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":"2025-12-21","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 : 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":"2025-12-16","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 : 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":"2025-12-15","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 : 2025-12-13DOI: 10.1016/j.jmatprotec.2025.119184
Yuji Li , Jin Huang , Zhenghua Liu , Delong Shi , Beining Li , Weiwei He , Fanbo Meng
In the Laser Powder Bed Fusion (LPBF) forming process of oxide ceramics, Due to the inherently loose structure of the powder bed and the poor thermal conductivity of oxide ceramics, issues such as intense melt pool spattering and uneven melting/solidification frequently arise. To address this challenge, this study proposes an in-situ modulation and modification strategy for the powder bed. Thermal and kinetic models were established to analyze the melting process of the modified powder bed, and multi-scale validation was conducted in conjunction with experimental work.The modified powder bed demonstrates significant suppression of melt pool spattering behavior.Compared with the unmodified control samples, the modified components exhibited reductions in surface roughness values Ra and Rz by 88.6 % and 28.6 %, respectively. In-depth mechanistic analysis revealed that the auxiliary materials infiltrated the interparticle gaps by capillary forces, and sol gelation substantially enhanced the interparticle bonding strength. This phenomenon effectively restrained the particle spattering dynamics under recoil pressure. Concurrently, the incomplete combustion of benzyl alcohol generated an in situ nanoscale carbon layer on the powder bed surface, reducing the melt-pool temperature gradients. This phenomenon weakens the Marangoni convection intensity driven by the surface tension gradients, thereby extending the time window for melt spreading and leveling. The in-situ powder bed modulation and modification strategy provides a new theoretical basis for improving the forming quality and microstructural optimization of oxide ceramic components fabricated by LPBF. Importantly, this strategy offers a novel process pathway for addressing melt pool instability and defect control in LPBF of various material systems.
{"title":"A powder-bed in-situ modification strategy for surface quality enhancement in laser powder bed fusion: A case study on oxide ceramics","authors":"Yuji Li , Jin Huang , Zhenghua Liu , Delong Shi , Beining Li , Weiwei He , Fanbo Meng","doi":"10.1016/j.jmatprotec.2025.119184","DOIUrl":"10.1016/j.jmatprotec.2025.119184","url":null,"abstract":"<div><div>In the Laser Powder Bed Fusion (LPBF) forming process of oxide ceramics, Due to the inherently loose structure of the powder bed and the poor thermal conductivity of oxide ceramics, issues such as intense melt pool spattering and uneven melting/solidification frequently arise. To address this challenge, this study proposes an in-situ modulation and modification strategy for the powder bed. Thermal and kinetic models were established to analyze the melting process of the modified powder bed, and multi-scale validation was conducted in conjunction with experimental work.The modified powder bed demonstrates significant suppression of melt pool spattering behavior.Compared with the unmodified control samples, the modified components exhibited reductions in surface roughness values Ra and Rz by 88.6 % and 28.6 %, respectively. In-depth mechanistic analysis revealed that the auxiliary materials infiltrated the interparticle gaps by capillary forces, and sol gelation substantially enhanced the interparticle bonding strength. This phenomenon effectively restrained the particle spattering dynamics under recoil pressure. Concurrently, the incomplete combustion of benzyl alcohol generated an in situ nanoscale carbon layer on the powder bed surface, reducing the melt-pool temperature gradients. This phenomenon weakens the Marangoni convection intensity driven by the surface tension gradients, thereby extending the time window for melt spreading and leveling. The in-situ powder bed modulation and modification strategy provides a new theoretical basis for improving the forming quality and microstructural optimization of oxide ceramic components fabricated by LPBF. Importantly, this strategy offers a novel process pathway for addressing melt pool instability and defect control in LPBF of various material systems.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119184"},"PeriodicalIF":7.5,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145798129","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 : 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":"2025-12-11","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 : 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":"2025-12-10","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 : 2025-12-10DOI: 10.1016/j.jmatprotec.2025.119179
Zekun Yang , Zhanli Yang , Dakui Fei , Yanxu Wang , Guofu Wang , Guangnan Zhao , Xin Yuan , Bing Lu , Ziran Wang , Kai Xu
Achieving flexible and cost-effective in-situ alloying within multi-wire submerged arc welding (multi-wire SAW) represents a core challenge for manufacturing high-performance pipeline steels. This study systematically investigates how the spatial position of the alloying source (a bypass cold wire) relative to the energy source (the multi-arc system) governs the physical metallurgy during the welding process. The results reveal that the cold wire feeding position has a decisive influence on both process stability and metallurgical behavior. In this confined-arc process, the highest elemental recovery was counter-intuitively obtained in the most energy-intensive region—the coupled arc zone. However, this high-recovery process window was accompanied by severe arc instability (the average coefficient of variation for the main wire current increased from 4.20 % to 7.08 %, increasing by nearly 70 %), leading to significant chemical segregation and microstructural degradation. To explain this anomalous phenomenon and resolve the aforementioned conflict, this work proposes the "Arc Cavity Confined Reaction" model. This model, for the first time, scientifically demonstrates from the dual mechanisms of physical confinement and chemical protection how the flux-formed cavity transforms conventional arc burn-off" into a controlled "evaporation-confinement- recondensation" cycle, thereby amending the applicability of classical loss theories in confined-arc processes. Based on this theoretical framework, the "molten pool stabilization zone" behind the arcs was ultimately identified as the optimal process window to decouple elemental recovery from process stability, under which condition the weld metal's low-temperature impact toughness (-10°C) reached 165.7 J. This work fundamentally advances the understanding of elemental mass transfer in confined-arc environments, providing a new theoretical framework and critical process guidelines for all advanced materials processing technologies that rely on slag protection.
{"title":"Effect of bypass cold wire spatial position on process stability and elemental transfer in submerged arc welding for in situ alloying","authors":"Zekun Yang , Zhanli Yang , Dakui Fei , Yanxu Wang , Guofu Wang , Guangnan Zhao , Xin Yuan , Bing Lu , Ziran Wang , Kai Xu","doi":"10.1016/j.jmatprotec.2025.119179","DOIUrl":"10.1016/j.jmatprotec.2025.119179","url":null,"abstract":"<div><div>Achieving flexible and cost-effective in-situ alloying within multi-wire submerged arc welding (multi-wire SAW) represents a core challenge for manufacturing high-performance pipeline steels. This study systematically investigates how the spatial position of the alloying source (a bypass cold wire) relative to the energy source (the multi-arc system) governs the physical metallurgy during the welding process. The results reveal that the cold wire feeding position has a decisive influence on both process stability and metallurgical behavior. In this confined-arc process, the highest elemental recovery was counter-intuitively obtained in the most energy-intensive region—the coupled arc zone. However, this high-recovery process window was accompanied by severe arc instability (the average coefficient of variation for the main wire current increased from 4.20 % to 7.08 %, increasing by nearly 70 %), leading to significant chemical segregation and microstructural degradation. To explain this anomalous phenomenon and resolve the aforementioned conflict, this work proposes the \"Arc Cavity Confined Reaction\" model. This model, for the first time, scientifically demonstrates from the dual mechanisms of physical confinement and chemical protection how the flux-formed cavity transforms conventional arc burn-off\" into a controlled \"evaporation-confinement- recondensation\" cycle, thereby amending the applicability of classical loss theories in confined-arc processes. Based on this theoretical framework, the \"molten pool stabilization zone\" behind the arcs was ultimately identified as the optimal process window to decouple elemental recovery from process stability, under which condition the weld metal's low-temperature impact toughness (-10°C) reached 165.7 J. This work fundamentally advances the understanding of elemental mass transfer in confined-arc environments, providing a new theoretical framework and critical process guidelines for all advanced materials processing technologies that rely on slag protection.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119179"},"PeriodicalIF":7.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749007","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 : 2025-12-09DOI: 10.1016/j.jmatprotec.2025.119180
Sebastian Fritsche , Jonathan Draper , Ricardo Henrique Buzolin , Ryan Maxwell , Athanasios Toumpis , Alexander Galloway , Sergio T. Amancio-Filho
Refill Friction Stir Spot Welding is a promising technique for joining lightweight aluminium alloys such as AA7075-T6. However, hook defects—microstructural discontinuities at the weld interface—can significantly compromise joint integrity. Additionally, variations in heat input during welding influence microstructure evolution and mechanical properties. This study investigates the influence of process parameters and the hook defect on the quasi-static performance of AA7075-T6 RFSSW joints. Joints with various parameter combinations were analysed using optical microscopy, electron backscatter diffraction, tensile lap shear testing, and microhardness mapping, alongside thermocouple measurements of process temperatures. A semi-quantitative heat input model was developed to provide new insights into thermal characteristics and their effects on microstructural evolution. The obtained results show a decrease in ultimate lap shear force for high upward or downward-directed hooks. A welding time of 4 s and rotational speed of 2200 rpm resulted in optimal joint performance, achieving an ultimate lap shear force of 12.2 kN and sufficient heat input to prevent refill defects. Extended welding durations led to overheating and additional defects in the stir zone, while low welding time or rotational speed significantly influenced welding temperatures, heat input, and microstructural characteristics at the shoulder plunge path periphery. The findings emphasise the critical role of dynamic recrystallisation in the resulting microstructures and their impact on mechanical performance. Fatigue strength of the optimised joints exceeds RFSSW joints reported in the literature, underscoring the effectiveness of the selected process parameters in enhancing joint durability. Furthermore, the established semi-quantitative heat input model links energy partitioning to defect formation and microhardness of the joints. This provides new insights into the RFSSW process and enables knowledge transfer to other RFSSW applications.
{"title":"Refill friction stir spot welding of high-strength aluminium alloys: Linking hook formation and calculated heat input to microstructure and mechanical properties","authors":"Sebastian Fritsche , Jonathan Draper , Ricardo Henrique Buzolin , Ryan Maxwell , Athanasios Toumpis , Alexander Galloway , Sergio T. Amancio-Filho","doi":"10.1016/j.jmatprotec.2025.119180","DOIUrl":"10.1016/j.jmatprotec.2025.119180","url":null,"abstract":"<div><div>Refill Friction Stir Spot Welding is a promising technique for joining lightweight aluminium alloys such as AA7075-T6. However, hook defects—microstructural discontinuities at the weld interface—can significantly compromise joint integrity. Additionally, variations in heat input during welding influence microstructure evolution and mechanical properties. This study investigates the influence of process parameters and the hook defect on the quasi-static performance of AA7075-T6 RFSSW joints. Joints with various parameter combinations were analysed using optical microscopy, electron backscatter diffraction, tensile lap shear testing, and microhardness mapping, alongside thermocouple measurements of process temperatures. A semi-quantitative heat input model was developed to provide new insights into thermal characteristics and their effects on microstructural evolution. The obtained results show a decrease in ultimate lap shear force for high upward or downward-directed hooks. A welding time of 4 s and rotational speed of 2200 rpm resulted in optimal joint performance, achieving an ultimate lap shear force of 12.2 kN and sufficient heat input to prevent refill defects. Extended welding durations led to overheating and additional defects in the stir zone, while low welding time or rotational speed significantly influenced welding temperatures, heat input, and microstructural characteristics at the shoulder plunge path periphery. The findings emphasise the critical role of dynamic recrystallisation in the resulting microstructures and their impact on mechanical performance. Fatigue strength of the optimised joints exceeds RFSSW joints reported in the literature, underscoring the effectiveness of the selected process parameters in enhancing joint durability. Furthermore, the established semi-quantitative heat input model links energy partitioning to defect formation and microhardness of the joints. This provides new insights into the RFSSW process and enables knowledge transfer to other RFSSW applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119180"},"PeriodicalIF":7.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748956","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 : 2025-12-09DOI: 10.1016/j.jmatprotec.2025.119181
Tao Zhu , Xiangjun Xiang , Qiang Gong , Jiaxing Wen , Lai Wei , Tian Huang , Hongkai Jin , Changqiu Chen , Huabin He , Kaihua Sun , Xianfeng Shen , Shuke Huang
Melt pool instability remains a critical barrier to the reliability of Powder Bed Fusion by Laser Beam Melting (PBF-LB/M). While beam shaping is a promising regulatory strategy, the underlying dynamic mechanisms governing its stabilizing effect are not yet fully resolved. By integrating in-situ radiation monitoring with multiphysics simulations on HR-2 austenitic stainless steel, this work systematically elucidates the intrinsic mechanism through which a flat-top beam mitigate melt pool oscillation. The research reveals that the uniform energy distribution of the flat-top beam fundamentally suppresses the steep temperature gradients within the melt pool and the consequent Marangoni convection, thereby significantly enhancing hydrodynamic stability. This stability was validated across multiple dimensions. Within a wide processing window (power 170–450 W, speed 500–1200 mm/s), the use of a flat-top beam, compared to a Gaussian beam, reduced the peak melt pool temperature by an average of 500°C and decreased the maximum fluid velocity by approximately 50 %. Crucially, this profound stabilization of the internal thermo-fluid dynamics is directly reflected in the time-frequency analysis of the real-time photodiode signal, which captures the thermal radiation emitted from the melt pool. The flat-top beam effectively filters out high-frequency (>1 kHz) spectral energy by over 80 %, transforming the melt pool dynamics from a stochastic, high-frequency oscillatory state driven by intense convection to a predictable, low-frequency dominant regime. Ultimately, this study establishes and verifies a cascading physical mechanism: energy homogenization leads to the mitigation of temperature gradients and peak temperatures, which in turn suppresses Marangoni flow velocity and results in a transition of melt pool oscillations from high-frequency, erratic fluctuations to low-frequency, periodic ones. This work provides a critical theoretical basis and a frequency-domain diagnostic tool for leveraging beam shaping to achieve high-stability PBF-LB/M additive manufacturing.
{"title":"Regulation of PBF-LB/M melt pool oscillation behavior via beam shaping: A study based on time-frequency characteristics of coaxial radiation signals","authors":"Tao Zhu , Xiangjun Xiang , Qiang Gong , Jiaxing Wen , Lai Wei , Tian Huang , Hongkai Jin , Changqiu Chen , Huabin He , Kaihua Sun , Xianfeng Shen , Shuke Huang","doi":"10.1016/j.jmatprotec.2025.119181","DOIUrl":"10.1016/j.jmatprotec.2025.119181","url":null,"abstract":"<div><div>Melt pool instability remains a critical barrier to the reliability of Powder Bed Fusion by Laser Beam Melting (PBF-LB/M). While beam shaping is a promising regulatory strategy, the underlying dynamic mechanisms governing its stabilizing effect are not yet fully resolved. By integrating in-situ radiation monitoring with multiphysics simulations on HR-2 austenitic stainless steel, this work systematically elucidates the intrinsic mechanism through which a flat-top beam mitigate melt pool oscillation. The research reveals that the uniform energy distribution of the flat-top beam fundamentally suppresses the steep temperature gradients within the melt pool and the consequent Marangoni convection, thereby significantly enhancing hydrodynamic stability. This stability was validated across multiple dimensions. Within a wide processing window (power 170–450 W, speed 500–1200 mm/s), the use of a flat-top beam, compared to a Gaussian beam, reduced the peak melt pool temperature by an average of 500°C and decreased the maximum fluid velocity by approximately 50 %. Crucially, this profound stabilization of the internal thermo-fluid dynamics is directly reflected in the time-frequency analysis of the real-time photodiode signal, which captures the thermal radiation emitted from the melt pool. The flat-top beam effectively filters out high-frequency (>1 kHz) spectral energy by over 80 %, transforming the melt pool dynamics from a stochastic, high-frequency oscillatory state driven by intense convection to a predictable, low-frequency dominant regime. Ultimately, this study establishes and verifies a cascading physical mechanism: energy homogenization leads to the mitigation of temperature gradients and peak temperatures, which in turn suppresses Marangoni flow velocity and results in a transition of melt pool oscillations from high-frequency, erratic fluctuations to low-frequency, periodic ones. This work provides a critical theoretical basis and a frequency-domain diagnostic tool for leveraging beam shaping to achieve high-stability PBF-LB/M additive manufacturing.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119181"},"PeriodicalIF":7.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748957","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 : 2025-12-08DOI: 10.1016/j.jmatprotec.2025.119178
Luyao Li , Yu Zhang , Jinbiao Huang , Zhe Chen , Xiangyang Yu , Wei Li , Jiasen Sun , Kangyu Lin , Chenchen Yuan , Jiang Ma
The design of materials with desirable and tailorable properties is a long-standing goal within materials science, where composites represent a key strategy. However, a central dilemma in conventional composite manufacturing is that the thermal energy required to form strong interfacial bonds often simultaneously induces detrimental side effects, including interfacial reactions and reinforcement degradation. To resolve this generic conflict, we introduce a versatile "cold manufacturing" strategy utilizing metallic glasses as matrices. By exploiting an athermal ultrasonic vibration mechanism—which induces transient liquid-like behavior in metallic glasses without thermal activation—we achieve seamless interfacial bonding across diverse conductors, insulators, metals, and non-metals via oxide-layer-penetrating diffusion at ambient conditions. Crucially, successful fabrication underwater and in liquid nitrogen definitively demonstrates the technique's purely athermal nature, avoiding any thermal degradation pathways. By tuning metallic glasses binder ratios and additive compositions, we precisely engineer mechanical properties (Vickers hardness: 400–1450 HV) and magnetic response (saturation magnetization: 0–158.6 emu/g), forming robust bonds. This work thus establishes a versatile and fundamentally distinct composite manufacturing platform, opening a generic pathway to multifunctional composites free from the intrinsic limitations of heat.
{"title":"Cold manufacturing of metallic glass-based composites by ultrasonic vibrations","authors":"Luyao Li , Yu Zhang , Jinbiao Huang , Zhe Chen , Xiangyang Yu , Wei Li , Jiasen Sun , Kangyu Lin , Chenchen Yuan , Jiang Ma","doi":"10.1016/j.jmatprotec.2025.119178","DOIUrl":"10.1016/j.jmatprotec.2025.119178","url":null,"abstract":"<div><div>The design of materials with desirable and tailorable properties is a long-standing goal within materials science, where composites represent a key strategy. However, a central dilemma in conventional composite manufacturing is that the thermal energy required to form strong interfacial bonds often simultaneously induces detrimental side effects, including interfacial reactions and reinforcement degradation. To resolve this generic conflict, we introduce a versatile \"cold manufacturing\" strategy utilizing metallic glasses as matrices. By exploiting an athermal ultrasonic vibration mechanism—which induces transient liquid-like behavior in metallic glasses without thermal activation—we achieve seamless interfacial bonding across diverse conductors, insulators, metals, and non-metals via oxide-layer-penetrating diffusion at ambient conditions. Crucially, successful fabrication underwater and in liquid nitrogen definitively demonstrates the technique's purely athermal nature, avoiding any thermal degradation pathways. By tuning metallic glasses binder ratios and additive compositions, we precisely engineer mechanical properties (Vickers hardness: 400–1450 HV) and magnetic response (saturation magnetization: 0–158.6 emu/g), forming robust bonds. This work thus establishes a versatile and fundamentally distinct composite manufacturing platform, opening a generic pathway to multifunctional composites free from the intrinsic limitations of heat.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"348 ","pages":"Article 119178"},"PeriodicalIF":7.5,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145749008","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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