Machine learning (ML) methods have received immense attention as potential models for modeling different manufacturing systems. This paper presents a comprehensive review on the applications of ML ...methods in friction stir welding (FSW) field. Five main topics have been discussed: prediction of the joint properties, integration between ML and finite element methods, real-time control of FSW process, tool failure diagnosis, and incorporation between metaheuristic optimization techniques and ML methods. The common used ML methods such as multi-linear regression, K-nearest neighbor, random forest algorithm, Gaussian process regression, artificial neural network, support vector machine, radial basis function neural network, fuzzy system, adaptive neuro-fuzzy inference system, and random vector functional link are explained. Then, different statistical measures used to evaluate the performance of ML methods are presented. Finally, the applications of ML methods in FSW field are discussed. Important conclusions are drawn and future prospects are suggested.
This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, ...Ti6Al4V titanium alloy plates with a thickness of 0.8mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.
This paper examines dissimilar friction welding between electrolytic tough pitch copper (ETP-Cu) and stainless steel (SS) of grade 304 L for pipe joint configuration, having 0.06 wall thickness to ...pipe diameter ratio. The welding is performed using the continuous drive friction welding method. The welded joint is evaluated by visual inspection, leak-proof ability by helium leak detection testing, microstructure features by optical and scanning electron microscopy, energy dispersive x-ray spectroscope, x-ray diffraction patterns, tensile testing, and hardness measurements. The continuity of welding is evaluated by peripheral inspection and testing on four different locations of pipe welded joint. The results revealed that sound joints between dissimilar materials of Cu-SS are established with evidence of resistance to leak at room temperature and after cryogenic shock test. The Cu-SS pipe joint received excellent strength of 242.48 N/mm2, which is nearly 80% of ETP-Cu base material. The microstructure changes are distinctly observed at the Cu side, whereas no significant microstructure changes are observed at the SS side. The microstructure features are consisting of full dynamic recrystallization zone and partial dynamic recrystallization zone that are identified at the Cu side. However, no adverse effect of microstructure on tensile strength and hardness is observed. The weld continuity in the periphery of pipe configuration is observed at four different locations. A continuous reaction layer at four investigated locations is identified, with the presence of Cu and Fe elements at the joint interface.
A novel ultrasonic vibration enhanced friction stir welding (UVeFSW) was employed to join the third- generation 2195-T6 Al−Li alloy, and the effect of ultrasonic vibration on microstructures and ...mechanical properties of the joint was studied. It is revealed that UVeFSW can enhance the plastic material flow to suppress the weld defects. The critical welding speed of sound joints is increased in UVeFSW compared with conventional FSW. When ensuring that the tensile strength of the joint is 75% that of the base material, the welding speed and efficiency in UVeFSW are higher than those in conventional FSW. Superimposing ultrasonic vibration can significantly enhance the mechanical properties of 2195 Al−Li alloy FSW joints at a higher welding speed. The maximum tensile strength of the UVeFSW joint is 449.5 MPa, which is 83.1% that of the base material. UVeFSW can increase the welding efficiency by increasing the critical welding speed and simultaneously ensuring the joint properties.
High entropy alloys (HEAs) emerged in the beginning of XXI century as novel materials to "keep-an-eye-on". In fact, nowadays, 16 years after they were first mentioned, a lot of research has been done ...regarding the properties, microstructure, and production techniques for the HEAs. Moreover, outstanding properties and possibilities have been reported for such alloys. However, a way of jointing these materials should be considered in order to make such materials suitable for engineering applications. Welding is one of the most common ways of jointing materials for engineering applications. Nevertheless, few studies concerns on efforts of welding HEAs. Therefore, it is mandatory to increase the investigation regarding the weldability of HEAs. This work aims to present a short review about what have been done in recent years, and what are the most common welding techniques that are used for HEAs. It also explores what are the measured properties of welded HEAs as well as what are the main challenges that researchers have been facing. Finally, it gives a future perspective for this research field.
The purpose of this study was to develop a high-efficiency and low-heat-input CO2 arc-welding process using hot-wire feeding. A previous paper showed that the proposed hot-wire CO2 arc-welding ...process has the potential to simultaneously achieve both high efficiency and low heat input. This paper investigated the production of a sound joint with only two welding passes on a butt joint of 20mm-thick steel plates with no defects or unstable welding phenomena using the developed hot-wire CO2 arc-welding process. Welding condition optimization was investigated using high-speed imaging and cross-sectional observations. The optimized conditions, which were the combinations of the welding current and hot-wire feeding speed as 350A and 7.5m/min, 400A and 5m/min, 450A and 5m/min, 500A and 5m/min, derived to avoid the presence of defects and molten metal precedence, which achieved sound welded joints possessing adequate properties of strength and toughness.
In this work, Zr-Sn-Nb alloy was joined by electron beam welding (EBW). A defect-free Zr-Sn-Nb joint with sound appearance was obtained. The grains in the weld zone (WZ) and heat-affected zone (HAZ) ...are significantly coarsened. The columnar grains with a maximum grain size of 0.5 mm are distributed in the upper region of the WZ, while the equiaxed grains are almost located in the bottom region of the WZ. The WZ is mainly composed of the dominant α-Zr, α'-Zr and a few β phases. The grain orientation of WZ and HAZ is uniform, indicating that no obvious preferred orientation existed. Coarse grains and fine acicular α' phases increase the strength of the joint, but reduce the plasticity and toughness of the joint. The tensile strengths of the joints at room temperature (RT) and 375 °C were 438 MPa and 313 MPa, respectively. The RT impact energy of the joint is 18.5 J, which is only 58.3% of the BM. The high purity of the EBW process and unsignificant grain orientation minimizes damage to the corrosion resistance of Zr-Sn-Nb alloy joints. The corrosion weight gain of the joint specimen and the BM specimen were 12.91 mg/dm
and 12.64 mg/dm
, respectively, and the thicknesses of the cross-section corrosion layer were 12-15 μm and 9-12 μm, respectively.
In this paper, a metal inert gas (MIG) shielded welding method was used for high-quality welding of 6063-T6 aluminum alloy sheet with a thickness of 2.5 mm. The welding process of MIG welding was ...accurately simulated and the welding temperature field and thermal cycle curve were calculated using a combination of Gaussian body heat source and double ellipsoidal heat source. As the welding current increased from 75 A to 90 A, the reinforcing phase precipitated under the microstructure of the joint gradually became larger and re-solidified into the body, resulting in a reduction in mechanical properties. When the welding current is 85 A, the pitting resistance of weld forming and weld area reaches its optimum. At this time, the tensile strength of the joint is up to 110.9 MPa, the elongation is up to 16.3% and the Vickers Microhardness is up to 46.9 HV.
Demand for structural glazing joints has increased considerably in recent years due to the ever-increasing loads resulting from growing dimensions, especially in spectacular glass structures. Within ...the scope of planning and production monitoring, existing influences are analyzed based on the standard H-sample from the current structural glazing guidelines. These guidelines do not define any specific methodology or guidance for manufacturing test specimens. For determining load-bearing properties, various parameters, such as specimen age and curing condition, have a relevant influence during and after manufacturing. This study aims to investigate the manufacturing process for H-specimens systematically to identify and minimize the interfering influences. On this basis, the influence of the curing of modified H-specimens was investigated in detail for specimens under tensile load. Next to curing at room temperature, tempering at 40 °C was investigated for two different H-joint geometries. Thereby, a relevant influence of specimen age and different curing conditions on the strength as well as stiffness properties could be determined. As one result of the study, the curing time can be shortened by tempering the specimens in relation to the specified 28 days by ETAG 002-1. For calculation methods used in practice, like the structural spring method, suggestions for statistically validated strength and stiffness parameters representing the load-bearing behavior are proposed, considering the adhesive’s curing state and the joint’s nominal stress.
PDF
