In this study, CNTs were uniformly decorated with nanosized Ni via a microwave-assisted electroless plating method. Using these Ni-CNTs as reinforcements, nano-WC-CoCr/Ni-CNTs powders were fabricated. Subsequently, coatings were deposited by high-velocity air-fuel (HVAF) process. The addition of an appropriate amount of Ni-CNTs contributes to superior microstructure, mechanical properties, and wear resistance of WCCoCr/Ni-CNTs coating. When Ni-CNTs addition was 1.30 wt%, Ni-CNTs were uniformly dispersed, resulting in a coating characterized by low porosity and minimal decarburization. The WC phase content exceeded 98 wt% as determined by XRD quantitative phase analysis. This specific coating maintained a relatively higher microhardness while achieving a 19% improvement in fracture toughness (7.42 MPa center dot m1/2) compared to nano-WC10Co4Cr coating. The enhancement in mechanical properties is primarily attributed to following factors: improved dispersion homogeneity of CNTs; enhanced interfacial wettability between CNTs and WC, CoCr binder facilitated by Ni; the establishment of strong metallurgical bonding among the Ni-CNTs, WC, and CoCr binder; and bridging effect of Ni-CNTs. Furthermore, the wear resistance was enhanced, exhibiting a steady-state friction coefficient of 0.585 and a volumetric wear rate of 3.67 & times; 10-6 mm3 center dot N- 1 center dot m- 1(decreased by 14%). The dominant wear mechanism was oxidative wear. The formation of oxidised patches rich in W and Co provided lubricating effects, thereby contributing to decreased wear rate. The applicability of this process extends beyond the scope of this work, providing a practical approach for developing CNTs reinforced WC-based spray powders.

This study proposes a novel high-frequency impact electrospark treatment (HFIET) method to fabricate Al/AlN composite layers on 2024-T3 aluminum alloy substrates. The HFIET process utilized nitrogen as both the shielding gas and reactive nitrogen source for in situ synthesis of AlN, with precisely controlled discharge parameters to minimize substrate thermal damage. Analysis revealed a dense Al/AlN composite layer with near-stoichiometric composition (Al:N atomic ratio approximate to 1:1), confirmed by EDS and XRD. The microhardness profile exhibited a gradient distribution, decreasing from 450 HV at the surface to the substrate hardness (similar to 120 HV), attributed to the gradual reduction in AlN volume fraction from the top layer to the interior. Tensile tests demonstrated simultaneous improvements in ultimate tensile strength (similar to 10 % increase) and elongation (similar to 30 % increase) compared to untreated 2024-T3 alloy, indicating enhanced strength-ductility synergy. Corrosion resistance was significantly enhanced, and the Al/AlN layer acts as an effective barrier against corrosive media infiltration, suppressing pitting initiation at the coating-substrate interface.

A novel carbon nanotubes-metal-ceramic nanocomposite powders was synthesized, and dense coatings were subsequently fabricated to investigate their microstructure and mechanical properties. Through chemical vapor deposition (CVD), carbon nanotubes (CNTs) were in-situ grown within nano-sized WC-CoCr powders, achieving uniform dispersion of CNTs throughout the matrix. High-velocity air fuel (HVAF) spraying was employed to fabricate dense CNT-reinforced WC-CoCr coatings with minimized decarburization while preserving the structural integrity during the thermal spraying process. The incorporation of 0.3 wt% CNTs led to simultaneous enhancement in both hardness and fracture toughness. Compared to the CNTs-free coating, the CNTs-reinforced coating exhibited a 4.58 % and 17.90 % increase in hardness under 100 g and 300 g loads, respectively, along with a significant 49.59 % improvement in fracture toughness. The significant mechanical improvements are primarily attributed to the existence of strong metallurgical bonding between the CNTs and both the WC and the CoCr binder phase, coupled with the formation of Y-junction CNTs.

Oscillating laser welding (OLW) of aluminum alloys has attracted increasing attention due to its reduced temperature gradients, low porosity, and high tolerance to joint gaps, making it particularly suitable for applications in the transportation and aerospace industries. Penetration depth is a key indicator governing weld integrity and heat input efficiency. However, most existing OLW studies focus primarily on reporting penetration depth variations, while anomalous behaviors and the associated thermal–fluid mechanisms remain insufficiently understood. To address this gap, a numerical thermo-fluid model for OLW is developed in the present work. Particular emphasis is placed on elucidating how oscillation-induced complex melt flow affects energy dissipation and heat transfer within the molten pool, thereby providing a mechanistic explanation for the anomalous penetration depth observed in OLW. The non-monotonic dependence of penetration depth on oscillation frequency and oscillation radius is primarily attributed to two factors. First, distinct flow regimes are formed under different oscillation conditions, ranging from laminar flow dominated by a single preferential direction at large oscillation radii to strongly turbulent flow with multiple vortical structures at high oscillation frequencies. Second, larger oscillation radii intensify melt surface fluctuations, inducing pronounced “hydraulic jump” phenomena that enhance kinetic energy dissipation within the molten pool. In particular, the anomalous increase in penetration depth at high oscillation frequencies is governed by the interaction between competing melt flow structures. At an oscillation frequency of 800 Hz, the central vortex undergoes a sequence of expansion, contraction, and stabilization, while the laminar flow near the bottom of the molten pool experiences expansion, compression, disappearance, and reappearance. The dynamic competition between these flow patterns expands the turbulent region at the bottom of the molten pool and modifies the thermal boundary characteristics. This transition from a transitional boundary layer to a smoother and more stable interface significantly enhances heat transfer between the melt flow and the bottom boundary. Consequently, an efficient energy transfer pathway is established among the laser source, molten pool, and base material, resulting in a deeper penetration depth.

Molten calcium-magnesium-alumino-silicate (CMAS) corrosion is a primary failure mode of thermal barrier coatings (TBCs) during service. To enhance the CMAS resistance of conventional atmospheric plasma sprayed (APS) yttria-stabilized zirconia (YSZ) coatings, this study employed thin-walled hollow spherical (THS) YSZ powder to fabricate TBCs. Owing to its superior melting characteristics, a dense and uniform coating structure containing noninterconnected pores was successfully obtained. The degradation behavior of APS TBCs prepared from three powder types-THS, conventional sintered-crushed (SC), and nanoagglomerated (NA), differing in morphology and grain sizes-was systematically compared after CMAS corrosion at 1240 degrees C for 0.5, 8, and 16 h. The results indicate that the THS-YSZ coating exhibited the most superior resistance to CMAS corrosion, with a continuous corrosion depth of only about 6 & micro;m after 16 h. In contrast, the SC-YSZ coating underwent severe degradation with extensive spallation and disintegration, reaching a maximum corrosion depth of 81 & micro;m, while the NA-YSZ coating also suffered significant corrosion with a penetration depth of 37 & micro;m. This work demonstrates that tailoring the coating microstructure through powder design represents an effective strategy to enhance the CMAS resistance of APS-YSZ coatings.

Laser glazing has been explored to seal surface defects in thermal barrier coatings (TBCs) and enhance their hightemperature performance under aggressive environments. However, a critical limitation of conventional laser glazing is the unavoidable formation of cracks within the glazed layer, which undermine its effectiveness. This study proposes a laser glazing technique using a nanosecond-pulsed ultraviolet KrF excimer laser. This technique enables the formation of a unique dual-layer surface structure, characterised by a nanoparticle deposition layer atop a glazed layer, achieving effective sealing of surface defects in plasma-sprayed yttria-stabilized zirconia (YSZ) coatings without inducing cracks. Morphological analysis shows the coating surface evolves distinctively with increasing laser fluence: from a densely solidified structure via melting at lower fluences to a solidified layer covered by re-deposited nanoparticles at higher fluences. Benefiting from the dual-layer structure's synergistic effects, the glazed coatings exhibit significantly enhanced resistance to various degradation mechanisms. Compared to as-sprayed coatings, they show a 41.4 % reduction in t'-ZrO2-to-m-ZrO2 phase transformation after CMAS corrosion, a 36.2 % decrease in thermally grown oxide layer thickness after 200-h oxidation at 1050 degrees C, and a 70.7 % unexpected extension of thermal cycling life. The crack-free glazed layer blocks oxygen and CMAS penetration, while nanoparticles react with CMAS to form Ca3ZrSi2O9 (acting as a sacrificial agent) and repair new cracks. This technique improves TBCs' high-temperature performance and offers broad applicability for defect sealing and optimisation in other coatings.

High-entropy alloys (HEAs) produced by laser additive manufacturing technology exhibit excellent comprehensive properties, holding significant potential for applications in extreme conditions. Laser polish (LP) technique has been innovatively applied to improve the high surface quality and tribological performance of the laser additively manufactured parts for practical applications. This study examined the impact of laser polishing on enhancing the surface quality and wear resistance of CoCrFeNi high-entropy alloy parts manufactured by the laser directed energy deposition (LDED) technology. The tribological behaviors of the LDED-ed HEAs parts before and after LP were analyzed by simulation analysis. The results indicate that after laser polishing, the surface roughness of the samples was reduced by over 96 %. The laser polishing process significantly refined the grain structure within the surface layer, altering the growth direction and orientation of the grains, and leading to a more uniform distribution of elements. The polished samples exhibited enhanced friction and wear characteristics compared to the original samples, as evidenced by a decrease in wear rate from 0.51 mm3 /(m center dot N) to 0.33 mm3 /(m center dot N), representing a reduction of approximately 33 %. Furthermore, the samples' wear mechanism was predominated by adhesive wear and abrasive wear prior to polishing. The wear mechanism underwent a transformation post-polishing, resulting in the coexistence of multiple wear mechanisms, with abrasive wear being the most prevalent.

The 6xxx-series Al alloys have been used for decades because of their favorable strength-to-weight ratio, corrosion resistance, and fatigue performance. However, conventional welding techniques often induce localized weakening, as thermal effects modify the microstructure and compromise structural integrity. For nearly 70 years, AA4043 welding wire has been the primary choice for joining 6xxx-series Al alloys. Nevertheless, microstructural and mechanical property mismatches between the base metal and weld region remain key factors contributing to premature failure, while welding-induced defects further increase rupture susceptibility. Microalloying has emerged as an effective strategy for enhancing both the mechanical and thermal properties of aluminum alloys. In this study, rare-earth (RE) elements La and Ce were introduced into the AA4043 system to exploit their grain refining and mechanical strengthening capabilities. In addition, the effects of Sr modification were examined and compared with La-Ce addition. This work aims to elucidate the strengthening mechanisms associated with La-Ce-Ti microalloying in AA4043 welding wire, a topic that has rarely been systematically investigated. With 0.019Ti-0.02La-0.03Ce additions, the modified wire exhibited significant performance improvements, achieving an UTS of 204 MPa and a YS of 191 MPa—representing increases of 10.3% and 18.6%, respectively.

Laser cladding technology has gained significant popularity for the preparation of high-entropy alloy (HEA) coatings. This is primarily due to its notable benefits, such as a low dilution rate and a robust bonding capability. However, the laser cladding process's rapid solidification effect and the high entropy impact led to the formation of defects in the coatings, such as non-uniform organization and elemental segregation. In this paper, the resonant ultrasonic vibration was used to regulate the organization and improve the microhardness and friction properties of the AlCuFeCoNi HEA coatings. The experimental findings demonstrate that ultrasonic vibration enhances both the width and depth of the coating's molten state, while simultaneously reducing the height of the coating. Before and after the introduction of ultrasonic vibrations, the coating consists of two phases, bodycentered cubic (BCC) and face-centered cubic (FCC). However, the magnitude of the FCC phase significantly increased with higher power. The internal grains of the coating were significantly refined by ultrasonic vibration, and the average grain size was refined from 68.34 mu m to 35.28 mu m, and the area occupied by equiaxial grains also increased with the increase of ultrasonic power, and the segregation of the FCC phase dominated by Cu elements was suppressed. When the ultrasonic power was 30 %, the microhardness of the coating was increased from 553.19 +/- 5.15 HV0.2 to 600.47 +/- 3.61 HV0.2. The addition of ultrasonic vibration increased the wear resistance of the coating and lowered the coefficient of friction from 0.558 to 0.409. Furthermore, the friction mechanism of the coatings before and after the addition of ultrasonic vibration did not change, and both were abrasive wear with slight oxidative wear.

Calcium-magnesium-alumino-silicate (CMAS)-induced degradation of thermal barrier coatings (TBCs) presents a significant challenge to their long-term durability in high-temperature environments including aircraft engines and gas turbines. In this study, a KrF excimer laser (248 nm wavelength) was used to glaze atmospheric plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) TBC surfaces. The high-energy ultraviolet photons from the excimer laser induced surface melting followed by solidification, producing a thin, dense glaze layer free of vertical cracks while preserving excellent thermal insulation performance. Accelerated CMAS corrosion tests were conducted at 1240 degrees C with exposure durations of 1 h and 12 h, simulating both short-term CMAS attack emergencies and long-term deposition accumulation scenarios encountered in practical applications. Under optimized laser parameters, the resulting similar to 1.5 mu m-thick glaze layer exhibited only ultra-fine nanocracks (<100 nm) without visible vertical cracking. The modified coating demonstrated outstanding resistance to molten CMAS attack at elevated temperatures. Notably, after 12 h CMAS exposure, the melt penetration depth was reduced by more than threefold compared to conventional APS TBCs, while phase stability and oxidation resistance were maintained. This surface modification approach offers promising potential for enhancing the reliability and lifespan of TBC systems in CMAS-rich environments.

Suppressed low-temperature toughness mismatch between the fusion zone (FZ) and base metal (BM) was achieved in a Q450NQR1 high-strength weathering steel joint by employing laser-arc hybrid welding (LAHW) with beam oscillation (O-LAHW), thereby avoiding the heat aggregation of conventional LAHW at the center of the molten pool. The O-LAHWed joint exhibited a higher content of acicular ferrite in the FZ, increasing it by 8

This paper primarily investigates the ultrasonic-assisted laser–MIG (metal inert gas welding) hybrid welding technology for TC4 titanium alloy, optimizing welding parameters by numerical simulation methods. An orthogonal experimental design was employed to optimize welding factors such as ultrasonic power, laser power, welding current, and welding speed. The results indicate that these parameters have a significant impact on molten pool morphology, residual stress distribution, and weld deformation. The study also shows that ultrasonic vibration helps to improve the fluidity of metal within the molten pool, thereby reducing welding defects; besides, it may also induce the instability of the molten pool. Finally, it is suggested that optimizing welding parameters can further reduce the residual stress peak value generated during the welding process and enhance the welding quality. This research provides a scientific basis for the application of TC4 titanium alloy in ultrasonic-assisted laser–MIG hybrid welding and promotes the application of this technology in high-tech fields.

Oscillation laser-arc hybrid welding (O-LAHW), which can homogenize the temperature distribution of the molten pool and the dynamic behavior of the liquid metal, is one of the most promising molten welding technologies, but there is a lack of research on the heat flow behavior of the molten pool and the homogenization mechanism. In this study, a numerical model coupling a high-speed rotating Gaussian laser heat source with a dual ellipsoidal arc heat source has been established, and a new Volume-of-Fluid (VOF) discrete algorithm is developed to realize the high-precision simulation of the O-LAHW of aluminum. The spatial evolution of the temperature and flow fields over one beam oscillation cycle was explored by means of slicing the transverse/longitudinal cross section of the molten pool. It is found that beam oscillation enhances temperature field uniformity, especially along the welding direction, improving by 30% compared to non-oscillating welding. Flow field of laser-arc hybrid welding (LAHW) analysis reveals significant velocity differences in different regions, with the laser-arc coupling zone experiencing continuous impacts, exacerbating keyhole fluctuations. O-LAHW reduces maximum velocity differences by 2.4 times, promoting stability. The high-speed circulation induced by beam oscillation alters the liquid metal flow direction in the coupling zone, preemptively redirecting shock waves caused by droplet transitions away from the laser keyhole. Additionally, backward-propagating liquid metal transports heat from droplets to the pool’s tail, disrupting micro-vortex circulation and enhancing flow stability and temperature uniformity throughout the molten pool. These findings are important for deepening the degree of understanding of the O-LAHW process and realizing the orderly regulation of the O-LAHW molten pool.

The design of the resonant ultrasonic vibration-assisted laser cladding (R-UVALC) setup involved employing finite element analysis (FEA) to simulate the ultrasonic transducer, horn, and workpiece in a resonance state. The impact of R-UVALC on AlCrFeMnNi high-entropy alloys was assessed using various ultrasonic vibration amplitudes of 0, 5, 10, and 15 µm, with a constant frequency of 20 kHz. Ultrasonic vibrations reduced pores and cracks and increased the clad breadth, melt pool wetting angle, and laser-clad layer consistency. The columnar elongated grains in proximity to the substrate surface underwent a size reduction and transformed into grains with a more equiaxed shape with the utilization of ultrasonic vibrations at an amplitude of 5 µm. Laser cladding performed without ultrasonic vibrations yields two phases: face-centered cubic (FCC) and body-centered cubic (BCC). However, when the coating is exposed to ultrasonic vibrations with an amplitude of 5 µm, it forms a solitary body-centered cubic (BCC) phase. The microhardness tripled compared to the substrate, and the most significant microhardness value was achieved at 5 µm of ultrasonic vibration. The friction coefficient was assessed at an ambient temperature, revealing that an ultrasonic amplitude yields the lowest friction coefficient, demonstrating the excellent wear resistance properties of the coating. The analysis of the 3D surface profile of the wear indicates that the use of ultrasonic aid with a 5 µm amplitude leads to reduced depth of scars, and the primary wear mechanism observed is abrasive and oxidative wear with fewer grooves and debris. In addition, XPS analysis revealed the presence of metal components in an oxidized condition, suggesting that the wear process is oxidative in nature. Integrating the R-UVALC setup into a resonance state can significantly enhance the efficiency of the laser cladding process in the laser cladding field.

Significance Metal melting and forming involves heating one or more types of metal to their melting point or above, allowing for alloying or metallurgical bonding. This process is utilized in methods such as welding, surface cladding, and additive manufacturing. Metal melting and forming technology has always advanced alongside human progress. At present, this technology is integral to aerospace, marine, and high- end equipment manufacturing, facilitating the formation, joining, and repair of metal structural components. However, the large temperature gradients that occur during metal melting and forming can have varying effects on structural metal parts. Welding, surface cladding, and additive manufacturing technologies involve the use of high- energy- density heat sources to melt metal materials in a confined area. The rapid cooling rate in these processes results in significant temperature gradients within the melt pool. This can lead to the predominant formation of columnar or dendritic crystal grains, which are prone to cracking and porosity under thermal stress, significantly affecting the performance of the workpiece. Regulating the internal structure of metal melting and forming parts and suppressing internal defects are critical issues in these processes. To address these challenges, researchers have proposed applying external physical fields-including electric, magnetic, and ultrasonic fields-during the metal solidification process. These fields interact with the molten metal to regulate its solidification structure. Initial studies have shown that ultrasonic vibration can refine grains, inhibit segregation, and reduce temperature gradients, thus positively impacting grain growth and solidification processes. Currently, the integration of ultrasonic vibration as an external energy field into metal melting and forming technology has become a research hotspot, offering potential solutions to enhance the quality and performance of metal parts. This study presents a discussion and summary of the recent progress and challenges in ultrasonic vibration- assisted metal melting and forming technology, focusing on its combined application with welding, surface cladding, and additive manufacturing. First, we briefly introduce the mechanism of ultrasonic vibration in metal melting. Then, we discuss the effects of ultrasonic vibration on metal melting and forming technology, considering different additive modes based on the ultrasonic transmission characteristics. Next, we explore the role of ultrasonic vibration in regulating the organization and properties of molded parts for casting, welding, surface cladding, and additive manufacturing processes. Finally, we identify the key scientific issues and technical challenges associated with ultrasonic vibration- assisted metal melting and forming technology. Progress In metal melting and forming technology, the excessive temperature gradients and rapid cooling rates often lead to significant non- equilibrium solidification structures. This results in issues such as grain size variation, solute segregation, and stress concentration. Ultrasonic vibration, a high- frequency mechanical vibration, induces several effects in molten metal, including cavitation, acoustic flow, mechanical, and thermal effects. Finite element simulation and experimental observations have revealed that these effects can effectively break down coarse grains, enhance melt flow, and reduce temperature gradients (Figs. 1-3). However, the high temperatures during metal solidification can significantly impact the working life of ultrasonic components. This study categorizes the various methods of incorporating ultrasonic vibration into metal melting and forming technology into contact and non- contact methods. Contact methods are further subdivided into below, side, and above, on the basis of the direction of ultrasonic vibration propagation in the metal melt. In the repair process of a small area, the time span is short; hence, the effect of ultrasonic vibration in different directions on the molding area is minimal. However, in the metal manufacturing process of a large area, the prolonged solidification process can intensify the impact of ultrasonic vibration, leading to significant differences in the molded parts based on the direction of ultrasonic vibration. This study compares the advantages and shortcomings of these methods in the application process (Table 1). Welding, surface cladding, and additive manufacturing are three typical metal melting and forming technologies. This study presents a literature review to explore the effects of ultrasonic vibration on these technologies from two perspectives: the microstructure and physical properties of the molded parts. The effects include gas exclusion, grain refinement, stress reduction, and enhancement of mechanical properties and corrosion resistance (Table 2). Conclusions and Prospects In this study, we review the research progress of ultrasonic vibration- assisted metal melting and forming technology. We discuss the mechanism of ultrasonic vibration in metal melts, various methods of adding ultrasonic vibration, and effects of ultrasonic vibration on the microstructure and physical properties of molded parts in welding, surface cladding, and additive manufacturing processes. This study summarizes the impact of ultrasonic vibration on the forming quality of various metal melting and forming technologies, seeking to aid the realization of high- quality metal melting and forming. We also aim to promote further research and application of ultrasonic vibration- assisted metal melting and forming technologies.

The weld surface characteristics of aluminum alloy fillet joints play a pivotal role in determining their performance. To enhance surface quality, oscillating laser-arc hybrid fillet welding was employed for aluminum alloy, along with a focus on the effect of beam oscillation on weld surface formation. Results revealed that a distinctive surface defect in aluminum alloy fillet welding manifested as a wavy edge on the main plate at oscillation frequencies (f) of 0 and 50 Hz. When f >= 150 Hz, the wavy weld edge was effectively suppressed. As a result, the tensile fracture location in the defect-free joint transferred from the main plate to the rib plate. The corresponding ultimate tensile strength reached 282.3 MPa, signifying a substantial 160.1 % improvement. Analysis indicated that the high-speed vortex generated by laser oscillation was the decisive factor in suppressing the wavy edge. This effect eliminated the depressed edge of the molten pool and mitigated droplet impact. Ultimately, a comprehensive examination of the forces acting on the molten pool unveiled the formation and suppression mechanism of the wavy edge. These insightful findings carry significant implications for enhancing the aluminum alloy fillet welding process and deepening comprehension of weld surface formation.

Cold metal transition (CMT) arc additive manufacturing (CMT-AM) technology can rapidly fabricate large-scale components, but encounters the challenges in improving efficiency, accuracy, and mechanical properties. Fortunately, oscillating laser -arc hybrid additive manufacturing (O-LHAM) provides a promising solution by stabilizing the arc at high current or high -speed, effectively addressing these issues. However, most studies primarily focus on thin-walled parts rather than entities, which are fabricated using multi -layer and multi -pass processes. The microstructure and mechanical properties vary with deposition strategies and greater heat accumulation. This paper therefore investigates the effects of deposition strategies on the formation, microstructure, and tensile properties of 100 mm x 100 mm x 70 mm O-LHAMed entities with a maximum feeding speed of 18 m/min. It is found that employing a continuous reciprocating deposition strategy without arc extinguishing within the same layer effectively avoids the mismatch between the actual and designed shape. At this stage, the deposition efficiency can reach 848 cm 3 /h, which is 2.25 times that of CMT-AMed parts reported in the literature. Deposition strategies do not affect the microstructures of different cross -sections of the entities. However, using multiple high currents facilitates the effect of solution heat treatment, leading to a transition in crystal solidification from ferrite-austenite mode in thin-walled parts to fully austenite mode, and ferrites within entity grains mostly disappear. Moreover, despite the deposition strategies exert minimal influence on the tensile properties, the entity fabricated using a 90 degrees continuous deposition strategy achieves an enhanced equilibrium among forming, microstructural, and performance due to its more random heat dissipation. The ultimate tensile strengths and elongations of all entities fall within the range of 518 - 544 MPa and 34.2 %-47.5 %, respectively, meeting the ASTM A479 standard. These findings greatly expand the potential applications of O-LHAM, facilitating the more efficient and high-quality fabrication of various metal parts, thus accelerating industrialization.

以汽车控制臂焊接构件作为研究对象,利用SYSWELD软件对控制臂构件的焊接热输入和焊接顺序进行优化.结果表明:当焊接热输入偏小时(2 015～2 266 J/cm),控制臂上下片之间的角焊缝焊根位置会出现未焊透缺陷;当焊接热输入适中时(2 527～2 701 J/cm),角焊缝能获得较好的焊缝熔宽和熔深.此外,对比分析不同焊接顺序下控制臂的残余应力和变形,发现采用先中间后两边(①④③⑤⑥②⑦⑧)的焊接顺序有利于降低控制臂整体的残余应力峰值;采用其它的焊接顺序时,控制臂整体的残余应力峰值较高,焊接变形也较大.试验与仿真结果对比表明,仿真结果的准确性较高,利用有限元仿真能优化汽车控制臂的焊接工艺,提高控制臂产品的焊接质量.

用3种不同Mg含量的ER5356铝合金焊丝对20 mm厚7A52铝合金进行MIG焊,研究Mg含量对熔滴过渡及电弧形态的影响,分析不同Mg含量焊丝对7A52焊接接头组织和性能的影响.结果表明:随Mg含量的增加,熔滴尺寸增加,过渡频率降低,焊接电弧产生的压缩作用减弱;焊缝区显微硬度提高,接头的抗拉强度提高,伸长率略有下降,断裂方式为韧性断裂;焊缝区等轴晶尺寸减小,Al3Mg2相增加;熔合区沿晶界处析出的Al3Mg2相增加,晶粒尺寸减小.当Mg的质量分数为5.0％～5.1％时,对裂纹扩展阻力大,焊缝中心延展性较好,抗拉强度为285.33 MPa,综合力学性能较好.