Journal of Advanced Joining Processes最新文献

Knowledge of the long-term performance of adhesive connections is undoubtedly of paramount importance to enable their deployment in civil, mechanical, and other engineering applications. Over time, adverse environmental conditions can strongly influence the performance of adhesive joints leading to a progressive deterioration of their initial mechanical properties. The use of adhesive connections for secondary structures in offshore applications is a technology that allows for the rapid creation of structural members that, however, cannot ignore the influence of hydrothermal effects on mechanical performance due to environmental conditions. In this context, the investigation of the hygrothermal durability of adhesive connections was undertaken through an extensive experimental programme. More specifically, 130 cylindrical steel joints bonded with a commercially epoxy resin for structural applications were tested in Mode I using an Arcan-modified device. Prior to test, the specimens were placed in climatic ovens capable of combining the effects of temperature and humidity for approximately 320 days. In addition, the glass transition temperature, T_g, was assessed by employing the differential scanning calorimeter (DSC) technique to correctly define the experimental ageing conditions. The experimental results show how ageing conditions influence the mechanical properties of the epoxy resin investigated. Finally, some predictive formulations are proposed to calculate the loss of strength of adhesive joints over time.

Due to the distinct physical and metallurgical characteristics of titanium and steel, the welding of these two materials poses challenges and holds significant importance. This study investigates the impact of brazing time and temperature on the microstructure and mechanical properties of dissimilar brazing between 17-4 PH stainless steel and Ti–6Al–4V using BNi-2 as a filler metal, focusing on the formation of brittle compounds like FeTi and Fe₂Ti during the brazing process. The joint between these materials is commonly utilized in various industrial applications. The assessment involved the use of optical microscope, scanning electron microscope, shear – tensile test, microhardness test, and wettability measurement. Brazing of the base metals was conducted at temperatures of 1050/1100 °C for durations of 15 and 30 min to determine the optimal temperature and time combination. The results indicated that the best joint properties were achieved at 110 °C for 15 min, with an average shear strength of 38.46 MPa. Contact angle measurements revealed that BNi-2 exhibited superior wettability on 17-4 PH compared to Ti–6Al–4V. Furthermore, increasing the temperature from 1050 to 1100 °C led to a reduction in contact angle from 9.98 to 8.83° for 17-4 PH, and from 16.51 to 10.12° for Ti–6Al–4V indicating an improvement in wettability.

The dissimilar welding of Inconel 718 (IN-718) alloy and AISI 410 martensitic stainless steel (MSS-410) is crucial in advanced gas turbines, and ultra-supercritical power plants to meet the demands of different operating conditions and lower the cost. However, the dissimilar fusion welding of IN-718/MSS-410 is challenging due to the differences in thermal expansion coefficient, physical and mechanical properties of base metals. In this study, the solid-state vacuum diffusion bonding (VDB) technology is employed to develop the dissimilar IN-718/MSS-410 joints. The aim of this study is to find the optimal combination of VDB parameters such as diffusion bonding pressure-DBP (MPa), diffusion bonding temperature-DBT (°C) and diffusion bonding time-DBt (min) for enhancing the strength of IN-718/MSS-410 joints. The response surface methodology (RSM) was integrated for designing the experimental matrix. The strength performance of VDB joints was evaluated by conducting the lap shear strength (LSS) and bonding strength (BS) tests. The mathematical LSS and BS predicting models were established using regression analysis and verified employing the variance analysis. The microstructural features were analyzed using optical and scanning electron microscopy (SEM). The X-ray diffractometer (XRD) was employed to identify the phases evolution in the joint interface. The experimental results revealed that the IN-718/MSS-410 joints diffusion bonded using the DBP of 14 MPa, DBT of 960 °C and DBt of 90 min exhibited the greater LSS of 280 MPa and BS of 373 MPa. The prediction models accurately predicted the LSS and BS of IN-718/MSS-410 joints within 2 % error at 95 % confidence. It is primarily concerned with developing the optimal bonding width with the fewest possible embrittlement implications and better joining interface coalescence. According to variance analysis, the DBt was the most significant parameter influencing the LSS and BS of joints followed by the DBP and DBT.

Dissimilar welding of Ti and Al alloys is challenging due to the potential formation of brittle intermetallics, which can compromise weld strength. Friction stir welding (FSW) is an advanced joining method with the potential to drastically reduce or prevent the formation of intermetallic phases because melting is avoided. However, in previous studies, dissimilar joints of Ti-6Al-4V and EN AW-7075 with satisfactory strength could not be achieved. Thus, we investigated friction stir welding of these two materials in a butt configuration, and analyzed the effects of post-weld heat treatments on the mechanical properties. Tensile strengths of 441 MPa in the as-welded condition and 505 MPa after heat treatment were achieved, significantly surpassing strength values reported in earlier studies. Microscopic investigations showed no evidence of formation of brittle intermetallic phases, and ductile fracture was observed. Our results show that FSW is a very promising candidate for future aerospace applications requiring dissimilar joining of Ti and Al alloys.

Due to the higher production cost of the monolithic carbide tools as well as their brittle nature, cemented carbides such as WC-Co are frequently joined to tool steel. To overcome the joining complications that arise due to notable differences in thermal expansions between the components and the poor wettability, various investigators have used copper-based and silver-based filler metals to dissimilarly braze the cemented carbides to steels. However, researchers do not agree about the selection of filler material. This research investigates the use of pure copper, brass, and silver-based filler metals to join the WC-Co cemented carbide to AISI 1045 steel. In this regard, microstructural features and mechanical properties including microhardness and shear strength were studied. The results indicate the formation of Cu(Fe,Co) solid solution and η carbides at the joint interfaces as well as the development of various precipitated phases in the joint area comprising Fe-Zn and Co-Zn intermetallic compounds. The reaction layers at both sides of the joints accompanied by cobalt-depleted zone on the hard metal side were observed. While using the $\alpha -\beta$ brass interlayer, the increase in hardness of the joint area through the presence of (Cu,Zn) solid solution compared to pure copper, the joint shear strength was enhanced from 161 to 173 MPa. On the other hand, the utilization of silver-based filler alloy with a distribution of hard copper-rich solid solution phase (182 HV) embedded in a silver-rich ductile matrix (88 HV), presenting a dispersion hardening effect, improved the shear strength of the joint to 203 MPa.

Investigation of the joining technology of 3D-printed parts into a large physical model has become an important research topic. Rotary friction welding (RFW) is one of the friction welding methods. Understanding the weld interface temperature changes in the weld center zone during RFW is critical because it is related to the weld quality of the welded parts using RFW. Traditionally, the number of revolutions is constant in the RFW. However, rare investigations focus on the fatigue specimen fabricated by RFW with variable rotational speed. This study used RFW with varying rotational speeds to fabricate fatigue specimens. The ANSYS software was used to predict the temperature history of rotary frictionally welded dissimilar polymer rods fabricated by a computer numerical control (CNC) turning machine with variable rotational speed. The RFW experiment of ABS/PC dissimilar polymer rods was conducted to investigate the temperature history and compared with the simulation results. It was found that the temperature history profiles were in good agreement with the experimental and simulation results. Compared with the weld interface heating rate obtained from the experimental results, the simulation results has average discrepancy rate about 4.48 %. Compared with the maximum temperature of the weld interface obtained from the experimental results, the simulation results has average discrepancy rate about 3.16 %. The fatigue life can be increased by approximately 1.4 times. Finally, a database of rotary frictionally welded dissimilar polymer rods fabricated by a CNC turning machine with variable rotational speed was proposed. The average Shore A surface hardness at the weld interface was enhanced by approximately 18 % compared to the base ABS material.

Material Extrusion (MEX) 3D printing is revolutionizing manufacturing by transforming digital designs into tangible innovations by its layer-by-layer approach. However, an important issue impeding the adoption of this technology is the limited size of the prints due to the machine's small bed. An appropriate polymer joining technique can be used as a post-fabrication step to circumvent this issue. This paper explores the findings related to the joining of MEX-3D printed parts fabricated from generally preferred thermoplastics, Acrylonitrile Butadiene Styrene (ABS), and Polylactic acid (PLA) by the Spin Friction Welding (SFW) technique. The critical parameters involved in the process are identified and optimized using statistical tools including Design of Experiments (DOE), Taguchi, and Analysis of Variance (ANOVA). The results revealed that the type of material combination as well as the number of perimeter shells had the highest effect on the joint strength and cylindricity of the welds, resulting in the joint efficiency going up to 93.16 %. The practicability of the research was further approved by implementing the results to weld the sections of a service saddle point of a pipeline, wherein the weld displayed good strength and integrity. With the suggested method, it is expected that in the future, joining and welding procedures will gain more acceptance with SFW in particular showing great promise for joining cylindrical and rotary MEX-3D printed parts.

The combination of additively manufactured metal components with thermoset fibre-reinforced composites provides the possibility to produce hybrid structures with increased functionality and reduced mass. The application in the high-performance sector, for example the implementation of such a hybrid structure in electric drive units in aviation, provides the potential to achieve the high power densities required. The challenges in this regard are the manufacturing, design and dimensioning of the interface between the two components regarding the technical requirements, such as the high temperature range. In this publication, metal specimens are manufactured using selective laser melting (SLM) and then pre-treated. The joint with the composite is obtained in the subsequent infiltration process when the composite part is manufactured. For the experimental characterization of the interface different combinations of fibre-reinforced composites and metals are used. Within roughness measurement the surface of the different materials due to the treatment were analysed and the intrinsic interfaces were microscopically examined. The joint strength is investigated in double lap shear test at different temperatures and the results are discussed based on the fabrication process and the characteristics of the hybrid interface. The results provide the basis for the future design and numerical description of the interfaces.

Some aluminum alloys, such as those alloyed with Si and Mg, are difficult to weld due to their susceptibility to hot cracking. Previous research has investigated this challenge in resistance spot welding (RSW). To improve the weldability of the AW-6111 aluminum alloy, the roll cladding process was employed, combining it with AW-4045 as the cladding material. This resulted in a wider weld lobe, improved electrode wear, and enhanced joint quality. However, it is evident that the cladded material could benefit from improved welding conditions. Despite a larger nugget diameter, similar mechanical properties were observed for both the minimum and maximum boundary conditions of the weld lobe, determined by I_nom and I_max.

This study employed a design of experiments approach to optimize the joint strength and improve the weld quality of the AW-6111 + AW-4045 cladded sheets. The tensile-shear test results demonstrated an improvement in lap-shear strength of 38 % and 44 % compared with the previous study. Furthermore, the test samples predominantly exhibited a ductile partial thickness failure mode, and a significant improvement in the weld nugget quality of the cladded AW-6111 + AW-4045 was observed. The cladded joints also exhibited a Si alloying content of approximately 5 % in the heat-affected zone and fusion zone, thereby reducing the risk of crack formation and propagation, thus improving significantly the weld quality. The results of this study contribute with the continuous validation of Al alloys for the transport industry and with the use of cladding technology to enhance the aluminum sheet properties and respective weld quality.

The present work deals with the effect of penetration depth on welding T-joints through conventional friction stir welding (FSW) as well as underwater friction stir welding (UFSW). Various set of parameters have been used such as tool rotational speeds of 1000, 1400, and 1800 rpm, and depths of penetration, such as 6, 7, and 8 mm. In UFSW, lower heat generation prevents the development of complex intermetallic compounds and defects in welding. Additionally, in the weld region, a rapid cooling rate in UFSW generates fine microstructural particles. Mechanical and microstructural characteristics has been compared in both UFSW and FSW. There was a substantial grain size effect on mechanical properties. The stir zone shows comparatively finer grains with average grain size of 49.76 µm at 1800 rpm and 7 mm depth of penetration. It was seen that the tensile strength of UFSW was 189.9 MPa and the nugget zone hardness was 70 VHN, compared to the FSW that has 175.2 MPa and 62 VHN, respectively, obtained at a rotation speed of 1800 rpm and a travel speed of 60 mm/min. The joints tested at various penetration depths show a significant number of uniform and equiaxed dimples. The presence of ductile rupture and the formation of dimples suggest that the joints were effectively bonded and tested at different strain rates.