Decreasing Laser Power Research Articles

Effect of gradually decreasing laser power on the microstructure and properties of laser melting deposited Inconel 718Plus alloy thin-wall

Laser melting deposition (LMD) technology offers a novel method for fabricating superalloy thin-walled parts because of its significant advantage of rapidly producing near-net-shape moldings. However, the coarse columnar crystals in these deposited thin-walled parts resulted in poor mechanical properties, which significantly limited its wide application. To address this problem, a layer-by-layer decreasing laser power deposition strategy (LT) is proposed in this study, which can increase the cooling rate of the molten pool by reducing the thermal cycling. Results indicate that the thin walls of Inconel 718Plus alloy deposited by the LT strategy exhibit dendrites at heights of 4.5 mm (bottom region), 16.5 mm (middle region) and 28.5 mm (top region). The Laves phase at the bottom of the LT alloy thin-wall was randomly distributed granular, which gradually transformed into granular, short-chain and its mixed structures with increasing height. Formation of long-chain Laves phases was hindered by the connection of dendrites. The densely distributed granular Laves phase in the LT strategy alloy thin wall could effectively transfer and dispersed the stress and hindered the crack initiation and extended. Compared to the bottom region, the yield strength of the LT alloy thin-wall in the middle and top region increased by 6.7 % and 12.6 %, and the tensile strength increased by 10.7 % and 16.2 %. In conclusion, the alloy thin-walls fabricated by the LT strategy exhibit superior strength and more balanced mechanical properties.

Influence of Remote Laser Cutting on Magnetic Loss and Mechanical Properties in 0.2 mm Silicon Steel

Energy loss due to eddy current generation is a significant factor in reduced efficiency of electrical machines, therefore motor cores with thinner sheets are required due to their effect in reducing eddy currents. However, reducing the thickness of laminations is challenging due to the high tooling costs in blanking due to the small tolerances required, whilst other methods such as conventional laser cutting are too slow to be commercially viable. In this paper the influence of remote laser cutting on thin electrical steel sheets (Cogent/Tata Steel NO20 3.2% Si) has been investigated on the tensile strain to fracture, fatigue life, edge hardness, and energy loss in an AC magnetisation cycle for two laser power levels. The laser power has found to have no statistically significant influence on the bulk mechanical properties of the material, but significantly affects the measured specific loss. The latter was associated with the increased edge hardness at higher laser powers. Based on the parameters selected it is highly questionable whether RLC offers a viable method for lamination cutting, significant refinement of the laser parameters and/or the use an alternative laser such as an ultra-fast pulsed laser is required to be competitive with existing methods. Additionally, it is shown that energy loss increases linearly with respect to length of the cut edge - to the minimum cut spacing tested of 6 mm. These results can be used to optimise laser parameters to reduce the degradation of magnetic properties by decreasing laser power where possible.

The Effect of Process Parameters on the Temperature and Stress Fields in Directed Energy Deposition Inconel 690 Alloy.

Additive manufacturing (AM) technology has the advantages of designability, short process times, high flexibility, etc., making it especially suitable for manufacturing complex high-performance components for high-end industrial systems. However, the intensive temperature gradients caused by the rapid heating and cooling processes of AM can generate high levels of residual stresses, which directly affect the precision and serviceability of the components. Taking Inconel 690 alloy, which is widely used in nuclear power plants, as the research object, a thermo-coupled mechanical model of temperature field and residual stress field of directed energy deposition (DED) of Inconel 690 was established based on ABAQUS 2019 finite element software to study the influence of process parameters on the temperature history and the distribution of residual stresses in the DED process. The experimental results show that the peak temperature of each layer in the fabrication process increases with the increase in laser power and preheating temperature, and decreases with the increase in scanning speed and interlayer dwell time. Substrate preheating only has a large effect on the peak temperature of the first four layers. Residual stresses are mainly concentrated in the upper and middle parts, the bottom of the substrate, and the sides combined with the substrate, and the residual stresses increase with the increasing laser power and decrease with the increasing interlayer dwell time. Decreasing laser power, longer dwell time, higher preheating temperature, and appropriate scanning speed are beneficial for the reduction in residual stresses in Inconel 690 components. This research has important significance for the process design and residual stress modulation in the additive manufacturing of Inconel 690 alloy.

Influence of thermal loading parameters and microstructure on the formation of stratified surface layers on railway wheels

Due to an increasing trend towards environmentally friendly public transport, rail networks face higher speeds and wheel loads affecting the material degradation of the railway components. Within this study, influencing parameters on the formation of stratified surface layers, forming on railway wheels during service due to thermal loadings in the wheel-rail contact, are studied. These layers consist of white etching layer and underlying brown etching layer and are susceptible to fatigue crack initiation. By using laser surface treatments, its formation based on two consecutive thermal loadings is systematically demonstrated on ER7 wheel steel. Further, a decrease in layer thickness with decreasing laser power, and an increase in brown etching layer thickness with increasing laser power difference is shown. Moreover, the effect of finer grain size leading to an increased layer thickness, and the influence of the chemical composition by comparing the standard ER7 wheel steel to a micro-alloyed wheel steel are demonstrated.

Resilience of laser powder bed fusion additive manufacturing to programmatically induced laser power anomalies

Spatter interactions, varying power or scanner parameters, and uneven powder spreading in laser powder bed fusion (LPBF) can trigger the formation of lack-of-fusion or keyhole pores. In this paper, a strategy to mimic natural process anomalies is developed by varying the programmed laser power in a predefined region over sequential layers in order to understand the physics of pore formation and enable the systematic study of the sensitivity of LPBF processed Ti-6Al-4V to process anomalies. Results indicate that lack-of-fusion pores, caused by a decreased laser power input, and located at a depth equal to or less than the subsequent melt pool depth, are partially or fully healed by subsequent, nominally processed layers. Under conditions tested here, lack-of-fusion pores as deep as two layers (∼120 μm) below the surface are healed on subsequent layers. Conversely, local increases in laser power cause persistent keyhole pores, owing to the depth at which keyhole pores become entrapped into the melt—in this work, up to eight layers or 420 μm deep. These results show that while keyhole-induced porosity remains unaffected by the processing of subsequent layers, LPBF is resilient to a set of process anomalies, which would result in lack-of-fusion if not for subsequent remelting on layers above.

Enabling Self-Induced Back-Action Trapping of Gold Nanoparticles in Metamaterial Plasmonic Tweezers.

The pursuit for efficient nanoparticle trapping with low powers has led to optical tweezers technology moving from the conventional free-space configuration to advanced plasmonic systems. However, trapping nanoparticles smaller than 10 nm still remains a challenge even for plasmonic tweezers. Proper nanocavity design and excitation has given rise to the self-induced back-action (SIBA) effect offering enhanced trap stiffness with decreased laser power. In this work, we investigate the SIBA effect in metamaterial tweezers and its synergy with the exhibited Fano resonance. We demonstrate stable trapping of 20 nm gold particles with trap stiffnesses as high as 4.18 ± 0.2 (fN/nm)/(mW/μm2) and very low excitation intensity. Simulations reveal the existence of two different groups of hotspots on the plasmonic array. The two hotspots exhibit tunable trap stiffnesses, a unique feature that can allow for sorting of particles and biological molecules based on their characteristics.

Evaluation of particle release during cleaning of coated surfaces with pulsed Nd:YAG laser

The released particles during laser-based surface ablation of an epoxy resin coating were investigated for their number, size, mass and chemical composition. The laser used was a pulsed Nd:YAG laser with a maximum average power of 91 W. During the experiments, the applied laser power was investigated as a varying parameter. With the highest power, a maximum particle count of 4.3*108 particles/cm³ was measured, which corresponds to a mass of approximately 55 mg/m³. With decreasing laser power, the particle loading of the aerosol decreases. The particle sizes are bimodal distributed between 10 nm and approximately 3 μm. The first peak is at 34 nm and the second peak is at 630 nm. In terms of number, the nanoparticles dominate the distribution. During the analysis of the particles, fractal and spherical particles were determined, whereby the fractal particles are mainly in the nanometre range and the spherical particles mostly in the μm range. The chemical analysis of the particles showed that they consist of carbon and hydrogen.

Selective laser melting of Ti6Al4V alloy: effects of process parameters at constant energy density on mechanical properties, residual stress, microstructure and relative density

Abstract Selective laser melting is a production method that results in a large amount of residual stress due to high cooling rates and high thermal gradients. Although there are many studies examining the effects of process parameters on residual stress or mechanical properties in the literature, there are a few studies investigating the effects of changing laser power and scanning velocity (exposure time) at constant energy density on residual stress or mechanical properties and these studies have different results. This is a comprehensive study in this field that includes detailed comparisons with the results of similar studies in the literature. In this study, firstly specimens were produced at different process parameters and it was tried to find the process parameters that will obtain the highest relative density among the trials. Then at the constant energy density (85.0 J mm−3), which the maximum density has been obtained the effects of changing laser power and scanning velocity on residual stress, mechanical properties, microstructure and relative density were investigated. It was observed that at constant energy density, increasing or decreasing laser power and scanning velocity did not increase or decrease residual stress, tensile strength, % elongation and relative density monotonously.

Simulation Analysis of Stress Field of Walnut Shell Composite Powder in Laser Additive Manufacturing Forming

A calculation model of stress field in laser additive manufacturing of walnut shell composite powder (walnut shell/Co-PES powder) was established. The DFLUX subroutine was used to implement the moveable application of a double ellipsoid heat source by considering the mechanical properties varying with temperature. The stress field was simulated by the sequential coupling method, and the experimental results were in good accordance with the simulation results. In addition, the distribution and variation of stress and strain field were obtained in the process of laser additive manufacturing of walnut shell composite powder. The displacement of laser additive manufacturing walnut shell composite parts gradually decreased with increasing preheating temperature, decreasing laser power and increasing scanning speed. During the cooling process, the displacement of laser additive manufacturing of walnut shell composite parts gradually increased with the increasing preheating temperature, decreasing scanning speed and increasing laser power.

Influence of anti-phase surface relief structure on optical mode and laser output power for 450 nm GaN-based VCSELs

For GaN-based vertical-cavity surface-emitting lasers (VCSELs), single-mode output and high power are difficult to be achieved simultaneously. In this report, we propose increasing the output power while taking the optical field into account by engineering the anti-phase surface relief structure and current aperture size for GaN-based VCSELs. We find that the proposed anti-phase surface relief structure helps to get Gaussian-shaped near-field and far-field patterns for VCSELs. However, such structure suffers from mirror loss and causes decreased laser power. Hence, the current injection aperture size has to be reduced so that the overlap level between the carrier profile and the anti-phase surface relief region can be decreased. Therefore, the VCSEL structure with enhanced laser power and dominating fundamental laser mode can be finally designed.

Experimental Investigation on Compressive Strength, Ultrasonic Characteristic and Cracks Distribution of Granite Rock Irradiated by a Moving Laser Beam

Efficient fracturing is the key issue for the exploitation of geothermal energy in a Hot Dry Rock reservoir. By using the laser irradiation cracking method, this study investigates the changes in uniaxial compressive strength, ultrasonic characteristics and crack distributions of granite specimens by applying a laser beam under various irradiation conditions, including different powers, diameters and moving speeds of the laser beam. The results indicate that the uniaxial compressive strength is considerably dependent on the power, diameter and moving speed of the laser beam. The ultrasonic-wave velocity and amplitude of the first wave both increase with a decreased laser power, increased diameter or moving speed of the laser beam. The wave form of irradiated graphite is flattened by laser irradiation comparing with that of the original specimen without laser irradiation. The crack angle and the ratio of the cracked area at both ends are also related to the irradiation parameters. The interior cracks are observed to be well-developed around the bottom of the grooving kerf generated by the laser beam. The results indicate that laser irradiation is a new economical and practical method that can efficiently fracture graphite.

A digital twin of synchronized circular laser array for powder bed fusion additive manufacturing

The formation of undesirable microstructures and defects hinders the widespread use of additive manufacturing, e.g., the formation of columnar grains in Ti–6Al–4 V leads to undesirable anisotropic mechanical properties. Here, we investigate the application of a novel synchronized circular laser array in the powder bed fusion technique to alter the microstructure of printed parts toward the preferable equiaxed grains. This feat is not achievable with the single laser powder bed fusion technique for Ti–6Al–4 V alloy. The temporal temperature distributions for different process parameters (laser power, scanning speed, and internal distance between lasers in the array) were obtained by an anisotropic heat transfer model, and the Hunt criterion was employed to construct the solidification map. The results revealed that a degree of overlap between lasers is recommended to form a coherent melt pool, avoid degeneracy in surface quality, and maintain adequate resolution for all processing windows. However, laser overlap is not required for low scanning speed and high power scenarios. Finally, microstructure prediction shows that 45% of printed track includes equiaxed grains at a high power regime (500 W). However, the volume fraction of the equiaxed microstructure is reduced by decreasing laser power.

Research on the temperature control strategy of thin-wall parts fabricated by laser direct metal deposition

To solve the problem that the macro-size, microhardness, and mechanical properties of the laser direct metal deposition (DMD) of thin-walled parts are inconsistent due to the heat accumulation, an improved three-dimensional finite element heat propagation model was developed to simulate the temperature evolution of the single-pass multi-layer thin-walled parts. The results show that the heat accumulation is contributed to the transformation of the heat dissipation mechanism from three-dimensional to two-dimensional, while the residual heat of the former layer has no significant effect on the heat accumulation of the current layer. The optimized strategy of decreasing laser power gradually is more effective than the optimized strategy of increasing the time interval between layers in maintaining the stability of the molten pool. The integrated optimized strategy of parabolic-shape laser power decreasing and time interval of 5 s is the most effective method to reduce the heat accumulation in the DMD of thin-walled parts. The thin-walled parts with an optimized deposition process have a more uniform width, finer microstructure, and higher microhardness. This work provides theoretical guidance for reducing the heat accumulation during DMD thin-walled parts and is beneficial to improving the uniformity of mechanical properties of thin-walled parts.

Enhanced Optical Response of Zinc-Doped Tin Disulfide Layered Crystals Grown with the Chemical Vapor Transport Method.

Tin disulfide (SnS2) is a promising semiconductor for use in nanoelectronics and optoelectronics. Doping plays an essential role in SnS2 applications, because it can increase the functionality of SnS2 by tuning its original properties. In this study, the effect of zinc (Zn) doping on the photoelectric characteristics of SnS2 crystals was explored. The chemical vapor transport method was adopted to grow pristine and Zn-doped SnS2 crystals. Scanning electron microscopy images indicated that the grown SnS2 crystals were layered materials. The ratio of the normalized photocurrent of the Zn-doped specimen to that of the pristine specimen increased with an increasing illumination frequency, reaching approximately five at 104 Hz. Time-resolved photocurrent measurements revealed that the Zn-doped specimen had shorter rise and fall times and a higher current amplitude than the pristine specimen. The photoresponsivity of the specimens increased with an increasing bias voltage or decreasing laser power. The Zn-doped SnS2 crystals had 7.18 and 3.44 times higher photoresponsivity, respectively, than the pristine crystals at a bias voltage of 20 V and a laser power of 4 × 10−8 W. The experimental results of this study indicate that Zn doping markedly enhances the optical response of SnS2 layered crystals.

Effect of processing parameters on formability, microstructure, and micro-hardness of a novel laser additive manufactured Ti-6.38Al-3.87V-2.43Mo alloy

A novel Ti-6.38Al-3.87V-2.43Mo alloy was designed with a cluster formula of 12[Al-Ti12] (V0.75Mo0.25Ti2)+4[Al-Ti12](Al3) by replacing Ti with Mo/V on the basis of the Ti-Al congruent alloy. The effects of laser power and scanning speed on the molten pool size, surface roughness, relative density, microstructure, and micro-hardness of single-track and bulk Ti-6.38Al-3.87V-2.43Mo samples prepared via laser additive manufacturing (LAM) were investigated. The results show that processing parameters significantly affect the formability, microstructure, and micro-hardness of the alloy. With decreasing laser power from 1,900 W to 1,000 W, the relative density is decreased from 99.86% to 90.91% due to the increase of lack-of-fusion; however, with increasing scanning speed, the relative density does not change significantly, but exceeds 99%. In particular, Ti-6.38Al-3.87V-2.43Mo samples of single-track and bulk exhibit a good formability under an input laser power of 1,900 W and a scanning speed of 8 mm·s-1, and display the lowest surface roughness (Ra=13.33 µm) and the highest relative density (99.86%). Besides, the microstructure of LAM Ti-6.38Al-3.87V-2.43Mo alloy coarsens with increasing laser power or decreasing scanning speed due to the greater input energy reducing the cooling rate. The coarsening of the microstructure decreases the microhardness of the alloy.

Effect of hatch spacing and laser power on microstructure, texture, and thermomechanical properties of laser powder bed fusion (L-PBF) additively manufactured NiTi

This study systematically evaluates the effects of laser powder bed fusion additive manufacturing (L-PBF-AM) parameters (hatch spacing and laser power) on the thermomechanical behavior and microstructure of Ni50.8Ti49.2 shape memory alloy. The samples were fabricated with hatch spacings from 40 to 240 µm and laser powers of 50 and 100 W at a constant scanning speed of 125 mm/s, resulting in parts with volumetric energy density levels from 55 to 666 J/mm3 and two sets of linear energy densities of 0.4 and 0.8 J/mm. The results showed a reduced melt pool size and discontinuity of scan tracks with decreased laser power. Additionally, the porosity level was increased with larger hatch spacing and lower laser power. More notably, the transformation temperatures increased, and the critical stress, recoverable strain, and functional stability of samples improved with lower hatch spacing, where the recovery ratio of up to 90% was observed, regardless of the employed laser power. This study also discussed the relationship between the fabrication process and texture formation in the L-PBF-AM process. The advantage of L-PBF-AM was revealed in tailoring the microstructure from highly textured samples in [111] or [001] direction when hatch spacing lower than laser beam focused was employed, to the appearance of equiaxed solidification front with island grains and random orientations.

Comparative study of filament-fed and blown powder-based laser additive manufacturing for transparent magnesium aluminate spinel ceramics

Magnesium aluminate spinel is of great interest as a transparent ceramic for its excellent mechanical properties and excellent optical transmittance. Additive manufacturing of this desirable material presents several benefits over traditional manufacturing methods, including reduced fabrication time and cost and the potential to fabricate structures with complex geometries and internal cooling networks. Despite the many benefits, the challenges hindering this technology must be overcome. A primary challenge with powder-based laser additive manufacturing of transparent ceramics is a trade-off between densification and cracking. The fabrication of transparent ceramics requires nearly full densification since pores act as light scattering centers. Even relatively small percentages of porosity render ceramics translucent or opaque. Previous studies on powder-based laser direct deposition of spinel ceramics have shown that densification to transparency is possible with high-laser power deposition. While high-laser powers are beneficial for densification, it also produces high thermal gradients that result in significant crack formation. Cracks hinder mechanical properties and transparency, limiting possible applications. Thus, we propose a filament-based deposition strategy to reduce laser power requirements. Filament-fed laser direct deposition, instead of blown powder, dramatically reduced the amount of gas porosity within the melt. Hence, highly densified, transparent, spinel ceramics were fabricated. Through decreased laser power requirements for high densification, cracking was largely reduced. This paper provides a comprehensive comparison between filament- and powder-based laser direct deposition by analyzing important sample characteristics, including porosity, cracking, grain size, and their controlling mechanisms. This paper also presents a laser direct deposition and postprocessing method to manufacture predensified spinel filaments.

Using femtosecond laser pulses to study the nonlinear optical properties of rhodamine 6G dissolved in water

Using the Z- scan method, we studied the nonlinear absorption coefficient of rhodamine 6G dissolved in water. With laser pulses of 100 fs, the nonlinear absorption coefficient was measured at different excitation wavelengths and incident powers for both water and R6G. Water behavior showed saturable absorption (SA) at high power (>0.8 W) but at low laser power (<0.8 W) does not exhibit any nonlinearity whatever of the wavelength of excitation. At high laser power, the nonlinear absorption coefficient of the water increases as the wavelength decreases. A transition from saturable absorption to reverse saturable absorption (RSA) was observed when R6G was added to the water. In the case of R6G solution, the nonlinear absorption coefficient was found to be sensitive to both excitation wavelength and power. The two photon absorption cross-section was obtained from the nonlinear absorption coefficient of rhodamine 6G solution and was found to increase with increasing excitation wavelength while increasing with decreasing laser power. The nonlinear absorption coefficient β and nonlinear refractive index n2 of rhodamine 6G solution were found to be concentration dependent. Based on its RSA behaviour, the optical limiting of rhodamine 6G solution was measured and found to be concentration dependent. The higher concentration of rhodamine 6G solution has better optical limiting characteristics.

Numerical Analysis of Microstructure Anomalies during Laser Welding Nickel-Based Single-Crystal Superalloy Part III: Amelioration of Solidification Behavior

The contribution of crystallography-dependent metallurgical factors, such as supersaturation of liquid aluminum and minimum dendrite tip undercooling, to solidification behavior and microstructure development is numerically analyzed during Ni-Cr-Al ternary single-crystal superalloy molten pool solidification to better understand thermodynamic and kinetic driving forces behind solidification cracking resistance. The variation of supersaturation of liquid aluminum and minimum dendrite tip undercooling with location of solid/liquid interface is symmetrically consistent in (001)/[100] welding configuration. By comparison, the variation is asymmetrically consistent in (001)/[110] welding configuration. The different distribution is attributed to growth crystallography and dendrite selection. Significant increase of supersaturation of liquid aluminum and dendrite tip undercooling from [010] dendrite growth region to [100] dendrite growth region preferentially aggravates microstructure development as result of nucleation and growth of stray grain formation with the same heat input on each half of the weld pool in (001)/[110] welding configuration. High heat input (both increasing laser power and decreasing welding speed) exacerbates supersaturation of liquid aluminum and dendrite tip undercooling by faster diffusion to incur stray grain formation with severity of contributing thermometallurgical factors for susceptibility to solidification cracking, while low heat input (both decreasing laser power and increasing welding speed) ameliorates microstructure development and increases resistance to solidification cracking. Weld microstructure of optimum welding conditions, such as combination of low heat input and (001)/[100] welding configuration, is less susceptible to solidification cracking to suppress asymmetrical microstructure development and improve weld integrity potential rather than insidious welding conditions, such as combination of high heat input and (001)/[110] welding configuration. Severer supersaturation of liquid aluminum and wider dendrite tip undercooling occur in the [100] dendrite region as consequence of alloying enrichment, while smaller supersaturation of liquid aluminum and narrower dendrite tip undercooling occur in the [001] dendrite region as consequence of alloying depletion to spontaneously facilitate epitaxial growth of single-crystal essential. Symmetrical (001)/[100] welding configuration decreases growth kinetics of dendrite tip with smaller overall supersaturation of liquid aluminum and dendrite tip undercooling than that of asymmetrical (001)/[110] welding configuration regardless of combination of laser power and welding speed. Mitigation of supersaturation of liquid aluminum and dendrite tip undercooling simultaneously alleviate crack-susceptible microstructure development and solidification cracking. Additionally, the appropriate mechanism of solidification cracking resistance improvement through modification of crystallography-dependent supersaturation and undercooling of dendrite tip is proposed. Calculation analyses are sufficiently explained by experiment results in a reasonable way. The additional purpose of this theoretical analysis is to evaluate solidification cracking susceptibility of similar nickel-based or iron-based single-crystal superalloys.

Numerical Analysis of Stray Grain Formation during Laser Welding Nickel-Based Single-Crystal Superalloy Part III: Crystallography-Dependent Solidification Behavior

The solidification temperature range was numerically analyzed to optimize nonequilibrium solidification behavior during ternary Ni-Cr-Al nickel-based single-crystal superalloy weld pool solidification with variation of laser welding conditions (either heat input or welding configuration). The distribution of solidification temperature range along the fusion boundary is beneficially symmetrical about the weld pool centerline in the (001)/[100] welding configuration. The distribution of solidification temperature range along the fusion boundary is detrimentally asymmetrical about the weld pool centerline in the (001)/[110] welding configuration. The stray grain formation and solidification cracking are preferentially confined to [100] dendrite growth region. [001] epitaxial growth region with columnar dendrite morphology is favored at the expense of undesirable [100] growth region with equiaxed dendrite morphology to facilitate essential single-crystal solidification with considerable reduction of heat input. The smaller heat input is used, the narrower solidification temperature range is thermodynamically promoted to reduce nucleation and growth of stray grain formation with decrease of constitutional undercooling ahead of dendrite tip and mitigate thermo-metallurgical factors for morphology instability and microstructure anomalies. Potential low heat input(both decreasing laser power and increasing welding speed) with (001)/[100] welding configuration decreases solidification temperature range to significantly minimize columnar/equiaxed transition (CET) and stray grain formation, and improve resistance to solidification cracking through microstructure control. On both sides of weld pool are imposed by the same heat input, while the solidification temperature range along the fusion boundary inside of [100] dendrite growth region on the right part of the weld pool is spontaneously wider than that of [010] dendrite growth region on the left part to increase solidification cracking susceptibility in the (001)/[110] welding configuration. Furthermore, another mechanism of solidification cracking as consequence of severe solidification behavior and anomalous microstructure with asymmetrical crystallographic orientation is therefore proposed. The theoretical predictions are well verified by experiment results. The useful and satisfactory numerical modeling is also available for other single-crystal superalloys during successful laser repair process without stray grain formation.