Journal of Materials Processing Technology最新文献

{"title":"Machine learning aided in situ monitoring of compositional variation during laser additive manufacturing of refractory alloy","authors":"Teng Yang , Jitesh Kumar , Yuqi Jin , Brian Squires , Selvamurugan Palaniappan , Jacob Spencer , Sai Kumar Dussa , Zhaochen Gu , Andrey A. Voevodin , Narendra B. Dahotre","doi":"10.1016/j.jmatprotec.2026.119216","DOIUrl":"10.1016/j.jmatprotec.2026.119216","url":null,"abstract":"<div><div>The present study aimed to conduct <em>in situ</em> composition monitoring during laser-based additive manufacturing of TiZrMoAl<sub>x</sub> refractory complex concentrated alloy (RCCA) using Laser Energy-Assisted Breakdown Spectroscopy (LEABS) system integrated with machine learning (ML). The fs-LEABS system employs an ultra-fast femtosecond pulsed laser (250 fs pulse width, 1 kHz repetition rate) that achieves superior signal-to-noise ratios through athermal ablation mechanisms. This approach yields SNR values of approximately 9 for <em>in situ</em> measurements compared to approximately 5 for conventional <em>ex situ</em> measurements, while minimizing thermal background interference inherent to high-temperature additive manufacturing environments. This in turn assisted in revealing the well-defined characteristic atomic spectral emission lines, which were used for reliable, accurate, real-time quantitative elemental composition analysis. A physics-informed approach based on the ratio of integrated peak areas was combined with ML models to effectively track and interpret composition changes in near real-time. Additionally, a high-speed translation system with high spatial resolution integrated with femtosecond laser energy-assisted breakdown spectroscopy (fs-LEABS) facilitated rapid spatial analysis during AM fabrication involving blended elemental powders with significantly different melting temperatures. During Ti/Zr/Mo/Al RCCA fabrication, Al loss due to vaporization was semi-quantitatively estimated using <em>in situ</em> ML assisted laser energy assisted breakdown spectroscopy analysis. Given that Al has a lower vaporization temperature than Mo, its loss by evaporation was monitored to adjust the Ti/Zr/Mo/Al blend composition accordingly. The proposed system not only provides averaged experimental composition values but also delivers track-by-track, layer-by-layer analysis. This detailed mapping reveals clear vaporization transition behaviors affected by <em>in situ</em> heat accumulation, which align with the behavior predicted by numerical simulations. The Random Forest Regression model achieved R² = 0.95 with mean absolute error of 0.37 at.% and mean absolute percentage error of 5.32 %, successfully predicting aluminum content variations from 4 to 14 at.% in real-time during multi-track, multi-layer fabrication. Validation against Energy Dispersive X-ray Spectroscopy measurements confirmed the system's capability to detect aluminum losses of 3–5 at.% under processing conditions with laser fluence inputs ranging from 120 to 160 J/mm³ . This approach provides a means to monitor and compensate for Al elemental loss, enabling process optimization by tuning the powder composition or adjusting processing parameters to minimize elemental depletion. Although the present work focuses on aluminum vaporization monitoring in TiZrMoAl<sub>x</sub> refractory alloys where elements exhibit significantly different melting and evaporation temp","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119216"},"PeriodicalIF":7.5,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974771","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}

{"title":"Cathode jet and columnar grain suppression in oscillating arc-wire directed energy deposition of titanium alloy","authors":"Kang Sun ,&nbsp;Xiao Xiao ,&nbsp;Shigeaki Uchida ,&nbsp;Pengkang Zhao ,&nbsp;Dongsheng Wu ,&nbsp;Hisaya Komen ,&nbsp;Ning Ma ,&nbsp;Keke Zhang ,&nbsp;Manabu Tanaka ,&nbsp;Huijun Li","doi":"10.1016/j.jmatprotec.2026.119215","DOIUrl":"10.1016/j.jmatprotec.2026.119215","url":null,"abstract":"<div><div>As titanium is a thermionic cathode material, strong cathode jet can easily be caused by gas metal arc welding (GMAW)-based directed energy deposition (DED) of titanium alloys. Additionally, during the DED process, coarse columnar grains are prone to form, which severely affects the performance of the deposited titanium components. Therefore, it remains a challenge to fabricate high-performance titanium alloy components using GMAW-based DED. In this work, these obstacles can be overcome using an oscillating arc. Additionally, the influencing mechanisms of the oscillating arc on the cathode jet, droplet transfer, molten pool flow, microstructure, and mechanical properties were investigated. Experimental and simulation results indicated that the metal vapor near the welding wire in conventional GMAW-based DED was primarily composed of Ti ion (Ti Ⅱ) particles, while the cathode jet was mainly composed of Ti atom (Ti Ⅰ) particles. The oscillating arc reduced the molten pool temperature and caused the cathode jet to move away from the droplet. It also shifted the peak intensity of Ti atom particles from the molten pool to the welding wire, while promoting the ionization of a large number of Ti atom particles into Ti ion particles in the cathode jet region. The oscillating arc also promoted convection in the molten pool and altered the flow patterns, which increased the cooling rate and thereby refining the β and α grains. Oscillating cold metal transfer (CMT)-based DED significantly improved the mechanical properties of Ti6Al4V alloy. This work provides new perspectives and guidance for the engineering applications of GMAW-based DED of titanium alloys.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119215"},"PeriodicalIF":7.5,"publicationDate":"2026-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035332","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}

{"title":"Model-driven multi-step hot metal gas forming of irregular tubular aluminum components: Physically based simulation and experimental validation","authors":"Zhihan Wang ,&nbsp;Pengxiao Yang ,&nbsp;Xinyuan Gao ,&nbsp;Zhennan Bao ,&nbsp;Zhubin He ,&nbsp;Kailun Zheng ,&nbsp;Jiaxin Lv","doi":"10.1016/j.jmatprotec.2026.119213","DOIUrl":"10.1016/j.jmatprotec.2026.119213","url":null,"abstract":"<div><div>Hot metal gas forming (HMGF) is a cutting-edge technology to integrally form hollow complex tubular parts. However, components with spatially curved centerlines and variable cross-sections are difficult to form directly from straight tubular work pieces without fracture. Therefore, a multi-step hot metal gas forming (HMGF) method, which includes CNC bending, pre-forming and hot metal gas forming is proposed and validated in this study, together with a newly developed physically based constitutive model implemented within a finite element framework to capture microstructural and mechanical inheritance across steps. First, representative segments were formed and simulated using a four-step hot metal gas forming (HMGF) route across forming temperatures, internal pressures and pressurization rates. The results indicate that the forming parameters have coupled effects on corner filling and thickness uniformity, revealing inherent trade-offs among temperature, pressure, and pressurization rate. An optimal combination of process parameters was identified, enabling accurate forming of the full-scale component without macroscopic defects at initial diameter of 142 mm. Full-scale trials at initial diameters of 140 mm and 145 mm likewise confirmed accurate prediction of defects and grain-size evolution, demonstrating robust and geometry-independent predictability of both forming defects and microstructural evolution. This study advances a general methodology for parameter optimization and defect suppression in industrial production of complex tubular components.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119213"},"PeriodicalIF":7.5,"publicationDate":"2026-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974711","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}

{"title":"Optimizing strength-ductility synergy in dissimilar superalloy joint via low-temperature spark plasma diffusion bonding and post-bonding heat treatment","authors":"Weiqi Yang ,&nbsp;Yekun Feng ,&nbsp;Sujun Liu ,&nbsp;Lili Xing ,&nbsp;Dongbai Sun ,&nbsp;Di Yu ,&nbsp;Peng He ,&nbsp;Tiesong Lin ,&nbsp;Jincheng Lin","doi":"10.1016/j.jmatprotec.2026.119210","DOIUrl":"10.1016/j.jmatprotec.2026.119210","url":null,"abstract":"<div><div>Dissimilar joining of GH5188 and GH3536 superalloys faces the long-standing problem of interfacial brittleness and limited ductility. This challenge mainly originates from oxide-film retention, insufficient diffusion, and carbide accumulation at the bonding interface. To resolve these issues, we developed a low-temperature spark plasma diffusion bonding (SPDB) route combined with a post-bond heat treatment, where pulsed-current-induced local heating, oxide-film disruption and short-range mass transport provide clear processing advantages over conventional diffusion bonding. Key experiments demonstrate that a defect-free joint can be produced at 850 °C within only 10 min, forming a straight bonded line containing MnCr₂O₄ spinel, M₂₃C₆ carbides and deformed solid solutions, with a tensile strength of 524 MPa but limited elongation (15.2 %). Subsequent heat treatment at 1100 °C for 1 h triggers interfacial recrystallisation, cross-interface grain growth, and partial dissolution/redistribution of interfacial M₂₃C₆ carbides, transforming the sharp bond line into a recrystallized and compositionally graded diffusion zone. As a result, the joint achieves a strength of 721 MPa and an elongation of 33.8 % at room temperature. At 700 °C, the post-treated joint maintains a strength of 428 MPa and an elongation of 18.2 %, which are 1.75 and 3.37 times higher than those of the as-bonded joint, accompanied by a fracture-mode transition from interfacial cleavage to ductile failure. Overall, this study demonstrates a SPDB + heat treatment strategy capable of overcoming the metallurgical incompatibility of Co-/Ni-based superalloys and achieving a stable strength-ductility synergy at both ambient and elevated temperatures.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119210"},"PeriodicalIF":7.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923569","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}

{"title":"Defect formation mechanisms and control strategies for high-performance welding of medium-thick components","authors":"Yue Qiu ,&nbsp;Minjie Song ,&nbsp;Yilin Wang ,&nbsp;Shaoning Geng ,&nbsp;Leshi Shu ,&nbsp;Wei Wang","doi":"10.1016/j.jmatprotec.2025.119193","DOIUrl":"10.1016/j.jmatprotec.2025.119193","url":null,"abstract":"<div><div>High-power laser-arc hybrid welding is a critical technology for achieving single-pass double-sided welding of medium-thick components, while the mechanisms of defect formation and suppression, as well as the microstructural effects on mechanical performance under full penetration, remain unclear. This study integrates extensive welding experiments with an advanced ray-tracing based computational fluid dynamics model to systematically reveal the formation mechanisms and suppression strategies of incomplete penetration, root humping, and upper surface collapse. In addition, electron backscatter diffraction analysis clarifies the microstructural strengthening mechanisms governing weld performance. On this basis, both a wide process window for stable weld formation and a refined window for high-performance welding are established. Experimental results show that laser power and welding velocity mainly affect the morphology of the lower weld surface, whereas wire feeding rate predominantly controls the upper surface. Simulations demonstrate that in the incomplete penetration state, the keyhole–molten pool system exhibits quasi-periodic oscillations, driven by the cyclic expansion and contraction of the keyhole bottom opening, resulting in periodic fluctuations of penetration depth. Root humping and upper surface collapse are primarily caused by the violent keyhole fluctuations at the keyhole bottom. Both experiments and simulations confirm that matching high laser power with high welding velocity and wire feeding rate effectively suppresses these fluctuations, reducing the standard deviation of keyhole area variation from 0.094 mm² to 0.065 mm². Under fully penetrated conditions, a moderate heat input intensifies molten pool convection, which leads to dendrite fragmentation and the formation of new intragranular nucleation sites. This process intensifies the lateral competition growth between grains, promotes grain refinement, increases dislocation density, and elevates the fraction of high-angle grain boundaries. Meanwhile, the enlarged mushy zone and extended solidification time facilitate the δ to γ transformation, collectively improving tensile strength. Accordingly, an optimized and wide process window for well-formed welds is defined by laser power of 10–18 kW, welding velocity of 20–36 mm/s, and wire feeding rate of 233–333 mm/s. Within this window, the high-quality and high-strength process window, defined by a laser power of 15–18 kW, welding velocity of 24–36 mm/s, and wire feeding rate of 233–290 mm/s, enables stable full penetration and defect-free morphology on both sides, achieving single-pass welding of 10 mm-scale medium-thick components.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119193"},"PeriodicalIF":7.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146035331","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}

{"title":"Active gas-film insulation method for controllable electrochemical machining deep-narrow grooves","authors":"Jinpeng Zhao ,&nbsp;Wanfei Ren ,&nbsp;Jinkai Xu ,&nbsp;Huihui Sun ,&nbsp;Haoran Deng ,&nbsp;Qingwei Wang","doi":"10.1016/j.jmatprotec.2026.119208","DOIUrl":"10.1016/j.jmatprotec.2026.119208","url":null,"abstract":"<div><div>High-precision deep and narrow grooves (DNG) are widely used in the aerospace industry. As one of the effective methods for machining deep and narrow grooves, electrochemical machining (ECM) produces uncontrollable stray corrosion during the machining process, which induces the formation of progressive taper on the sidewalls. This study innovatively proposes an innovative electrochemical machining technology named “Active gas-film insulation method for controllable electrochemical machining”. The movement paths and variation mechanisms of the gas film in the electrolyte environment are analyzed through theoretical analysis and gas-liquid two-phase flow simulation. A gas film electrical signal inversion localization method was designed to assist the experiments, realizing the conversion of the dynamic gas film position into electrical signals and thereby enabling real-time observation of the experimental process. Based on the characterization of the surface quality, contour morphology, and taper measurement of the machined deep and narrow grooves, an in-depth analysis of the formation law of gas film insulation is conducted. It is found that the insulation effect of the gas film exhibits consistent regularity under the optimization of the combined parameters of electrolyte pressure and submerged gas film pressure. Finally, the sidewall taper of the deep and narrow grooves machined by gas film insulation-based electrochemical machining is reduced by approximately 98 % compared with traditional electrochemical machining. To reveal the flexible applicability of gas film insulation, special-shaped deep and narrow groove structures are machined through the dynamic regulation of the insulation area. This study provides a new approach for achieving electrochemical machining of high-precision, controllable complex structures.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119208"},"PeriodicalIF":7.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974770","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}

{"title":"Revealing the three-dimensional morphology and evolution mechanism of porosity at the flow end in non-heat-treated high-pressure die-cast AlSi9MnVZr alloy","authors":"Zunian He ,&nbsp;Yixian Liu ,&nbsp;Aoxiang Wan ,&nbsp;Pengzhan Wang ,&nbsp;Zhengda Lu ,&nbsp;Zhihong Jia ,&nbsp;Shoumei Xiong","doi":"10.1016/j.jmatprotec.2026.119209","DOIUrl":"10.1016/j.jmatprotec.2026.119209","url":null,"abstract":"<div><div>Under high-pressure die casting (HPDC) conditions, extensive porosity forms at the late stage of flow, which significantly deteriorates the mechanical properties of the casting. Due to experimental precision and complexity, observing the evolution of these pores through 3D reconstruction is challenging. In this work, a lamellar hole formation phenomenon at the end of the flow samples was found, accompanied by substantial microstructure changes of the AlSi9MnVZr alloy. Based on this, the length of the flow end is defined. The subsequent evolution of pores after lamellar hole formation was studied under different gate speeds. A Lattice Boltzmann Method (LBM) based simulation framework was employed to model the flow behavior in the flow end region of casting samples under different Reynolds numbers (Re) and effective flow cross sections, showing agreement with experimental observations. By introducing the concepts of critical gate speed and stoppage point, the changes in fluidity and mechanical properties at different gate speeds were discussed. The findings establish a mechanism for porosity evolution at the flow end and highlight the limited benefits of increasing gate speed beyond the critical value. The presented results demonstrate that maintaining the gate speed close to the critical gate speed enables both high fluidity and reduced porosity at the flow end.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119209"},"PeriodicalIF":7.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923570","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}

{"title":"An innovative micro-manufacturing technology for the development of aluminium coated magnesium micro components","authors":"R. Srivastava ,&nbsp;B. Venkatesh ,&nbsp;S.K. Panigrahi","doi":"10.1016/j.jmatprotec.2026.119200","DOIUrl":"10.1016/j.jmatprotec.2026.119200","url":null,"abstract":"<div><div>Miniaturised micro components with high aspect ratios have immense applications in aerospace, biomedical, and micro-electromechanical systems (MEMS). Surface wear and corrosion severely affect the performance of miniaturised components, particularly in their long-term use in reactive or aggressive environmental conditions. Therefore, the manufacturing of high aspect ratio miniaturised components with a protective layer of non-reactive materials is challenging yet has immense utility in the biomedical and MEMS sectors. The present approach aims to provide a consistent and durable coating on the inner periphery of axisymmetric micro components with high aspect ratios. As a case study, the difficult-to-deform Mg (AZ31) alloy has been selected as the primary layer material, which exhibits poor corrosion properties. The primary material, Mg (AZ31), is coated with a corrosion-resistant Al (Al1060) alloy as a secondary layer. The objective of developing layered micro billets to facilitate microextrusion was achieved through an optimised strategy consisting of: (i) Chemical and mechanical treatment, (ii) Severe rolling-based deformation induced processing, and (iii) Micro layered billet extraction. These layered micro billets were subjected to micro backward and micro compound extrusion processes to mass fabricate coated micro cups and micro double cups, respectively, in a single step. Through analysis of manufacturability, mechanical properties, and defect propensity, tests were carried out at temperatures ranging from room temperature (RT) to 400 °C. The diffusional interfacial phase evolution and the role of intermetallic compounds, as well as the dynamic recrystallisation mechanism in achieving an optimum coating, were established through detailed interfacial microstructural and mechanical characterisation. A new innovative manufacturing process for developing coated micro cups and micro double cups has been established.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119200"},"PeriodicalIF":7.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974767","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}

{"title":"Beyond imaging: Optical emission spectroscopy for mechanistic diagnosis of plasma plume and spatter dynamics in laser DED","authors":"Mohit Singh ,&nbsp;Misba Amin ,&nbsp;Arun Kumar R ,&nbsp;S.L. Anoop ,&nbsp;Ravi K R","doi":"10.1016/j.jmatprotec.2026.119199","DOIUrl":"10.1016/j.jmatprotec.2026.119199","url":null,"abstract":"<div><div>Laser-directed energy deposition (DED) is governed by complex interactions between the laser beam, powder stream, and melt pool, where plasma plume fluctuations and spatter ejection dictate process stability. High-speed imaging has provided valuable qualitative insights into these dynamics, but its limited temporal resolution, large data volume, and reliance on thresholding restrict its use for continuous monitoring. This work establishes optical emission spectroscopy (OES) as a quantitative, imaging-independent diagnostic by identifying the Fe I 520.79 nm line as a high-fidelity spectral proxy for plasma plume activity in SS316L DED. Single-layer clads were deposited across a broad range of volumetric energy densities, during which time-resolved OES (∼1 ms sampling) captured plume oscillations and their direct correlation with clad morphology and regime transitions. These transitions spanned from lack of fusion through conduction and transition to keyhole mode, as identified through depth-aspect-ratio analysis. High-speed imaging was used only for qualitative cross-validation of spatter birth and trajectory. A threshold-dependent shift in spatter formation was identified, where lower plasma-plume intensities corresponded to Kelvin–Helmholtz-driven droplet ejection, while higher intensities triggered Plateau–Rayleigh instability and high-velocity jet spatters. An exponential correlation (R² ≈ 0.98) between Fe I 520.79 nm intensity and spatter number enables compact, imaging-free quantification of instability events with millisecond precision. These results establish OES as a generalizable, physics-driven “smart-sensor” capable of resolving melt-pool instability regimes and spatter mechanisms in real time, providing a scalable foundation for closed-loop process control in industrial DED.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119199"},"PeriodicalIF":7.5,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145923634","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}

{"title":"Correlation between microstructure and residual stress formation in friction stir welded armor steels characterized by neutron diffraction","authors":"Jhoan Guzman ,&nbsp;Kaue C. Riffel ,&nbsp;Martin McDonnell ,&nbsp;Jeffrey Bunn ,&nbsp;Andrew Payzant ,&nbsp;Doug Kyle ,&nbsp;Antonio J. Ramirez","doi":"10.1016/j.jmatprotec.2026.119198","DOIUrl":"10.1016/j.jmatprotec.2026.119198","url":null,"abstract":"<div><div>Friction stir welding (FSW) is a solid-state joining process that minimizes the heat-affected zone (HAZ) compared with fusion-based arc welding, making it well suited for joining martensitic armor steels where hardness and ballistic resistance are critical. This study investigates residual stress formation in three defect-free FSW butt-joint configurations relevant to armored-vehicle fabrication: similar rolled homogeneous armor (RHA–RHA, Case 1), similar high-hardness armor (HHA–HHA, Case 2), and dissimilar HHA–RHA (Case 3) joints produced under temperature-controlled conditions (770 °C). Neutron diffraction was employed to quantify the magnitude and spatial distribution of residual stresses in the longitudinal, transverse, and normal directions and to correlate them with weld microstructure and hardness. Tensile residual stresses were concentrated in the softened HAZ, reaching approximately 300 MPa for Case 2 and 400 MPa for Case 1 (≈50–70 % of the base-metal yield strength; ∼581 MPa for RHA and ∼566 MPa for HHA), while compressive residual stresses dominated the stir zone. The spatial extent of tensile stresses scaled with the width of the softened HAZ, which was largest in the dissimilar HHA–RHA joint and smallest in the HHA–HHA joint. Full-width-at-half-maximum (FWHM) analysis revealed low microstrain in overtempered HAZ regions and high microstrain in the stir zone associated with severe plastic deformation and fresh martensite formation. This work demonstrates that residual stress evolution in FSW of martensitic armor steels is governed not primarily by peak temperature or thermal contraction, as inferred from fusion-welding analogies, but by the competition between transformation-induced volumetric expansion and tempering-induced stress relaxation. The relative dominance of these mechanisms is shown to depend on alloy hardenability and local thermal history, leading to more extensive HAZ softening and broader tensile stress regions in the lower-hardenability RHA steel. These findings establish a transferable mechanistic framework for optimizing solid-state joining strategies in high-strength steels and other transformation-hardening alloys beyond armor applications.</div></div>","PeriodicalId":367,"journal":{"name":"Journal of Materials Processing Technology","volume":"349 ","pages":"Article 119198"},"PeriodicalIF":7.5,"publicationDate":"2026-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145903991","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}