Papers by Keyword: Butt Joint

Abstract: This paper investigates residual stresses of the laser welded abrasion resistant steel butt joints. X-ray diffraction (XRD) was used to measure the residual stresses of the laser welded joints. The geometry and mechanical properties of the joints were also investigated. The weld metal hardness of the weld made with the lowest welding energy corresponded to the hardness of the base material. The welding energy had a significant effect on the hardness profiles of the welds. With the lowest welding energy, the tensile strength reached a strength corresponding to the yield strength of the base material. The residual stress results perpendicular to the weld corresponded well to the hardness profiles of the joints. The residual stresses were mainly tensile stress. The measured maximum residual stresses were 480 MPa.

Abstract: We report on an analytical model for damage description in adhesive butt joints. In themodel, the thin adhesive layer is replaced by a damaging bonding interface. The mechanical behaviorof the interface is described by a nonlinear and rate­dependent imperfect contact law. The law takesinto account both stress and displacement jumps, and it can describe both soft and hard adhesive layers.Unlike classic cohesive zone models, phenomenological in nature, the proposed contact law explicitlyaccounts for material and damage properties of the adhesive layer. A first comparison with literaturedata of adhesive butt joints loaded in torsion indicates that the model can successfully reproduce theirexperimental stress­strain response.

Abstract: The present study is focused on joining two ultra-high strength steels plates of 3 mm thickness using laser-welding. Abrasion resistant steel with martensitic structure, tensile strength (R_m) ≥ 2 GPa, and cold-deformed austenitic stainless steel, R_m 1.3 GPa, were used for the dissimilar butt joints. Two different laser energy inputs, 160 and 320 J/mm, were presented during welding. The weld morphology and microstructural evolution of the fusion zone were recorded using optical microscopy and electron back scattering diffraction (EBSD), respectively. The mechanical properties of the dissimilar joints were evaluated by hardness measurements and tensile tests. It was found that fusion zone has undergone a change in morphology and microstructure during welding depending upon the energy input. Analysis of the microstructural evolution in the fusion zone by EBSD examination showed that the presence of a mixture of small austenite grains in a matrix of martensite. The changes in hardness profiles and tensile strength under the experimental parameters were further reported.

Abstract: The joining of similar and dissimilar AA2014, AA6068 and AA7075 aluminium plates of 6mm thickness was carried out by friction stir welding (FSW) technique. FSW of Aluminium to Aluminium has caught significant consideration from assembling industries, such as Shipbuilding, Automotive, Railway and Aircraft generation. Here, the chosen process parameters are tilt angle (2º), tool rotation speed (900rpm) and transverse feed of (80mm/min) at constant axial force 2kN. An attempt was made to join the similar and dissimilar aluminium plate of 6 mm thickness with a conical tapered tool profile. Then, the effect of welding speed on microstructures, hardness distribution and tensile properties of the welded similar and dissimilar joints AA2014, AA6068 and AA7075 were investigated.

Abstract: This Paper presents the study on the weldability of two similar and two different metallic materials. The weldability of the similar metallic materials considered in the study were aluminum alloy pipes of grade AA6063. As for the weldability of two different metallic materials were aluminum alloy of grade AA6061 to low carbon steel of grade A36, dupl stainless steel of grade 2205 to low carbon steel of grade A36 and grey cast iron of grade A48 class 35 to low carbon steel BS 449 of grade 250. The differing methods of welding or joining processes are discussed herein including those of stir welding and hot pressed diffusion bonding of the similar and dissimilar metallic materials respectively as mentioned above. The weldability of between the two materials are investigated including the physical appearance of the joints and the strength integrity of those so far achieved at this stage. The paper also presented the results on the weldability of the similar and different metallic materials, recommendation for further in-depth study in pursuit for improved technologies on the subject matters and highlight the prospects of metallic materials welding or bonding or joining to fulfill the demands for different applications.

Abstract: This research work aimed to study an effect of interpass temperature on a wear resistance of a hard-faced weld metal on JIS-S50C carbon steel surface. The experimental results were found that the increase of the interpass temperature resulted in the increase of the grain size, the decrease of the hardness, and the decrease of wear resistance of the hard-face weld metal. Low interpass temperature affected to increase the residual stress inducing the cracking on the interface between the first weld metal layer and the base metal. Wear surface composed the crater and the groove wear traces that showed the different evidence of the failed off metal particles. The lower wear rate was found at the location where contained high amount of the reinforced elements such as chromium, silicon and manganese. The lowest weight loss of 0.89% could be obtained with an application of the optimum interpass temperature of 150 °C.

Abstract: An optimization of a gas metal arc welding (GMAW) process parameter is currently investigated for producing a dissimilar SS400/SUS304 steels joint because a requirement of a sound joint with higher tensile strength. A gas shielding type is one of the important parameter because it could produce a good arc, protect the weld pool from atmosphere and so on. So, this research work aimed to study an effect of the shielding gas type on the mechanical properties of the dissimilar SS400/SUS304 steels butt joint. A relation between microstructure and the mechanical properties of the butt joint was also investigated and compared. The summarized results are as follows. The optimized shielding gas that produced a maximum tensile stregnth of 550 MPa was 95%Ar+5%N₂. Nitrogen gas that mixed to the shielding gas affected to decrease dendrite size and to increase the hardness and tensile strength of weld metal. Fracture characteristic of the joint produced by N₂ mixed gas showed a larger deformation at the location that was closely the fracture location that implied a ductile behavior. The dissimilar SUS304/SS400 metals joint showed a low hardness base metal, a higher hardness interface and a highest hardness weld metal.

Abstract: This paper focused on applying friction stir weld method on welding a butt joint of wrought6063-T1 aluminum alloy and cast Mg-Si aluminum alloy and studied on effect of various parameterssuch as rotating speeds and travelling speeds. The experiment revealed that a variation of the rotatingand travelling speeds affected to vary the weld quality. Higher rotating speed and higher travellingspeed produced the defects such as voids that directly decreased tensile strength of the joint. Whenthe sound weld metal with the high tensile strength was produced, the failure of the tensile testspecimen was located at the cast aluminum alloy. The average tensile strength of the sound joints was10-15% higher than that of the cast aluminum alloy. Microstructure investigation of the specimenwith the optimum welding parameter revealed that the combination of the aluminum alloys wascompleted without any defect in the weld metal. Compressed force by the welding tool produced thesmall compacted grain in the weld metal and small combined banding area at the interface of boththe cast aluminum alloy and the weld metal.

Abstract: High nitrogen austenitic steels are used as structural materials required possessing high strength and fracture toughness. The present study is concerned with the characteristic features (shape, size, properties and structure) of the laser welded joints in Cr-Mn-, Cr-Mn-Mo-high nitrogen steels compared to the ones of Cr-Ni-steel joint. Butt welded joints were made using carbon dioxide laser with a maximum output of 5 kW in the continuous wave mode. The hardness and tensile tests of welded joints in the air and 3.5 vol.%-solution of NaCl, as well as the theoretical studies were carried out by optical and transmission electron microscopy (TEM). The results are achieved by testing that the welded joints of HNS had satisfactory weldability, adequately high mechanical and corrosion properties. The austenite of the investigated HNS retains high stability throughout the welding cycle.

Abstract: The present work investigates the effects of laser beam power, focus position and advance speed on the geometry, microstructure and mechanical properties of fiber laser beam welded Ti-6Al-2Sn-4Zr-2Mo (denoted as Ti-6242) butt joints used for high temperature applications. Detailed microstructural and mechanical studies were performed on welds produced using optimized parameters (a laser beam power of 5 kW, a focus position of 0.0 mm and an advance speed of 6.2 m/min). The Ti-6242 base material is characterized by a globular (α+β) microstructure. The heat input during laser beam welding led to the formation of a martensitic α’-phase fusion zone. The heat affected zone consisted of globular grains and acicular crystallites. These local transformations were connected with a change in the micro-texture, average grain size and β-phase content. Furthermore, the microhardness increased from 330 HV 0.3 to 450 HV 0.3 due to the martensitic transformation. The mechanical behavior of the laser beam welded Ti-6242 butt joint loaded in tension was determined by the properties of the Ti-6242 base material. The local increase in hardness provided a shielding effect that protected the Ti-6242 butt joint against mechanical damage.