Pub Date : 2026-02-01Epub Date: 2025-12-15DOI: 10.1016/j.jmatprotec.2025.119185
Arvind Chouhan , Lutz Mädler , Nils Ellendt
Multi-material laser powder bed fusion (PBF-LB/M) enables the fabrication of components with tailored properties for advanced applications. However, large differences in thermophysical behavior between alloys such as Cu and SS316L introduce processing challenges, including lack of fusion, porosity, and thermal cracking at material interfaces. In this study, a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) framework with a Volume of Fluid (VOF) methodology is developed to investigate melt pool dynamics, interfacial mixing, and solidification in laser powder bed fusion of Cu-SS316L. The model accounts for temperature and composition dependent thermophysical properties, diffusion-driven species transport, and laser–material interaction through a ray-tracing approach. Experimental validation is conducted to support the numerical findings. Simulations reveal that high Cu content results in smaller melt pools and lack of fusion defects due to Cu's high reflectivity and thermal diffusivity, whereas SS316L rich regions produce larger melt pools, reducing fusion defects but increasing keyhole porosity risk. At the Cu-SS316L interface, asymmetric melting and rapid solidification on the Cu side limit mixing, forming sharp diffusion boundaries. Steep thermal gradients across the interface induce differential thermal expansion, leading to thermal crack formation, particularly under high energy input. To mitigate such defects, a material grading strategy is proposed to smooth thermal gradients and reduce residual stresses. The proposed numerical framework offers critical insights into the mixing mechanisms at dissimilar interfaces for optimizing the multi-material PBF-LB/M process.
{"title":"Modeling composition-dependent melt dynamics and defect formation in multi-material additive manufacturing","authors":"Arvind Chouhan , Lutz Mädler , Nils Ellendt","doi":"10.1016/j.jmatprotec.2025.119185","DOIUrl":"10.1016/j.jmatprotec.2025.119185","url":null,"abstract":"<div><div>Multi-material laser powder bed fusion (PBF-LB/M) enables the fabrication of components with tailored properties for advanced applications. However, large differences in thermophysical behavior between alloys such as Cu and SS316L introduce processing challenges, including lack of fusion, porosity, and thermal cracking at material interfaces. In this study, a coupled Discrete Element Method-Computational Fluid Dynamics (DEM-CFD) framework with a Volume of Fluid (VOF) methodology is developed to investigate melt pool dynamics, interfacial mixing, and solidification in laser powder bed fusion of Cu-SS316L. The model accounts for temperature and composition dependent thermophysical properties, diffusion-driven species transport, and laser–material interaction through a ray-tracing approach. Experimental validation is conducted to support the numerical findings. Simulations reveal that high Cu content results in smaller melt pools and lack of fusion defects due to Cu's high reflectivity and thermal diffusivity, whereas SS316L rich regions produce larger melt pools, reducing fusion defects but increasing keyhole porosity risk. At the Cu-SS316L interface, asymmetric melting and rapid solidification on the Cu side limit mixing, forming sharp diffusion boundaries. Steep thermal gradients across the interface induce differential thermal expansion, leading to thermal crack formation, particularly under high energy input. To mitigate such defects, a material grading strategy is proposed to smooth thermal gradients and reduce residual stresses. The proposed numerical framework offers critical insights into the mixing mechanisms at dissimilar interfaces for optimizing the multi-material PBF-LB/M process.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119185"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-31DOI: 10.1016/j.jmatprotec.2025.119192
Hui Wang, Jianjun Wu, Zekun Yang, Long Liu, Mengyuan Wang
Wrinkling instability of spatial tubes caused by inappropriate combinations of process parameters during free bending forming (FBF) severely restricts the forming stability. The correlation mechanism between the critical wrinkling loads (CWL) under bending-torsion coupled and the process window remains unclear, which makes it difficult to effectively control wrinkling defects of spatial tubes FBF. This study establishes a critical wrinkling analysis model under bending-torsion coupled (CWAM-CBT) of spatial tubes to calculate CWL. Based on the energy physical meaning of yielding and combined with the quadratic model of bending-torsion buckling (QM-BTB), approximate upper and lower bounds of buckling strength are proposed as the wrinkling criterion. The effects of load ratio, radius-to-thickness ratio, and tube material properties on the CWL and buckling strength are investigated. The validity of the analysis model is verified through a simplified finite element model. By combining the analysis model with finite element simulation of spatial tubes FBF, the critical wrinkling loading path of spatial tubes is constructed according to the relationship between process parameters and load ratios in the stable forming stage. The critical wrinkling loading path divides the process window into three zones, namely the wrinkling zone, the critical wrinkling zone, and the without wrinkling zone. Experiments on spatial tubes FBF have verified that the critical wrinkling loading path can accurately predict the wrinkling behavior under different process parameters, while further validating the effectiveness of the analytical model. This work enhances the in-depth understanding of the bending-torsion coupled wrinkling mechanism during spatial tubes FBF, thereby providing an effective method for the process optimization of complex spatial tube components.
{"title":"Critical wrinkling analysis under bending-torsion coupled of spatial tubes during free bending forming","authors":"Hui Wang, Jianjun Wu, Zekun Yang, Long Liu, Mengyuan Wang","doi":"10.1016/j.jmatprotec.2025.119192","DOIUrl":"10.1016/j.jmatprotec.2025.119192","url":null,"abstract":"<div><div>Wrinkling instability of spatial tubes caused by inappropriate combinations of process parameters during free bending forming (FBF) severely restricts the forming stability. The correlation mechanism between the critical wrinkling loads (CWL) under bending-torsion coupled and the process window remains unclear, which makes it difficult to effectively control wrinkling defects of spatial tubes FBF. This study establishes a critical wrinkling analysis model under bending-torsion coupled (CWAM-CBT) of spatial tubes to calculate CWL. Based on the energy physical meaning of yielding and combined with the quadratic model of bending-torsion buckling (QM-BTB), approximate upper and lower bounds of buckling strength are proposed as the wrinkling criterion. The effects of load ratio, radius-to-thickness ratio, and tube material properties on the CWL and buckling strength are investigated. The validity of the analysis model is verified through a simplified finite element model. By combining the analysis model with finite element simulation of spatial tubes FBF, the critical wrinkling loading path of spatial tubes is constructed according to the relationship between process parameters and load ratios in the stable forming stage. The critical wrinkling loading path divides the process window into three zones, namely the wrinkling zone, the critical wrinkling zone, and the without wrinkling zone. Experiments on spatial tubes FBF have verified that the critical wrinkling loading path can accurately predict the wrinkling behavior under different process parameters, while further validating the effectiveness of the analytical model. This work enhances the in-depth understanding of the bending-torsion coupled wrinkling mechanism during spatial tubes FBF, thereby providing an effective method for the process optimization of complex spatial tube components.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119192"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-10DOI: 10.1016/j.jmatprotec.2025.119182
Zhiyuan Xu, Jinzhe Li, Kuangji Zhu, Yansong Zhang
This study investigates the fundamental effects of electric current treatment (ECT) on the microstructural evolution and functional performance of NiTi shape memory alloy (SMA) ultrasonic spot welding (USW) joints. Under optimal parameters (100 A, 2 min), the joints exhibit the highest recovery ratio during cyclic tensile testing. The enhancement arises from the intrinsic role of the electric current in regulating material performance: Electric current treatment accelerates elemental diffusion and promotes the formation of a high density of fine Ni4Ti3 precipitates at the interface, while the electron wind force lowers the energy barrier for 1/2[111] dislocation slip, generating high-density wavy dislocations. Together, these mechanisms demonstrate controlled microstructural tailoring that directly links processing conditions to dislocation dynamics, precipitate evolution, and functional stability. These findings reveal a fundamental materials-processing strategy for actively controlling microstructure and superelastic performance in NiTi SMAs, advancing understanding beyond conventional thermal or mechanical treatments.
研究了电流处理（ECT）对NiTi形状记忆合金（SMA）超声点焊（USW）接头组织演变和功能性能的影响。在最优参数（100 A, 2 min）下，节理在循环拉伸试验中恢复率最高。这种增强源于电流对材料性能的内在调节作用：电流处理加速了元素的扩散，促进了界面处高密度的Ni4Ti3细晶析出相的形成，而电子风作用力降低了1/2[111]位错滑移的能垒，产生高密度的波浪形位错。总之，这些机制证明了受控的微观结构剪裁，将加工条件与位错动力学、沉淀演化和功能稳定性直接联系起来。这些发现揭示了一种基本的材料加工策略，可以主动控制NiTi sma的微观结构和超弹性性能，超越传统的热处理或机械处理。
{"title":"Enhancing strain recovery ratio of NiTi ultrasonic spot welding joints via electric current treatment induced dislocations and precipitates","authors":"Zhiyuan Xu, Jinzhe Li, Kuangji Zhu, Yansong Zhang","doi":"10.1016/j.jmatprotec.2025.119182","DOIUrl":"10.1016/j.jmatprotec.2025.119182","url":null,"abstract":"<div><div>This study investigates the fundamental effects of electric current treatment (ECT) on the microstructural evolution and functional performance of NiTi shape memory alloy (SMA) ultrasonic spot welding (USW) joints. Under optimal parameters (100 A, 2 min), the joints exhibit the highest recovery ratio during cyclic tensile testing. The enhancement arises from the intrinsic role of the electric current in regulating material performance: Electric current treatment accelerates elemental diffusion and promotes the formation of a high density of fine Ni<sub>4</sub>Ti<sub>3</sub> precipitates at the interface, while the electron wind force lowers the energy barrier for 1/2[111] dislocation slip, generating high-density wavy dislocations. Together, these mechanisms demonstrate controlled microstructural tailoring that directly links processing conditions to dislocation dynamics, precipitate evolution, and functional stability. These findings reveal a fundamental materials-processing strategy for actively controlling microstructure and superelastic performance in NiTi SMAs, advancing understanding beyond conventional thermal or mechanical treatments.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119182"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-16DOI: 10.1016/j.jmatprotec.2025.119187
Jiayuan Dong , Sota Sugihara , Kafumi Fujiwara , Rongyan Sun , Yuji Ohkubo , Junsha Wang , Tadatomo Suga , Kazuya Yamamura
Due to its extreme hardness and chemical stability, diamond poses significant challenges for traditional machining processes. Plasma-assisted polishing (PAP) is a recently developed technique that integrates chemically active species from plasma with mechanical polishing, offering great potential for highly efficient and precise surface finishing of diamond materials. In this study, the polishing characteristics of silicon and silica plates were comprehensively investigated. The results confirmed the superiority of the silicon plate, which produced a smoother diamond surface and achieved a higher material removal rate (MRR) during PAP. To clarify the origin of this difference, the synergistic role of plasma irradiation was examined, as plasma is known to significantly enhance both the MRR and surface quality of diamond. Accordingly, X-ray photoelectron spectroscopy (XPS) measurements combined with density functional theory (DFT) calculations were conducted to gain deeper insights into the underlying mechanisms. The analyses revealed that both the polishing plate material and plasma irradiation play crucial roles in the PAP process. The higher chemical reactivity of silicon promotes bond formation at the tribological interface, thereby facilitating carbon removal. Meanwhile, oxygen radicals generated by plasma participate in interfacial reactions by oxidizing both the diamond and the polishing plate surface, as well as promoting the formation of oxygen-bridge bonds. This process enhances the diamond removal rate but simultaneously accelerates wear of the polishing plate surface. To further evaluate this effect, a long-duration polishing experiment was performed to investigate plate wear. The results showed that as wear progresses, the plate surface becomes smoother, leading to a decline in both polishing accuracy and the MRR of the diamond substrate. To counteract this effect, laser dressing was introduced to restore and sustain surface roughness, and its effectiveness was experimentally confirmed. Finally, PAP was applied to a 2-inch polycrystalline diamond substrate, achieving a grain-boundary step-free surface with a surface roughness (Sa) of approximately 0.3 nm. These findings provide practical guidance for the ultra-precision machining of diamond, deepen the understanding of coupled chemical–mechanical interactions at the tribological interface, and support the advancement of diamond-based components in semiconductor applications.
{"title":"Plasma-assisted polishing with silicon and silica plates: Comparison of interaction mechanism and achievement of atomically flat surfaces on single- and polycrystalline diamond","authors":"Jiayuan Dong , Sota Sugihara , Kafumi Fujiwara , Rongyan Sun , Yuji Ohkubo , Junsha Wang , Tadatomo Suga , Kazuya Yamamura","doi":"10.1016/j.jmatprotec.2025.119187","DOIUrl":"10.1016/j.jmatprotec.2025.119187","url":null,"abstract":"<div><div>Due to its extreme hardness and chemical stability, diamond poses significant challenges for traditional machining processes. Plasma-assisted polishing (PAP) is a recently developed technique that integrates chemically active species from plasma with mechanical polishing, offering great potential for highly efficient and precise surface finishing of diamond materials. In this study, the polishing characteristics of silicon and silica plates were comprehensively investigated. The results confirmed the superiority of the silicon plate, which produced a smoother diamond surface and achieved a higher material removal rate (MRR) during PAP. To clarify the origin of this difference, the synergistic role of plasma irradiation was examined, as plasma is known to significantly enhance both the MRR and surface quality of diamond. Accordingly, X-ray photoelectron spectroscopy (XPS) measurements combined with density functional theory (DFT) calculations were conducted to gain deeper insights into the underlying mechanisms. The analyses revealed that both the polishing plate material and plasma irradiation play crucial roles in the PAP process. The higher chemical reactivity of silicon promotes bond formation at the tribological interface, thereby facilitating carbon removal. Meanwhile, oxygen radicals generated by plasma participate in interfacial reactions by oxidizing both the diamond and the polishing plate surface, as well as promoting the formation of oxygen-bridge bonds. This process enhances the diamond removal rate but simultaneously accelerates wear of the polishing plate surface. To further evaluate this effect, a long-duration polishing experiment was performed to investigate plate wear. The results showed that as wear progresses, the plate surface becomes smoother, leading to a decline in both polishing accuracy and the MRR of the diamond substrate. To counteract this effect, laser dressing was introduced to restore and sustain surface roughness, and its effectiveness was experimentally confirmed. Finally, PAP was applied to a 2-inch polycrystalline diamond substrate, achieving a grain-boundary step-free surface with a surface roughness (<em>S</em>a) of approximately 0.3 nm. These findings provide practical guidance for the ultra-precision machining of diamond, deepen the understanding of coupled chemical–mechanical interactions at the tribological interface, and support the advancement of diamond-based components in semiconductor applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119187"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-03DOI: 10.1016/j.jmatprotec.2025.119165
Huihui Nie , Yangyang Yang , Jinyi Li , Haoran Guo , Wentao Fan , Hongsheng Chen , Jun Zhou , Wenxian Wang
In this work, a novel type of Al/Cu composite tubes were successfully produced by strong staggered spinning with good surface quality, and the effect of thickness reductions on the microstructure and bonding mechanism of interface and the texture evolution of component layers. The results show that the original intermetallics layer in base material (BM) cracks and twists during spinning, and the contact area between fresh Al and Cu increases, resulting in a new diffusion layer containing AlCu, Al2Cu3 and Al4Cu9 phases from Al to Cu matrix, which presents a hardness between Cu and Al and facilitates stress transfer and deformation coordination. Cu atoms show a higher diffusion rate partly because grains, fragments or atomic clusters of Cu are pushed or sheared into Al and partly because abundant GBs and dislocations in Al provide excellent channels for the rapid diffusion of Cu atoms. With the increase of thickness reduction, Cu grains are elongated in S25 % and kinking of deformation zones are formed in S70 %, and the corresponding grain size decreases from 1.45μm to 0.98μm with a {111} < 112 > shear texture. Besides, Cu grains with orientation of < 001 > //AD are more prone to deformation and gradually change their orientation to < 111 > //AD, causing a growth of texture intensity in S70 %. The extent of grain refinement of Al near Cu is larger than that of Al away from the interface owing to the shear effect of interface, and the latter ones change from elongated grains to equiaxial grains as the increase of thickness reduction because of the extensive DRX, resulting Cube {100} < 001 > texture with the highest intensity of 14.1 among the three tubes. Interface delamination is not observed during tensile tests, although the interface microstructure varies. The well-bonded interface, refinement strengthening and work hardening enhance the UTS of S70 % to 172.89 MPa, increasing by 56.7 % compared with that of BM (110.34 MPa).
{"title":"Effect of thickness reduction of strong staggered spinning on the interface microstructure, texture evolution and mechanical properties of Al/Cu composite tubes","authors":"Huihui Nie , Yangyang Yang , Jinyi Li , Haoran Guo , Wentao Fan , Hongsheng Chen , Jun Zhou , Wenxian Wang","doi":"10.1016/j.jmatprotec.2025.119165","DOIUrl":"10.1016/j.jmatprotec.2025.119165","url":null,"abstract":"<div><div>In this work, a novel type of Al/Cu composite tubes were successfully produced by strong staggered spinning with good surface quality, and the effect of thickness reductions on the microstructure and bonding mechanism of interface and the texture evolution of component layers. The results show that the original intermetallics layer in base material (BM) cracks and twists during spinning, and the contact area between fresh Al and Cu increases, resulting in a new diffusion layer containing AlCu, Al<sub>2</sub>Cu<sub>3</sub> and Al<sub>4</sub>Cu<sub>9</sub> phases from Al to Cu matrix, which presents a hardness between Cu and Al and facilitates stress transfer and deformation coordination. Cu atoms show a higher diffusion rate partly because grains, fragments or atomic clusters of Cu are pushed or sheared into Al and partly because abundant GBs and dislocations in Al provide excellent channels for the rapid diffusion of Cu atoms. With the increase of thickness reduction, Cu grains are elongated in S25 % and kinking of deformation zones are formed in S70 %, and the corresponding grain size decreases from 1.45μm to 0.98μm with a {111} < 112 > shear texture. Besides, Cu grains with orientation of < 001 > //AD are more prone to deformation and gradually change their orientation to < 111 > //AD, causing a growth of texture intensity in S70 %. The extent of grain refinement of Al near Cu is larger than that of Al away from the interface owing to the shear effect of interface, and the latter ones change from elongated grains to equiaxial grains as the increase of thickness reduction because of the extensive DRX, resulting Cube {100} < 001 > texture with the highest intensity of 14.1 among the three tubes. Interface delamination is not observed during tensile tests, although the interface microstructure varies. The well-bonded interface, refinement strengthening and work hardening enhance the UTS of S70 % to 172.89 MPa, increasing by 56.7 % compared with that of BM (110.34 MPa).</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119165"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145665537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2026-01-02DOI: 10.1016/j.jmatprotec.2026.119196
Haipeng Liao , Peng Chi , Lina You , Jianliang Hu , Liang Cheng , Qin Zhang , Xiangmiao Wu , Lianyong Xu , Zhenmin Wang
To overcome the adverse effects of the uneven composition of the molten pool and the poor growth of columnar crystals caused by rapid cooling underwater during underwater welding on the corrosion performance of underwater welds, this study innovatively proposed a double pulsed current (DPC) waveform modulation technology. The influence of different DPC waveforms on the microstructure evolution and corrosion resistance of local dry underwater welded 304 stainless steel (SUS304) was systematically studied. The results show that DPC induced the periodic oscillation of arc energy distribution, which achieved the stirring effect on the underwater molten pool, thereby refining the grain structure by maximum 54.6 %, increasing the ferrite content by 43.2 % and making it uniformly distributed on the austenite matrix. It promoted the transformation of ferrite morphology from skeleton to lath, and enhanced the uniformity of the molten pool composition. With the decrease of the weak pulse peak current, the stirring effect exhibited a trend of first enhancing and then weakening. The corrosion failure mode of the SUS304 underwater weldment was pitting corrosion. The fine grain structure and higher ferrite content brought by DPC facilitated to form a stable passivation film structure, increasing its thickness by 173.1 %, thereby improving the corrosion resistance of underwater weldment. This work provides a flexible solution and solid foundation for underwater welding quality optimizing of austenitic stainless steel, which promote the application of underwater welding technology in the construction and repair of large underwater structures.
{"title":"The mechanism of double pulsed current on improving microstructure and enhancing corrosion resistance of underwater welded 304 stainless steel","authors":"Haipeng Liao , Peng Chi , Lina You , Jianliang Hu , Liang Cheng , Qin Zhang , Xiangmiao Wu , Lianyong Xu , Zhenmin Wang","doi":"10.1016/j.jmatprotec.2026.119196","DOIUrl":"10.1016/j.jmatprotec.2026.119196","url":null,"abstract":"<div><div>To overcome the adverse effects of the uneven composition of the molten pool and the poor growth of columnar crystals caused by rapid cooling underwater during underwater welding on the corrosion performance of underwater welds, this study innovatively proposed a double pulsed current (DPC) waveform modulation technology. The influence of different DPC waveforms on the microstructure evolution and corrosion resistance of local dry underwater welded 304 stainless steel (SUS304) was systematically studied. The results show that DPC induced the periodic oscillation of arc energy distribution, which achieved the stirring effect on the underwater molten pool, thereby refining the grain structure by maximum 54.6 %, increasing the ferrite content by 43.2 % and making it uniformly distributed on the austenite matrix. It promoted the transformation of ferrite morphology from skeleton to lath, and enhanced the uniformity of the molten pool composition. With the decrease of the weak pulse peak current, the stirring effect exhibited a trend of first enhancing and then weakening. The corrosion failure mode of the SUS304 underwater weldment was pitting corrosion. The fine grain structure and higher ferrite content brought by DPC facilitated to form a stable passivation film structure, increasing its thickness by 173.1 %, thereby improving the corrosion resistance of underwater weldment. This work provides a flexible solution and solid foundation for underwater welding quality optimizing of austenitic stainless steel, which promote the application of underwater welding technology in the construction and repair of large underwater structures.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119196"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The high-temperature performance of current additively manufactured IN 718 alloy is critically limited by synergistic effects of surface-topography-induced stress concentrators, and subcritical porosity, particularly the thermal softening of the γ″ phase and its heterogeneous distribution within grains at 650 °C. Here, we propose a laser polishing treatment strategy that reconstructs both surface and sub-surface architecture of LPBF Inconel 718 alloy. This approach significantly reduces surface roughness from Ra ≥ 10 µm to Ra ≤ 1 µm, eliminates near-surface porosity by up to 65.7 %, and forms a refined, uniform nanometric dislocation cell. High-temperature tensile tests demonstrate plasticity performance nearly doubled at 650 °C with only 3 % yield strength loss. The detailed fractographic and microstructural analyses have confirmed that the enhanced plasticity originates from: (1) stabilized dislocation cell structures that homogenize stress distribution and suppress grain boundary cracking, (2) elimination of columnar grain morphology through dynamic recrystallization, and (3) delayed crack initiation and propagation between 550 and 650 ℃ due to dislocation cell structural confinement. Laser polishing produces a near-surface dislocation-cell structure engineering emerges as a transformative post-processing strategy, enabling additively manufactured IN718 alloy to overcome intrinsic high-temperature limitations through dislocation cell, thus redefining the strength-ductility paradigm at elevated temperatures.
{"title":"Laser polishing of LPBF IN718 forms dislocation cells and enhances high temperature ductility","authors":"Qirui Zhang , Xing Li , Mingze Xin , Yingchun Guan","doi":"10.1016/j.jmatprotec.2025.119175","DOIUrl":"10.1016/j.jmatprotec.2025.119175","url":null,"abstract":"<div><div>The high-temperature performance of current additively manufactured IN 718 alloy is critically limited by synergistic effects of surface-topography-induced stress concentrators, and subcritical porosity, particularly the thermal softening of the γ″ phase and its heterogeneous distribution within grains at 650 °C. Here, we propose a laser polishing treatment strategy that reconstructs both surface and sub-surface architecture of LPBF Inconel 718 alloy. This approach significantly reduces surface roughness from Ra ≥ 10 µm to Ra ≤ 1 µm, eliminates near-surface porosity by up to 65.7 %, and forms a refined, uniform nanometric dislocation cell. High-temperature tensile tests demonstrate plasticity performance nearly doubled at 650 °C with only 3 % yield strength loss. The detailed fractographic and microstructural analyses have confirmed that the enhanced plasticity originates from: (1) stabilized dislocation cell structures that homogenize stress distribution and suppress grain boundary cracking, (2) elimination of columnar grain morphology through dynamic recrystallization, and (3) delayed crack initiation and propagation between 550 and 650 ℃ due to dislocation cell structural confinement. Laser polishing produces a near-surface dislocation-cell structure engineering emerges as a transformative post-processing strategy, enabling additively manufactured IN718 alloy to overcome intrinsic high-temperature limitations through dislocation cell, thus redefining the strength-ductility paradigm at elevated temperatures.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119175"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liquation cracking remains a critical challenge in the repair of precipitation-strengthened Ni-based superalloys, and convenient pre-weld heat treatment processes along with corresponding microstructural design principles are still underdeveloped. This study systematically investigates the influence of various pre-weld heat treatment processes on liquation cracking susceptibility in K4951 superalloy using tungsten inert gas welding, Gleeble thermomechanical simulation, and multi-scale characterization. The results provide a general framework correlating grain boundary orientation, precipitate morphology, and segregation behavior with liquation crack initiation. The critical grain boundary misorientation for liquation crack initiation is approximately 13°, with susceptibility reaching its maximum within the 20°–50° range, which stems from the stabilization of the intergranular liquid film at the coalescence temperature due to high grain-boundary energy, thereby leading to the highest cracking susceptibility. An optimized treatment combining solution and short-time aging effectively reduces hardness, tailors γ′ morphology, and alleviates Nb/Mo segregation, thereby suppressing the constitutional liquation of MC carbides and M3B2 borides. These findings demonstrate that the pre-weld heat treatment process represents a viable approach for designing microstructures with enhanced resistance to liquation cracking. The revealed mechanisms and strategies offer transferable guidance for developing crack-resistant repair procedures for various precipitation-strengthened Ni-based superalloys.
{"title":"Generic strategies for suppressing liquation cracking through microstructural design in precipitation-strengthened Ni-based superalloys","authors":"Qingquan Chu , Shiyang Wang , Renliang Peng , Zhendong Wu , Xingyu Hou , Hongyu Zhang , Hongwei Zhang , Yuan Sun , Yizhou Zhou","doi":"10.1016/j.jmatprotec.2025.119188","DOIUrl":"10.1016/j.jmatprotec.2025.119188","url":null,"abstract":"<div><div>Liquation cracking remains a critical challenge in the repair of precipitation-strengthened Ni-based superalloys, and convenient pre-weld heat treatment processes along with corresponding microstructural design principles are still underdeveloped. This study systematically investigates the influence of various pre-weld heat treatment processes on liquation cracking susceptibility in K4951 superalloy using tungsten inert gas welding, Gleeble thermomechanical simulation, and multi-scale characterization. The results provide a general framework correlating grain boundary orientation, precipitate morphology, and segregation behavior with liquation crack initiation. The critical grain boundary misorientation for liquation crack initiation is approximately 13°, with susceptibility reaching its maximum within the 20°–50° range, which stems from the stabilization of the intergranular liquid film at the coalescence temperature due to high grain-boundary energy, thereby leading to the highest cracking susceptibility. An optimized treatment combining solution and short-time aging effectively reduces hardness, tailors γ′ morphology, and alleviates Nb/Mo segregation, thereby suppressing the constitutional liquation of MC carbides and M<sub>3</sub>B<sub>2</sub> borides. These findings demonstrate that the pre-weld heat treatment process represents a viable approach for designing microstructures with enhanced resistance to liquation cracking. The revealed mechanisms and strategies offer transferable guidance for developing crack-resistant repair procedures for various precipitation-strengthened Ni-based superalloys.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119188"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145837151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-12-11DOI: 10.1016/j.jmatprotec.2025.119183
Yi Zhou , Jun Luo , Lin Su , Lehua Qi
Employing opening shielding gas in metal micro-droplet deposition enables lightweight, real-time, eco-friendly manufacturing. However, aluminum alloys, highly sought-after for manufacturing, face challenges in equipment development and experimental research due to their high oxidation reactivity and thermal sensitivity. This study presents a novel approach that combines piezoelectric actuation with dynamic coaxial gas shielding. The method enables stable aluminum droplet printing with micron-level precision in an open environment. Through combined experiments and theoretical models, the impact of oxidation on droplet deposition dynamics, surface morphology, and formation quality was investigated. Results show that even a slight change in the deposition distance would cause significant variations in deposition and oxidation behavior. Increasing the deposition distance not only exacerbates droplet oxidation and dampens droplet oscillation, but also forms oxidation wrinkles on the droplet surface. A higher substrate feed speed also reduces the shielding gas effectiveness. This effect is particularly significant in multi-layer droplet pileup, where heat accumulation delays solidification and exacerbates oxidation in the upper-layer droplets. To address these challenges, a variable-speed printing strategy based on thermal management was proposed. This method suppresses droplet surface oxidation, enabling metallurgical bonding and stable part formation in open environments. This work provides both practical strategies and theoretical insights for oxidation control in high-temperature metal droplet printing under open-environment conditions.
{"title":"Uniform aluminum droplet deposition manufacturing in an open environment: Oxidation suppression and stable printing under coaxial shielding gas","authors":"Yi Zhou , Jun Luo , Lin Su , Lehua Qi","doi":"10.1016/j.jmatprotec.2025.119183","DOIUrl":"10.1016/j.jmatprotec.2025.119183","url":null,"abstract":"<div><div>Employing opening shielding gas in metal micro-droplet deposition enables lightweight, real-time, eco-friendly manufacturing. However, aluminum alloys, highly sought-after for manufacturing, face challenges in equipment development and experimental research due to their high oxidation reactivity and thermal sensitivity. This study presents a novel approach that combines piezoelectric actuation with dynamic coaxial gas shielding. The method enables stable aluminum droplet printing with micron-level precision in an open environment. Through combined experiments and theoretical models, the impact of oxidation on droplet deposition dynamics, surface morphology, and formation quality was investigated. Results show that even a slight change in the deposition distance would cause significant variations in deposition and oxidation behavior. Increasing the deposition distance not only exacerbates droplet oxidation and dampens droplet oscillation, but also forms oxidation wrinkles on the droplet surface. A higher substrate feed speed also reduces the shielding gas effectiveness. This effect is particularly significant in multi-layer droplet pileup, where heat accumulation delays solidification and exacerbates oxidation in the upper-layer droplets. To address these challenges, a variable-speed printing strategy based on thermal management was proposed. This method suppresses droplet surface oxidation, enabling metallurgical bonding and stable part formation in open environments. This work provides both practical strategies and theoretical insights for oxidation control in high-temperature metal droplet printing under open-environment conditions.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119183"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2026-01-02DOI: 10.1016/j.jmatprotec.2025.119195
Zili Zhang , Song Yuan , Chi Fai Cheung , Wei Wu , Ze Li , Kangsen Li , Chunjin Wang
Fluid jet polishing (FJP) has demonstrated significant potential for polishing and figuring of surfaces with complex geometries owing to its flexibility and shape-adaptive capacity, particularly in high-precision optical applications such as X-ray reflectors, extreme ultraviolet lithography, and super-resolution imaging. Despite its advantages, FJP faces two major challenges that hinder its large-scale industrial adoption. The first challenge is the trade-off between surface quality and material removal efficiency. FJP relies solely on the mechanical impacts of abrasives for material removal, leaving erosion pits on the polished surface. Consequently, existing techniques struggle to achieve sub-nanometer precision while maintaining efficient material removal rates. The second challenge arises from the brittle fracture of materials during the FJP process, complicating the achievement of ultra-smooth surfaces with minimal subsurface damage. To address these limitations, this study introduces Submerged Air Jet Chemical Mechanical Polishing (SAJCMP). This method incorporates a novel material removal mechanism, referred to as “nano-reactive-abrasive-laden droplet-induced chemical mechanical removal,” which enables atomic and close-to-atomic precision while significantly improving polishing efficiency. The multi-scale material removal mechanism is elucidated through both experimental investigations and molecular dynamics (MD) simulations. Furthermore, the influence of various polishing parameters on the synergistic effects of chemical and mechanical actions is analyzed using computational fluid dynamics (CFD) simulations, complemented by experimental validation. Polishing experiments conducted on structured arrays and curved surfaces demonstrated that SAJCMP significantly enhances surface quality, preserves form accuracy, and minimizes subsurface damage.
{"title":"High-efficiency submerged air jet chemical mechanical polishing at the atomic and close-to-atomic scale","authors":"Zili Zhang , Song Yuan , Chi Fai Cheung , Wei Wu , Ze Li , Kangsen Li , Chunjin Wang","doi":"10.1016/j.jmatprotec.2025.119195","DOIUrl":"10.1016/j.jmatprotec.2025.119195","url":null,"abstract":"<div><div>Fluid jet polishing (FJP) has demonstrated significant potential for polishing and figuring of surfaces with complex geometries owing to its flexibility and shape-adaptive capacity, particularly in high-precision optical applications such as X-ray reflectors, extreme ultraviolet lithography, and super-resolution imaging. Despite its advantages, FJP faces two major challenges that hinder its large-scale industrial adoption. The first challenge is the trade-off between surface quality and material removal efficiency. FJP relies solely on the mechanical impacts of abrasives for material removal, leaving erosion pits on the polished surface. Consequently, existing techniques struggle to achieve sub-nanometer precision while maintaining efficient material removal rates. The second challenge arises from the brittle fracture of materials during the FJP process, complicating the achievement of ultra-smooth surfaces with minimal subsurface damage. To address these limitations, this study introduces Submerged Air Jet Chemical Mechanical Polishing (SAJCMP). This method incorporates a novel material removal mechanism, referred to as “nano-reactive-abrasive-laden droplet-induced chemical mechanical removal,” which enables atomic and close-to-atomic precision while significantly improving polishing efficiency. The multi-scale material removal mechanism is elucidated through both experimental investigations and molecular dynamics (MD) simulations. Furthermore, the influence of various polishing parameters on the synergistic effects of chemical and mechanical actions is analyzed using computational fluid dynamics (CFD) simulations, complemented by experimental validation. Polishing experiments conducted on structured arrays and curved surfaces demonstrated that SAJCMP significantly enhances surface quality, preserves form accuracy, and minimizes subsurface damage.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119195"},"PeriodicalIF":7.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145939264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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