THE INFLUENCE OF FRICTION STIR WELDED PROCESS PARAMETERS OF AA2519-T62 ON JOINT QUALITY DEFINED BY NON-DESTRUCTIVE LASER AMPLIFIED ULTRASONIC METHOD AND BY MICROSTRUCTURE ANALYSIS

The presented research contains a description of a non-destructive laser ultrasound internal structure analysis of aluminium joints made by friction stir welding. In the research, four selected technological parameter groups were taken into account. Modifications used in different parameter groups included changing tool traverse speeds and also its rotation speeds. The most important goal of this research was to determine the joint quality using a non-destructive laser amplified ultrasound method  To verify obtained test results, an additional microstructural analysis was also conducted

Properties of welded joints made in high strength steel using laser technology

The usage of high strength steels (HSS) provides numerous benefits in the form of the cross- section area reduction causing weight decrease, improvement in exploitation parameters and in result positive financial effect. The most advantageous results are observed in the parts loaded by tensile stresses. The factors most influencing the fatigue strength of the metals, especially the steels of high value of yield point, are stress concentration in the originated geometrical notches, local changes of the stress state or the microstructure of paternal material. Improvement in the fatigue behaviour of HSS steels can be achieved by changing the commonly used technique for high-energy joining technology, namely laser beam welding. Relatively narrow welds and reduced heat-affected zone (HAZ) have minimized the residual stresses and distortions. The paper presents the results of the studies focused on mechanical properties of welded joints of high strength fine-grained steel S960QL. There was investigated the impact of heat input on the microstructure, microhardness- and residual stresses in the weld and HAZ. The crucial part is devoted to the fatigue research and fractographic investigation of the fatigue ruptures of laser-made welds. There were also found in the origins the cause of crack initiation. Keywords: mechanics, fatigue life, high strength steel, laser weldin

Metal Additive Manufacturing (MAM) Applications in Production of Vehicle Parts and Components—A Review

In this article, the significance of additive manufacturing techniques in the production of vehicle parts over the past several years is highlighted. It indicates the industries and scientific sectors in which these production techniques have been applied. The primary manufacturing methods are presented based on the materials used, including both metals and non-metals. The authors place their primary focus on additive manufacturing techniques employing metals and their alloys. Within this context, they categorize these methods into three main groups: L-PBF (laser-powder bed fusion), sheet lamination, and DED (directed energy deposition) techniques. In the subsequent stages of work on this article, specific examples of vehicle components produced using metal additive manufacturing (MAM) methods are mentioned

Mechanical Properties Analysis of Explosive Welded Sheet of AA2519-Ti6Al4V with Interlayer of AA1050 Subjected to Heat-Treatment

The paper presents results of investigations of welding sheets of AA2519-Ti6Al4V, a difficult-to-joint components materials, produced by explosive welding with a thin technological interlayer of AA1050. The joining process leads to the formation of intermetalics in the vicinity of joint and generates significant residual stresses. In the next step the laminate was subjected to a heat treatment process in order to improve the mechanical properties by precipitation hardening. This treatment should not be carried out before welding because of negative influence on a ductility of the aluminum alloy. Material in this state was subjected to the tests of chemical composition, microstructure, and microhardness. A tensile test was carried out with accompanying strain analysis by the digital image correlation (DIC) method. Moreover, the residual stresses were determined which were measured by using two methods, the X-ray diffraction and the hole drilling. This approach made it possible to measure the residual stresses both in the plane parallel to the surface and in the cross section of the laminate

Research on the Friction Stir Welding of Sc-Modified AA2519 Extrusion

The aim of this research was to investigate the effect of friction stir welding (FSW) parameters on microstructure and mechanical properties of Sc-modified AA2519 extrusion joints. The workpiece was welded by FSW in non-heat-treated condition with seven different sets of welding parameters. For each obtained joint macrostructure and microstructure observations were performed. Mechanical properties of joints were investigated using tensile test together with localization of fracture location. Joint efficiencies were established by comparing measured joints tensile strength to the value for base material. The obtained results show that investigated FSW joints of Sc-modified AA2519 in the non-heat-treated condition have joint efficiency within the range 87–95%. In the joints obtained with the lowest ratio of the tool rotation speed to the tool traverse speed, the occurrence of imperfections (voids) localized in the stir zone was reported. Three selected samples were subjected to further investigations consisting microhardness distribution and scanning electron microscopy fractography analysis. As the result of dynamic recrystallization, the microhardness of the base material value of 86 HV0.1 increased to about 110–125 HV0.1 in the stir zone depending on the used welding parameters. Due to lack of the strengthening phase and low strain hardening of used alloy the lack of a significantly softened zone was reported by both microhardness analysis and investigation of the fractured samples

The Influence of Exposure Energy Density on Porosity and Microhardness of the SLM Additive Manufactured Elements

Selective laser melting (SLM) is an additive manufacturing technique. It allows elements with very complex geometry to be produced using metallic powders. A geometry of manufacturing elements is based only on 3D computer-aided design (CAD) data. The metal powder is melted selectively layer by layer using an ytterbium laser. This paper contains the results of porosity and microhardness analysis made on specimens manufactured during a specially prepared process. Final analysis helped to discover connections between changing hatching distance, exposure speed and porosity. There were no significant differences in microhardness and porosity measurement results in the planes perpendicular and parallel to the machine building platform surface

Effect of Welding Parameters on Mechanical Properties and Microstructure of Friction Stir Welded AA7075-T651 Aluminum Alloy Butt Joints

The aim of this study was to examine the mechanical properties of 5-mm-thick AA7075-T651 alloy using three different welding velocities, 50, 75 and 100 mm/min, and four various sets of tool rotation speeds: 400, 600, 800 and 1000 rpm. All obtained joints were defect-free. In all cases, the values of UTS exceeded 400 MPa, corresponding to 68.5% minimum joint efficiency. The highest value of 447.7 MPa (76.7% joint efficiency) was reported for the joint produced via 400 rpm tool rotation speed and 100 mm/min welding velocity. The SZ microstructure of the strongest joint was characterized by a 5.2 ± 1.7 μm grain size and microhardness of approximately 145 HV0.1. The TMAZ/HAZ interface was identified as the low-hardness zone (105–115 HV0.1, depending on parameters), where the failure of the tensile samples takes place. The fracture mechanism is dominated by a transgranular ductile rupture with microvoid coalescence

The Influence of Post-Weld Heat Treatment on the Microstructure and Fatigue Properties of Sc-Modified AA2519 Friction Stir-Welded Joint

The aim of this research was to investigate the influence of post-weld heat treatment (PWHT, precipitation hardening) on the microstructure and fatigue properties of an AA2519 joint obtained in a friction stir-welding process. The welding process was performed with three sets of parameters. One part of the obtained joints was investigated in the as-welded state and the second part of joints was subjected to the post-weld heat treatment (precipitation hardening) and then investigated. In order to establish the influence of the heat treatment on the microstructure of obtained joints both light and scanning electron microscopy observations were performed. Additionally, microhardness analysis for each sample was carried out. Fatigue properties of the samples in the as-welded state and the samples after post-weld heat treatment were established in a low-cycle fatigue test with constant true strain amplitude equal to ε = 0.25% and cycle asymmetry coefficient R = 0.1. Hysteresis loops together with changes of stress and plastic strain versus number of cycles are presented in this paper. The fatigue fracture in tested samples was analyzed with the use of scanning electron microscope. Our results show that post-weld heat treatment of AA2519 friction stir-welded joints significantly decreases their fatigue life

Research on the Microstructure of Laser Beam Welded Sc-Modified AA2519-F Extrusion

In this paper, the microstructure of laser beam welded Sc-modified AA2519-F has been taken under investigation. The welded joint has been produced using Fanuc 710i industrial robot equipped with YLS-6000 6 kW laser beam source. The welding speed and laser power were equal to 0.75 m/min and 3.2 kW, respectively. The investigation involved microstructure observations with the use of both light microscope and scanning electron microscope with energy dispersive spectroscopy (EDS) analysis of chemical composition and microhardness distribution measurements. It has been stated that laser beam welding allows to obtain Sc-modified AA2519-F weld of good quality, characterized by the presence of an equiaxed grain zone containing scandium-rich precipitates adjacent to the fusion boundary

The influence of welding parameters on macrostructure and mechanical properties of Sc-modified AA2519-T62 FSW joints

In this investigation, a 5 mm thick extrusion of AA2519-T62 alloy has been welded using friction stir welding method. The various sets of process parameters have been involved within the range of 400–1200 rpm tool rotation speed and 100–800 mm/min welding speed. Selected joints have been subjected to the macrostructure analysis, microhardness measurements, tensile and low cycle fatigue testing (at ε = 0.3%), and fractography analysis. It has been stated that imperfection-free macrostructure is obtained for welds produced with lowest welding speed: 100 mm/min and tool rotation speed within the range of 400–800 rpm. The highest joint efficiency (85%) has been obtained for the sample characterized by the presence of voids in the upper part of the stir zone. Considering macrostructure analysis and established mechanical properties of the joints, it may be concluded that the best set of welding parameters for AA2519-T62 is within the range of 600–800 rpm tool rotation speed with welding speed of 100 mm/min for used MX Triflute tool