface of two ...
49 citations
TL;DR: In this paper, the authors proposed a functional graded component for severe and critical service conditions, thanks to the possibility of achieving different complementary material properties within the same service conditions and with different complementary materials properties.
Abstract: Functionally graded components are usually preferred for severe and critical service conditions, thanks to the possibility of achieving different complementary material properties within the same s...
49 citations
TL;DR: In this article, active interpass cooling using compressed CO2 was innovatively employed in the wire arc additively manufactured Ti6Al4V process with the aim of mitigating part distortion, and a comparat...
Abstract: In this study, active interpass cooling using compressed CO2 was innovatively employed in the wire arc additively manufactured Ti6Al4V process with the aim of mitigating part distortion. A comparat...
45 citations
TL;DR: In this paper, a 3D print device equipped with a cold metal transfer welding source was used to simulate the formation of 3D microstructures of aluminium deposits. And the effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters.
Abstract: 4043 aluminium deposits were elaborated using a 3D print device equipped with a Cold Metal Transfer welding source. Two sets of process parameters leading to different average powers were compared in order to establish the relations between the powers and energies produced and the geometrical characteristics of the deposits. The effects of the travel speed and layer superposition on the transfer mechanisms as well as on the geometrical characteristics of the deposits were discussed for both sets of parameters. Finally, the formed microstructures were analysed and the porosity defects were quantified and discussed with regard to the heat input characteristics and the solidification conditions.
43 citations
TL;DR: The joining of a strong and a light metal such as; steel and magnesium alloys (Mg alloys) is much-needed demand for reducing the weight of the vehicles and other structures in various engin...
Abstract: The joining of a strong and a light metal such as; steel and magnesium alloys (Mg alloys) is much-needed demand for reducing the weight of the vehicles and other structures in various engin...
41 citations
TL;DR: Titanium alloy Ti5553 (Ti-5Al-5Mo-5V-3Cr) is an excellent candidate for structural applications and additive manufacturing processes, since, unlike Ti6Al4V, when built via selective laser melting...
Abstract: Titanium alloy Ti5553 (Ti-5Al-5Mo-5V-3Cr) is an excellent candidate for structural applications and additive manufacturing processes, since, unlike Ti6Al4 V, when built via selective laser melting ...
41 citations
TL;DR: In this article, fracture modes of dissimilar lap welds produced by friction stir scribe technology were studied under tensile shear loading, and three fracture modes were observed for zone A fracture.
Abstract: Under tensile shear loading, fracture modes of dissimilar lap welds produced by friction stir scribe technology were studied. Three fracture modes were observed. For zone A fracture, the initial cr...
TL;DR: In this article, WC reinforced Ni-based composite coatings with Y2O3 addition were deposited on Ti-6Al-4V titanium substrate by laser cladding and the phases, microstructure, microhardness and wear resi...
Abstract: In this study, WC reinforced Ni-based composite coatings with Y2O3 addition were deposited on Ti-6Al-4V titanium substrate by laser cladding. The phases, microstructure, microhardness and wear resi...
TL;DR: In this article, a hybrid technique integrating wire arc additive manufacturing (WAAM) and milling was studied using Al5Si aluminium alloy, and the results showed both the surface roughness and the machining allowance.
Abstract: A hybrid technique integrating wire arc additive manufacturing (WAAM) and milling was studied using Al5Si aluminium alloy. The results showed both the surface roughness and the machining allowance ...
TL;DR: In this paper, the effects of atmospheric contamination on wire arc additively manufactured (WAAM) components were studied by producing AM multilayer parts under controlled conditions. Gas impurity levels were investigated.
Abstract: The effects of atmospheric contamination on wire arc additively manufactured (WAAM) components were studied by producing AM multilayer parts under controlled conditions. Gas impurity levels...
TL;DR: In this article, the grain structure of laser welded AlMgSi-alloys was varied by adapting the welding parameters and alloying additives, and the hot cracking susceptibility was determined by the critical strain rate, m...
Abstract: The grain structure of laser welded AlMgSi-alloys was varied by adapting the welding parameters and alloying additives. The hot cracking susceptibility was determined by the critical strain rate, m...
TL;DR: In this paper, the thermal fluid dynamics has not been well understood in laser wire deposition, and the authors systematically invest in the thermal flow dynamics of laser wire in order to understand the most favorable deposition pattern.
Abstract: Liquid bridge transfer mode is most favourable deposition pattern in laser wire deposition However, the thermal fluid dynamics has not been well understood In this paper, we systematically invest
TL;DR: In this article, the phase transformations during bra-brazed joints are investigated. But the authors focus on the intermetallic phase formation and do not address the phase transformation of the brazed joint itself.
Abstract: Fundamental understanding of the intermetallic phase formation is the key for enhancing the robustness and reliability of the brazed joints. The paper addresses the phase transformations during bra...
TL;DR: Selective laser melting involves manufacturing of a part layer-by-layer by localised melting and solidification of metal powders as discussed by the authors, where the geometry, composition, structure and property of the so...
Abstract: Selective laser melting involves manufacturing of a part layer-by-layer by localised melting and solidification of metal powders. The geometry, composition, structure and property of the so...
TL;DR: A printability database can help in the selection of a printing process-alloy combination to reduce, and in some cases avoid, common defects in printed parts as discussed by the authors, which can also be used to improve the quality of printed parts.
Abstract: A printability database can help in the selection of a printing process-alloy combination to reduce, and in some cases avoid, common defects in printed parts. The extensive testing of parts...
TL;DR: In this article, defect-free joints were produced in 2.0mm thick 7075-T6 Al alloy by refill friction stir spot welding using a modified tool, which was evaluated in terms of microstructure, inte...
Abstract: Defect-free joints were produced in 2.0 mm thick 7075-T6 Al alloy by refill friction stir spot welding using a modified tool. Weld performance was evaluated in terms of microstructure, inte...
TL;DR: In this article, the effects of oscillating diameter (D) and frequency (f) on weld surface and cross-sectional morphologies were investigated in laser welding of AA6061 aluminium alloy with circular beam oscillation.
Abstract: Effects of oscillating diameter (D) and frequency (f) on weld surface and cross-sectional morphologies were investigated in laser welding of AA6061 aluminium alloy with circular beam oscillation. W...
TL;DR: In this article, the dissimilar welds between aluminium alloy, A6061-T6, and stainless steel, type 304, were fabricated by a friction stir welding (FSW) technique.
Abstract: The dissimilar welds between aluminium (Al) alloy, A6061-T6, and stainless steel, type 304, were fabricated by a friction stir welding (FSW) technique. The FSW tool was offset to Al side an...
TL;DR: In this article, the authors proposed a solid-state manufacturing process for making complex components using ultrasonic additive manufacturing (UAM) for fabrication of ferritic (body centered cubic) steels.
Abstract: Ultrasonic additive manufacturing (UAM) is a solid-state manufacturing process for making complex components. However, fabrication of ferritic (body centered cubic) steels has been challeng...
TL;DR: In this paper, a similar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire.
Abstract: Dissimilar joint between 304L austenitic stainless steel and low-alloy steel 16Mn was underwater wet welded using self-shielded nickel-based tubular wire. Microstructure, mechanical properties and corrosion behaviour of dissimilar welded joints were discussed. Ni-based weld metal was fully austenitic with well-developed columnar sub-grains. Type II boundary existed between Ni-based weld metal and ferritic base metal in underwater welds similar to that in air welds. Major alloying elements distributed non-uniformly across the austenitic weld metal/16Mn interface. Maximum hardness values in wet welding appeared in a coarse-grained heat-affected zone at the 16Mn side, which possessed very low impact toughness. Underwater Ni-based welded joints fractured at Ni-based weld metal under tensile test. Ni-based weld metal had favourable corrosion resistance similar to 304L base metal.
TL;DR: In this article, a flexible multi-point support fixture (FMSF) was developed as an in-process distortion control technique, which allows the distortion to be suppressed by adjusting the restraining force imposed onto the substrate dynamically as the number of layers increases.
Abstract: Distortion induced by non-uniform thermal gradients is one of the major constraints in wire and arc additive manufacturing. A novel flexible multi-point support fixture (FMSF) featured by reconfigured working surface and controllable restraining force is developed as an in-process distortion control technique. FMSF allows the distortion to be suppressed by adjusting the restraining force imposed onto the substrate dynamically as the number of layers increases. Both simulations and experiments are conducted to verify its effectiveness and compare it with other common restraint forms including clamping and pre-springing. The multi-layer deposition results show that a reduction of 96.3% in angular distortion and 86.5% in longitudinal bending distortion are obtained with FMSF, which exhibits great superiority over clamping and pre-springing.
TL;DR: In this article, two transformation pathways were employed to improve the phase balance in the fusion zone (FZ) of 2304 duplex stainless steel during resistance spot welding: (i) downsloping current modif...
Abstract: Two different transformation pathways were employed to improve the phase balance in the fusion zone (FZ) of 2304 duplex stainless steel during resistance spot welding: (i) downsloping current modif...
TL;DR: In this article, the particles and microstructure characteristics of coarse-grained heat-affected zone (CGHAZ) in Al-Ti-Mg killed steels with different Al contents were investigated.
Abstract: The particles and microstructure characteristics of coarse-grained heat-affected zone (CGHAZ) in Al–Ti–Mg killed steels with different Al contents were investigated. The results show that inclusion in high Al steel consists of Al–Mg oxide surrounded with a layer of MnS. However, inclusion in low Al steel is Al–Ti–Mg oxide covered with a layer of MnS, effectively promoting the formation of acicular ferrite. The precipitates of both steels are (Ti, Nb)N, the finer and more dispersed inclusions and precipitates in low Al steel can effectively inhibit austenite grain growth by grain boundary pinning during the thermal cycle. The fine-grained microstructure is obtained in CGHAZ of the low Al steel due to the pinning effect of finer particles and the high density of acicular ferrite.
TL;DR: Additive manufacturing of metallic materials and welding share many similarities in their physical processes and the way the microstructure and properties of the products evolve as discussed by the authors, which is called synergy.
Abstract: Additive manufacturing (AM) of metallic materials and welding share many similarities in their physical processes and the way the microstructure and properties of the products evolve. This synergy ...
TL;DR: In this paper, a multipass thick welded specimen restrained by three saddle-shape plates welded to the bottom surface was prepared and treated using the post-weld ultrasonic impact treatment (UIT).
Abstract: A multipass thick welded specimen restrained by three saddle-shape plates welded to the bottom surface was prepared and treated using the post-weld ultrasonic impact treatment (UIT). The stresses in the specimen were measured and analysed. Results show that the as-welded stresses on the top surface of the restrained specimen do not drop quickly beyond the weld zone as compared with the typical welding stress distributions in thick unrestrained specimens. The UIT induces compressive stresses with a depth up to 2–4 mm and it has little effect on the as-welded stresses outside of the UIT-treated region. The welding of restraining plates causes a significant increase of the longitudinal stress within the local welding region.
TL;DR: In this paper, the fatigue fracture mechanism of friction stir spot welding joint between aluminium alloy and carbon fiber reinforced plastic (CFRP) was investigated experimentally and analytically.
Abstract: One way of addressing environmental problems is to increase the use of light-weight materials in automobiles, such as the multi-material structure, which improves fuel economy and reduces pollution. However, it is necessary to develop a welding technique to join carbon fibre-reinforced plastic to metals to achieve a multi-material structure. So, this paper aims to shorten the welding time and to clarify the fatigue fracture mechanism of shear type friction stir spot welding joint between aluminium alloy and CFRP experimentally and analytically. As a result, the static and fatigue strength of the joint improved as the welding time increased due to the increase of total joint area to increased resin melting.