Hot Cracking Research Articles

Experimental Studies of Corrosion Resistance of Welded Seams of Steel Structures with a High Sulfur Content in Surface Layers Using Modern Methods of Modeling

Analysis of literature sources and empirical data indicate a variety and a large volume of experimental material, which often characterizes the uncertainty and contradiction of information regarding the effect of sulphur and manganese on the corrosion behaviour of steels obtained using traditional methods. This leads to the need to search for new, alternative methods for its effective analysis. The task of assessing and predicting the corrosion properties of structural steels is a key one in the general problem of managing the operational reliability of welded metal structures and equipment for the chemical, metallurgical, oil and gas, mining and other industries. The possibilities of its solution consist of using new information technologies, a component of which is intelligent means of information processing, such as artificial neural networks (ANN). The use of ANN makes it possible to create qualitatively new hardware and software that significantly expand the classes of emerging problems and increase the efficiency of analysis and forecasting. In the process of long-term operation of metal structures in many industrial industries, the metal is in direct contact with sulfur-containing agents at high temperatures. This leads to the saturation of the surface layer of the metal with sulfur with a concentration of up to 0.6%, which further makes it impossible to carry out repair and welding operations due to the formation of hot cracks. It was found that adding metallic manganese into the electrode coating in an amount of 20-25% significantly increases (4-5 times) the resistance against the formation of hot cracks. Sulfur content in the deposited metal has the opposite effect on the appearance of hot cracks. So, with a sulfur content of 0.042% and more, the resistance of the metal against the formation of hot cracks decreases sharply. It is shown that an increase in the content of metallic manganese in the electrode coating significantly reduces the content of dissolved sulfur in the deposited metal. Moreover, this tendency is typical for steels with different sulfur content in the surface layers and with different service life. For example, for steel with a service life of 20 years, the initial sulfur content in the surface layer of the metal (up to 1 mm) was about 0.52%. Adding metallic manganese in the coating of electrodes in an amount of 20-25% made it possible to reduce the sulfur content in the deposited metal to 0.03-0.045%, i.e. 12.6-17.3 times. In addition, the corrosion rate decreases with an increase in the content of metallic manganese in the electrode coating. The lowest corrosion rate for all steels involved in the research was established at 20-25% manganese content in the coating.

Integrated Control of Thermal Residual Stress and Mechanical Properties by Adjusting Pulse-Wave Direct Energy Deposition

Directed energy deposition with laser beam (DED-LB) components experience significant residual stress due to rapid heating and cooling cycles. Excessive residual tensile stress can lead to cracking in the deposited sample, resulting in service failure. This study utilized digital image correlation (DIC) and thermal imaging to observe the in situ temporal evolution of strain and temperature gradients across all layers of a deposited 316 L stainless steel thin wall during DED-LB. Both continuous-wave (CW) and pulsed-wave (PW) laser modes were employed. Additionally, the characteristics of thermal cracks and geometric dislocation density were examined. The results reveal that PW mode generates a lower temperature gradient, which in turn reduces thermal strain. In CW mode, the temperature–stress relationship curve of the additive manufacturing sample enters the “brittleness temperature zone”, leading to the formation of numerous hot cracks. In contrast, PW mode samples are almost free of cracks, as the metal avoids crack-sensitive regions during solidification, thereby minimizing hot crack formation. Overall, these factors collectively contribute to reduced residual stress and improved mechanical properties through the adjustment of pulsed-wave laser deposition.

Role of Ti-6Al-4V addition in modulating crack sensitivity, solidification microstructure and mechanical properties of laser powder bed fused γ-TiAl alloys

Solidification cracking is still the primary challenge for laser powder bed fusion (LPBF) without high-temperature preheating of γ-TiAl alloys. Circumventing the peritectic reaction and promoting β-solidification by adding the β-stablizing elements have been proved to be an effective way to suppressing the crack formation. In this work, we attempted a more economic method to realize β-solidification via the addition of Ti-6Al-4V (TC4) pre-alloyed powder. The results showed that the TC4 addition successfully changed the solidification path from L→L+β→L+α→α→α+γ→α2+γ to L→L+β→β→α+β→α2+β/B2. As a result, the solidified microstructure was mainly comprised of primary α2 phase and small amount of retained β/B2 (8.5 %) phase distributed along the molten pool boundary. What's more important was that the TC4 addition led to a 44.6 % decrease in crack density. Contributions to low hot cracking sensitivity were found to mainly origin from the relatively lower cooling rate, higher fraction of low-angle grain boundaries (LAGBs) and smaller dendrite coalescence undercooling induced by the TC4 addition. Besides, the smaller temperature interval (10.63K) in the final solidification stage (0.90<fs < 0.94) for the TC4/TiAl alloy was also conducive to facilitate the liquid feeding and dendrite coalescence.

Optimal TIG Welding Parameters of Dissimilar Aluminum Alloys 7075 and Al 6061 Using Ultrasonic Vibration and Nanocomposite Filler (Al 5356/ZrB2) to Alleviate Hot Cracking Phenomenon

Abstract In this study, the welding of dissimilar aluminum alloys, Al 7075 and Al 6061, was investigated using Al 5356 filler rods reinforced with ZrB2 particles. The welding process was conducted using TIG welding, with and without ultrasonic vibration, to enhance weld quality and reduce hot cracking. Optimization of process parameters for dissimilar TIG welding was performed through Response Surface Methodology (RSM), which generated a design matrix to analyze the influence of process parameters on response variables. Numerical and graphical optimization were applied to minimize hot cracking sensitivity and maximize microhardness. The RSM-based models suggested an optimal welding current of 93A, the use of Al 5356/ZrB2 nanocomposite filler, and the application of ultrasonic vibrations. Experimental validation of the identified solution demonstrated improvements in weld quality, including increased yield strength and ductility. The combination of nano-reinforced fillers and ultrasonic vibrations was found to enhance weldability and mitigate hot cracking in dissimilar aluminum joints. The mechanism of hot cracking reduction involved grain refinement, degassing, and homogenization due to ultrasonic vibrations, as well as the modification of weld pool chemistry and control of dilution by the nanocomposite filler, which collectively minimized solidification shrinkage and stress. Under these optimized conditions, no hot cracking was observed experimentally.

Crack analysis in laser powder bed fusion-fabricated 2195 Al-Li alloy: An in-depth examination of influential variables

Laser powder bed fusion (LPBF) of high-strength 2195 Al-Li alloys offers significant industrial potential, yet the process is hindered by a high susceptibility to hot cracking. This study systematically investigates the hot cracking mechanisms and the key processing parameters influencing crack formation in LPBF-fabricated 2195 Al-Li alloys. Extensive experimental analysis revealed that crack density is significantly affected by scanning velocity and laser power, with scanning velocity identified as the most critical factor through a neural network model and a crack susceptibility model. The study demonstrates that achieving crack-free samples requires extremely low scanning velocities, as higher velocities exacerbate crack formation, particularly at high-angle grain boundaries (HAGBs). The findings also highlight the limitations of preheating in reducing crack susceptibility, emphasizing the importance of precise control over processing parameters to mitigate cracking in LPBF-fabricated 2195 Al-Li alloys.

Research on the micro-mechanism and factors of hot recycled asphalt binder cracking

The poor low-temperature performance of recycled asphalt is the primary cause of the recycled asphalt disease. However, further strengthening is required to analyze the molecular-level cracking of recycled asphalt. This article presented a comprehensive investigation of the cracking phenomenon of recycled asphalt at both the macro and micro levels. This was achieved through the utilization of experimental tests and molecular dynamics simulations. In this study, pressure-aged asphalt was subjected to 40 h of aging. The aged asphalt was divided into three groups: 30% RAP (reclaimed asphalt pavement) recycled asphalt, 50% RAP recycled asphalt, and 70% RAP recycled asphalt. The three groups were then analyzed in terms of three major indexes. Linear amplitude scanning (linear amplitude sweep, LAS) was conducted on the three groups. The mechanical response law of asphalt was obtained, and it was found that the coefficient of strength of recycled asphalt increased with the increase of RAP dosage. At the same time, the fracture energy density decreased subsequently. Furthermore, the fracture energy density of aged asphalt was 7% lower than base asphalt's. Subsequently, this study examined the four fractions and C=O and S=O functional groups of five types of asphalt and constructed the molecular structures and models of stable base asphalt and aged asphalt. Subsequently, this article constructed a fusion model of new and old asphalt, analyzed the fusion process of new and old asphalt, and studied the factors affecting the blending degree of new and old asphalt. Finally, the factors affecting the cracking performance of rejuvenated asphalt, including the blending degree, the content of the four fractions, and the addition of the rejuvenator, were investigated. The impact of each influencing factor on the cracking performance of recycled asphalt was analyzed from multiple perspectives. In conclusion, the findings of this study provide a valuable guide for interpreting the tensile properties of reclaimed asphalt and the influence of rejuvenators.

Nanoparticle-enabled additive manufacturing of high strength 6061 aluminum alloy via Laser Powder Bed Fusion

Wrought aluminum alloy AA6061 is widely used in automotive, aerospace, and other industries due to its good properties, including high strength, excellent corrosion resistance, and good weldability. However, when using Laser Powder Bed Fusion (LPBF) for AA6061, hot cracking becomes a serious problem. In this work, AA6061 powder with internally dispersed nanoparticles has been adopted in a LPBF process. Through optimization of printing parameters, components with minimal porosity (less than 0.5 %) have been successfully produced without cracks. Additionally, by employing a chessboard printing strategy to create finely detailed cellular and grain structures, we have achieved significantly enhanced mechanical properties in its as-printed state for AA6061. These components exhibit an impressive yield strength (YS) of 233 MPa and ultimate tensile strength (UTS) of 310 MPa while maintaining a ductility of approximately 10 %. This performance surpasses that of commercial AA6061 and other Al-Si alloys, establishing it as a high-strength material suitable for various applications.

Nanotechnology enabled casting of aluminum alloy 7075 turbines

Aluminum alloy 7075 is well-known for its high-performance structural systems due to its lightweight and excellent mechanical properties. However, its susceptibility to hot cracking and limited fluidity hinder its casting suitability, posing challenges in manufacturing near-net-shaped structures economically, especially for thin and intricate aerospace components. This paper presents experimental results based on nano-treating, an emerging nanotechnology-enabled manufacturing method by incorporating a low fraction of nanoparticles in liquid aluminum, to allow the casting of complex aluminum alloy 7075 parts. Vacuum fluidity tests demonstrated that nano-treating of aluminum alloy 7075 with only 0.5 vol% TiC nanoparticles increased the fluidity of aluminum alloy 7075 by more than 20%, effectively eliminating hot cracking and enhancing surface quality. Through the Rapid Investment Casting process, nano-treated aluminum alloy 7075 can be successfully cast into turbines with 0.5 mm thick blades. In contrast, aluminum alloy 7075 without nano-treating failed to produce good casting quality due to poor filling and severe cracks. The manufacturing trials highlight the significant improvement in castability achieved through nano-treating, opening a novel pathway for the cost-effective production of complex aluminum alloy 7075 structures for numerous applications.

Establishment of Multi-Physics coupling model and analysis on thermal stress and crack risk in directional growth of TiAl alloys under electromagnetic confinement

The electromagnetic confinement directional solidification (EMCDS) technique is an optimal method for preparing large-size and non-contamination directional TiAl alloy crystals. Despite its advantages, the high temperature gradient inherent to this process induces thermal stress within the ingot, which increases the risk of cracking. To address this challenge, an innovative Integrated Multi-Physics Coupling Model was established to map and study the thermal stress field during EMCDS in this study. It synchronized the computation of the electromagnetic field, temperature field, solute field, flow field, and stress field during the crystal growth of TiAl alloy, and its high accuracy was proved by the micro-indentation experiment. Our analysis reveals that transverse temperature differences are crucial in inducing thermal stresses, and identifies that hot cracks and cold cracks are prone to occur respectively at the area of radial 23R along the sample (X = 23R) and on the sample surface, which aligns with experimental observations impressively. This model can more accurately and efficiently optimize the process parameters of the EMCDS process to avoid cracks and promote its industrial application.

Enhancing machinability in free-cutting duplex brass alloys: Isotropic blocky α phase formation via optimized hot extrusion processing

Despite the active utilization of duplex brass alloys in the electronics and automotive industries, optimizing thermomechanical treatment conditions for achieving excellent machinability remains a subject of ongoing debate. In this study, to establish a strategy to achieve enhanced machinability via industrial-scale direct hot extrusion processing, we systematically investigated the effect of hot extrusion processing conditions on microstructural evolution, mechanical properties, and machinability of duplex brass alloys. In particular, the yield strength was effectively interpreted through the extended Hall-Petch relationship, and the machinability was further elucidated through the evaluation of rotational torque during the drilling test as well as the precise analysis of segmented chips produced in the drilling test. As a result, our microstructural analysis of the as-cast Cu58Zn39Pb3 alloy revealed that the cooling process during industrial-scale casting inevitably results in the formation of the Widmanstätten structured α phase and the heterogeneous dispersion of Pb particles. In contrast, 670 ℃ extruded lower part and 730 ℃ extrudates, which were extruded in the single β region that caused complete dynamic recrystallization behavior, exhibited a uniform and isotropic blocky α structure and uniformly redistributed Pb particles, ultimately leading to superior mechanical properties and machinability. Notably, our findings suggest that achieving an isotropic blocky α structure can be attained at temperatures up to 100 ℃ below the β-transus temperature by optimizing extrusion pressure conditions. This approach offers an efficient methodology for minimizing defects caused by high-temperature extrusion, such as surface oxidation and hot shortness cracking, while simultaneously minimizing processing costs.

Nanotechnology-enhanced castability of wrought aluminum alloys 2024 and 6063

In the realm of high-performance applications, wrought aluminum alloys are esteemed for their high mechanical properties and excellent strength-to-weight ratio. However, their limited castability poses challenges in economically producing intricate structures through casting processes. To address this issue, a small proportion of TiC nanoparticles is introduced into the melts of AA 2024 and AA 6063 for nano-treating. This nano-treatment imparts several beneficial effects, including the delayed release of latent heat, inhibition of grain growth, and improvement of wettability. These effects enhance the fluidity of the melt, eliminate hot cracking, and elevate the surface quality of the castings. The outcomes underscore the promising potential of emerging nano-treatment technology in rendering traditionally non-castable wrought aluminum alloys suitable for cost-effective casting processes, ultimately delivering high-performance products for a wide range of applications.

Study on welding process of stainless steel/superalloy dissimilar materials

Abstract In this study, dissimilar materials of 321 stainless steel, S-03 stainless steel, and GH3030 superalloy were selected and the argon tungsten-arc welding method was used to explore the welding parameters. The microstructure and properties of three materials after welding were studied. The main mechanism of welding cracks was analyzed by optical microscope and scanning electron microscope. Reasonable welding parameters were established and the dissimilar welding process was realized. The experimental results show that the cracks produced by welding of the three materials are typical welding hot cracks. The crack source originated from the bottom layer and extended to the surface of the welded joint. The main reason for cracking is the formation of low melting point compounds by the segregation of S and Ti elements during the process of self-melting. The welding process of the dissimilar materials can be realized by multi-pass filling welding. Increasing welding speed and reducing heat input are effective ways to improve weld mechanical properties of the welded joint.

Prevention of hot cracking in Ni-based superalloy via passivation layer formation during additive manufacturing

We investigated the prevention of hot cracking in a non-weldable Ni-based superalloy by utilizing a passivation layer formed through laser-based directed energy deposition. The addition of Hf to the Ni-based superalloy facilitated the formation of a passivation layer consisting of Hf oxide on the surface of the as-deposited sample. An increase in the amount (thickness) of the passivation layers with increasing Hf content resulted in a reduction in hot cracking occurrence. Specifically, the addition of 2.5 wt% Hf led to the formation of uniformly distributed fine oxides without inducing hot cracks. This passivation layer effectively inhibited the formation of coarsened Mo oxides, which typically occur during oxidation in the liquid state and contribute to the hot cracking of Ni-based superalloy. During oxidation in the liquid state, Hf diffuses out to the surface and forms a passivation layer, thereby suppressing the formation and growth of oxides to sizes large enough to induce hot cracking.

Determination of the load acting on the probe by separating force and torque during FSW of AA 6060 T66

AbstractThe development of suitable welding processes is required to meet the ever-increasing demands on joining processes, particularly for lightweight construction and increasing environmental awareness. Friction stir welding (FSW) represents a promising alternative to conventional fusion welding processes, particularly for the joining of low-melting-point materials such as aluminium and magnesium alloys, which present a number of challenges, including the formation of pores and the occurrence of hot cracks. The central element of the process is the friction stir welding tool, which consists of a shoulder and a probe. The rotation and the simultaneous application of pressure during the joining process create a friction-based heat input through the tool. The excellent mechanical properties resulting from dynamic recrystallisation during the welding process are a major advantage of the process. As a result, strengths comparable to those of the base material can be achieved. However, FSW is subject to process-specific challenges, including high process forces, which result in the fabrication of complex and robust devices. Additionally, high dynamic loads on the friction stir welding tools must be considered. In many cases, the design of friction stir welding tools is based on empirical data. However, these empirical values are machine-, component- and material-specific, which often results in under- or overmatching of friction stir welding tools. Sudden probe failure, component scrap, and low process reliability are the direct consequences of undermatching. Overmatching results in enlarged tools with limited accessibility, high heat input, and high process forces, leading to component deformation. The aim of this study is to determine the load on the probe by separating the forces and torque of the shoulder and the probe in order to be able to make statements about the load acting on the probe and the resulting stress state. The knowledge of the stress state can be employed to design friction stir welding tools, both statically and dynamically, for a specific welding task. A strategy was devised to distribute the load exerted on the shoulder and probe. To this end, the length of the probe was gradually reduced between the welding tests. The investigations were carried out with a force-controlled robotized welding setup in which AA 6060 T66 sheets with a thickness of 5 mm were welded. A Kistler multicomponent dynamometer type 9139AA allows to measure the Cartesian forces to be recorded in the x-, y-, and z-directions with a sampling rate of 80 kHz. The weld seam properties were determined by visual and metallographic inspections as well as tensile and bending tests in accordance with DIN EN ISO 25239–5.

Alternatives to Reduce Hot Cracking Susceptibility of IN718 Casting Alloy Laser Beam Welds with a Mushroom Shape

Reducing hot cracking is essential for ensuring seamless production of nickel superalloys, which are extensively used in welded structures for aircraft engines. The prevalence of hot cracking in precipitation-strengthened alloy 718 is primarily governed by two factors: firstly, the chemical composition and the coarse microstructure formed during solidification, and secondly, the activation of hot cracking mechanisms, which is particularly critical in mushroom-shaped welding morphologies. In this study, different nickel-based superalloys welded using laser beam welding (LBW), more specifically bead on plate welding (BoP), specimens are compared. The cracking susceptibility of both wrought and two investment casting 718 alloys with tailored chemical compositions is examined through the application of both continuous and pulsed LBW. Additionally, various pre-weld treatments, including with and without Pre-HIP (hot isostatic pressing), are analyzed. The influences of chemical composition, LBW parameters and pre- and post-welding treatments on both internal and external cracks determined by conventional and advanced non-destructive tests are studied. A clear reduction of hot cracking susceptibility and overall welding quality improvement was observed in a tailored 718 alloy with relatively high Ni (55.6% wt) and Co (1.11% wt) contents.

Jet on demand—A pneumatically driven molten metal jetting method for printing crack-free aluminum components

Additive manufacturing (AM) of many traditional aluminum alloys is difficult due to hot cracking during cooling, which motivates investigating alternative AM methods that can mitigate this challenge. Here we demonstrate a new pneumatically driven molten metal jetting (MMJ) AM technique which uses a longer pressure pulse width to produce a jet of liquid metal that reaches the heated build plate. The “jet on demand” technique is utilized to build Al-6061 parts on heated build plates. Due to the large thermal mass contained in each jet, excellent adhesion is observed between droplets and layers while still maintaining dimensional control to produce parts with high relative densities (>98%). While as-printed parts exhibit different microstructure and hardness than traditional Al-6061, both microstructure and hardness are restored to traditionally processed values through a traditional T6 heat treatment. Microhardness values of 104 HV were obtained for printed Al-6061, which compares well to wrought properties. We observe that high build plate temperatures allow for lower solidification rates and eliminate hot cracking. These results point to a method for additively manufacturing traditional aluminum or other alloys that cannot currently be additively manufactured due to hot cracking.

Determination of critical local straining conditions for solidification cracking at laser beam welding by experimental and numerical methods

AbstractThe phenomenon of solidification cracking has been the subject of numerous research projects over the years. Great efforts have been made to understand the fundamentals of hot cracking. It is generally agreed that solidification cracks form in the solidification range between the liquidus and solidus temperatures under the combination of thermal, metallurgical and mechanical factors. There is still a need to determine the time‐resolved strain distribution in the crack‐sensitive region in order to analyse the local critical conditions for solidification cracking phenomena. This was a strong motivation for the development of a measurement system used in this study to estimate the local strains and strain rates in the zone where the solidification crack is expected to occur. The laser beam welding experiments were conducted using the Controlled‐Tensile‐Weldability test (CTW test) to apply an external strain condition during welding to generate solidification cracks. The CTW test is a test method for investigating the susceptibility of laser‐welded joints to solidification cracking, in which the sample can be subjected to a defined strain at a defined strain rate during welding.In combination with experimental investigations, numerical simulations provide spatially detailed and time‐dependent information about the strain development during the welding process, especially regarding the critical conditions for solidification cracking. Therefore, this tool was also used in the present study to evaluate the accuracy of measurement methods and to estimate experimentally derived values and their concrete influence on the formation of solidification cracks. By integrating experimental methods and numerical simulations, this study investigates the spatially resolved and temporally changing development of strain during welding, with a particular focus on the critical conditions that lead to the formation of solidification cracks. The use of numerical simulations serves a dual purpose by validating the accuracy of measurement methods and examining experimentally determined values for their actual influence on the formation of solidification cracks. A three‐dimensional finite element (FE) model implemented with ANSYS is used to simulate strains and stresses during welding. The credibility of the model was first established by validation using experimental temperature measurements. Subsequently, structural simulations were carried out under external load. The results of the simulations showed commendable agreement with the strain measurements performed using the developed technique.

Elucidation and verification of cracking behavior in additive manufacturing of alloy 718 based on fractography

This study identified a cracking that occurred continuously in the built direction of an additive manufactured part of alloy 718 by the laser metal deposition method and clarified the cracking behavior. The solidification microstructure of alloy 718 was evaluated by EDS, EPMA, and extraction residue, and it was found that Laves phase, Ti carbides, and Al oxides were formed between the dendrite microstructures. A fracture surface analysis of the cracks revealed that the cracking in the additive manufacturing was hot cracking associated with the liquid film and that the cracking occurred along the grain boundaries. The fracture surface at the beginning of the cracking showed a solidification cracking fracture surface. The experimental investigation for crack propagation during additive manufacturing and the analytical evaluation of the mechanical state around the cracking using thermal elastic-plastic analysis elucidated the cracking behavior during additive manufacturing. If the cracking exists at the fusion boundary, it is suggested that the cracking initiates from the solid-liquid interface towards the solidification direction. Moreover, tensile strain occurred around the cracks during additive manufacturing, particularly the strain was biggest at the crack edge on the fusion boundary. Therefore, the continuous cracking that occurred beyond each layer in the additive manufacturing of alloy 718 in this study can be considered solidification cracking, and its behavior can be further explained as a notch extension cracking that starts from the solidification cracking and continuously occurs in the solid-liquid coexistence temperature region.

Detection of Hot Cracking for 6000 Series Aluminum Alloys using a Multi-Sensor Based Deep Learning Model

This study developed a monitoring technology using a multi-sensor based deep learning model to diagnose hot cracking in aluminum alloy laser welding. Hot cracking that occurs during the laser welding process of aluminum alloys is difficult to diagnose accurately with a single sensor signal, necessitating multi-sensor based process monitoring technology. To monitor these hot cracks, laser-induced plasma, acoustic, and elastic wave signals were simultaneously measured using a spectrometer, non-contact acoustic sensor, and contact acoustic sensor during the overlap laser welding process of 6000 series aluminum alloys. The welded specimens were classified into normal and cracked specimens through bead analysis, and features related to hot cracking were extracted from each sensor signal to utilize the measured multi-sensor signals for monitoring. The extracted features from each signal were used as inputs for a Deep Neural Network (DNN) model capable of learning complex nonlinear relationships, and the hyperparameters of the DNN model were optimized using a genetic algorithm. The DNN model trained with multi-sensor data diagnosed hot cracking with an accuracy of 93.75%.

Study on molten pool flow and hot cracking of narrow gap laser welding of 316LN stainless steel for fusion reactor

In this paper, narrow-gap laser welding (NGLW) of 316LN stainless steel was studied. The results indicated that continuous laser welding with filler wire (CLWFW) and pulsed laser welding with filler wire (PLWFW) can obtain good weld formation under the transition of the wire bridge, and when the pulsed laser was a trapezoidal wave, the hot cracks of the filling layer can be greatly inhibited. The intermittent output of the pulsed laser reduced the temperature gradient of the molten pool and enhanced the morphology of the caudal region of the molten pool. Meanwhile, timely liquid backfilling effectively relieved the stress concentration of the weld, thus inhibiting the generation of hot cracks. Besides, the intermittent pulse energy input had a stirring effect on the molten pool, which disturbed the growth direction of the dendrite grain and refined the grain; consequently, the impurity elements were fully diffused, and the distribution of elements in the weld center area was more uniform.