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Effects of heat treatment on microstructures and properties of a heterostructured alloy with dissimilar components fabricated by WAAM

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Rare Metals 2024年第9期43卷 4441-4461页

作者： Ming-Cai Pan Jun-Qiang Xu Yong Peng Ning-Ning Liang Si Lan Qi Zhou Ke-Hong Wang School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Nanjing 210094China

Heat treatment significantly influences homogeneous material microstructures and mechanical properties,which can be improved by an optimal heat treatment ***,heat treatment application to heterogeneous materials presents significant challenges due to compositional and microstructural ***,a laminated heterostructured alloy comprising alternating316L stainless steel(SS)and 18Ni300 maraging steel(MS)layers fabricated using wire and arc additive manufacturing was investigated.A solution treatment was applied at900℃for 0.5 ***,the solution-treated and asfabricated(AF)samples were aged at 500℃for 4 h;these samples were denoted SA and AT,*** AT phase compositions and orientations were similar to those of *** SA 316L SS layer resembled that of AF,but the SA 18Ni300 MS layers exhibited a reduced austenite phase fraction and refined grain size,attributable to solid-state *** the AT sample,aging induced the formation of nanoscale acicularωphase and ellipsoidal Ni_(3)Ti,Fe_(2)Mo,and X precipitates in the 18Ni300 MS ***,the SA precipitates contained acicular Fe Ni_(2)and ellipsoidalω,Ni_(3)Ti,and X precipitates,and their fractions were lower than those in AT ***18Ni300 MS layer microhardness in the heat-treated samples increased due to nanoprecipitation,but the 316L SS layer microhardness resembled that of *** AT and SA ultimate tensile strengths increased to(1360±50)and(1473±41)MPa,respectively,attributable to precipitation *** SA 316L SS layer exhibited a high stress-induced martensite fraction,enhancing the ductility of heated samples.

关键词： Laminated heterostructured alloy Heat treatment Wire and arc additive manufacturing Microstructure Mechanical property

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Processing,microstructure,and mechanical properties of wire arc additively-manufactured AZ91 magnesium alloy using cold arc process

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Transactions of Nonferrous Metals Society of China 2025年第1期35卷 91-104页

作者： Bai-hao CAI Ji-kang FAN Jie LI Dong-qing YANG Yong PENG Ke-hong WANG Key Laboratory of Controlled Arc Intelligent Additive Technology Ministry of Industry and Information TechnologyNanjing University of Science and TechnologyNanjing 210094China School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China

Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties were *** results showed that the cold arc process reduced splashing at the moment of liquid bridge breakage and effectively shortened the droplet transfer *** microstructures of the deposited samples exhibited layered characteristics with alternating distributions of coarse and fine *** layer-by-layer deposition,the β-phase precipitated and grew preferentially along grain boundaries,while the fineη-Al_(8)Mn_(5)phase was dispersed in the α-Mg *** mechanical properties of the CA-WAAM deposited sample showed isotropic *** ultimate tensile strength and elongation in the building direction(BD)were 282.7 MPa and 14.2%,*** microhardness values of the deposited parts were relatively uniform,with an average value of HV 69.6.

关键词： AZ91 magnesium alloy droplet transfer microstructure mechanical properties cold arc process

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Crack healing and strength-ductility enhancement of CM247LC alloy via laser powder bed re-melting followed by hot isostatic pressing and heat treatment

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Materials Characterization 2025年 225卷

作者： Wang, Qiangkun Zhang, Wei Gao, Pengfei Wang, Lu Chang, Gaige Cai, Baihao Liu, Chenyu Duan, Mengwei Peng, Yong Wang, Kehong School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing210094 China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology China

High crack susceptibility remains a critical challenge in laser powder bed fusion of nickel-based superalloys with high γ'-volume fractions. This study systematically analyzes the crack formation mechanisms, melt pool morphology, and microstructural evolution of CM247LC alloy by optimizing selective laser re-melting (SLRM) parameters (laser power: 176 W, scan speed: 1143 mm/s, hatch spacing: 0.11 mm) combined with hot isostatic pressing (HIP: 1240 °C/150 MPa/4 h) and heat treatment (HT: 1260 °C solution treatment +870 °C aging). Results indicate that cracks primarily propagate along high-angle grain boundaries, with initiation closely linked to elemental segregation (O, Al, C, Ti) and residual stress concentration. Increasing the re-melting volumetric energy density (Ev) to 56.8 J/mm3 significantly enhances the melt pool depth-to-width ratio (D/W = 0.62), exacerbating temperature gradients and stress concentrations, thereby elevating crack susceptibility. After SLRM + HIP + HT treatment, the grain aspect ratio decreases from 7.32 to 3.66, while serrated grain boundaries and uniformly distributed γ'-phases effectively inhibit crack propagation and reduce residual stress. The final specimens exhibit exceptional strength-ductility synergy: ultimate tensile strength of 1352 ± 16 MPa, yield strength of 988 ± 25 MPa, and elongation of 11.5 ± 0.8 %, representing improvements of 23.0 %, 18.9 %, and 79.7 %, respectively, compared to the as-built selective laser melting samples. © 2025

关键词： Hot isostatic pressing

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Influence of the cathode position on beam current characteristics in the thermionic electron gun

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Radiation Detection technology and Methods 2022年第3期6卷 401-408页

作者： Jikang Fan Jian Zhang Haiying Xu Yong Peng Xinghua Sang Qi Zhou Kehong Wang Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Nanjing University of Science and TechnologyNanjing 210094China Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024China Technology Research Center Huaheng Welding Co.LtdKunshan 215300China

Purpose The research focuses on the simulation of inﬂuence of cathode positions on beam current characteristics in the thermionic electron *** The electricﬁeld distribution,bias voltage range and electron beam quality under different cathode positions were simulated by CST *** Changes in the cathode position can cause changes in the electricﬁeld distributions under the cathode emission surface change,thereby changing the size of the effective emitting area and affecting the relationship between the bias voltage and beam *** Only when the cathode is installed in the proper positions,the beam current and the bias voltage have an approximately linear proportional *** the cathode is installed improperly,the electron beam emission is disordered,resulting in decreased electron beam quality.

关键词： Simulation Thermionic electron gun Cathode position Beam current characteristics

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Microstructural evolution and mechanical property enhancement: Thin-walled structures of an Inconel 718 superalloy fabricated via hybrid laser–arc directed energy deposition

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Materials Science and Engineering: A 2025年 940卷

作者： Zhang, Wei Piao, Chengzhu Cai, Baihao Gao, Pengfei Chen, Zhenwen Liu, Chenyu Duan, Mengwei Kong, Jian Wang, Kehong Peng, Yong School of Materials Science and Engineering Nanjing University of Science and Technology Jiangsu Nanjing210094 China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Nanjing University of Science and Technology Jiangsu Nanjing210094 China National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology Baotou014030 China

arc-directed energy deposition (arc-DED) of the Inconel 718 (IN718) superalloy offers distinct advantages, such as low cost and high deposition efficiency. However, these methods are plagued by problems such as poor forming accuracy, coarse microstructures, and suboptimal mechanical properties. This study introduces a laser beam as an auxiliary heat source for the arc, seeking to present a novel approach to fabricate high-performance thin-walled structures of the IN718 superalloy. By contrasting the effects of arc-DED and hybrid laser–arc directed energy deposition (HLA-DED) on the fabrication of thin-walled IN718 superalloy components, we find that HLA-DED technology significantly improves the forming accuracy, refines the microstructure, and enhances the mechanical properties of thin-walled structures. Specifically, compared with arc-DED, the thin walls produced by HLA-DED show an 18.39 % increase in the effective width coefficient and a 59.13 % reduction in the machining allowance. Additionally, the significantly large heat input in HLA-DED expands the remelting region, leading to a higher microhardness of the samples. Prolonged in situ heat treatment during HLA-DED promotes the dissolution of Laves phases (950 °C) and subsequent precipitation of γ″ strengthening phases and MC carbides (650 °C). These improvements significantly enhance both the strength and plasticity of the IN718 superalloy components fabricated via HLA-DED. As a result, compared with the arc-DED samples, the HLA-DED samples exhibit superior yield strength, ultimate tensile strength and elongation in both the horizontal and vertical directions. © 2025 Elsevier B.V.

关键词： Tensile strength

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Microstructure Evolution and Mechanical Properties of Tic/Ti6al4v Composites Formed by Selective Laser Melting

SSRN

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SSRN 2024年

作者： Ou, Yangling Zhou, Qi Ma, Zhanlin Nanjing University of Science and Technology School of Materials Science and Engineering Nanjing210094 China The Key Laboratory of Controlled Arc Intelligent Additive Technology Ministry of Industry and Information Technology Nanjing University of Science and Technology Jiangsu Nanjing210094 China

TiC/Ti6Al4V composites were fabricated using selective laser melting (SLM). The effects of different process parameters on the density, microstructure and tensile properties of TiC/Ti6Al4V composites were analyzed. The findings revealed that a laser power is 180W and scanning speed of 1000mm/s resulted in TiC/Ti6Al4V composites density of up to 99.7%. The microstructure of TiC/Ti6Al4V composites primarily consisted of acicular α' martensite, unmelted carbon particles and in-situ TiC phase. As the laser energy density increased, the morphology of the TiC enhanced phase transitioned form nanometer-sized granules to micron-sized dendritic phase. This transformation was mainly attributed to the accumulation effect of laser energy and the size effect of carbon particles. When the laser energy density is 133J/mm3, the TiC/Ti6Al4V composites achieved maximum average microhardness and tensile strength values of are 461HV and 1367MPa, respectively. Compared to the Ti6Al4V alloy, the average microhardness exhibited an increase of approximately 34%, while the tensile strength grew by around 15%. These results underscored the effectiveness of TiC formation in enhancing the mechanical properties of the composite. Furthermore, the dissolution degree of carbon particles also indirectly dominated the strength and microhardness of the composite. © 2024, The Authors. All rights reserved.

关键词： Microstructure

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Microstructure Evolution and Mechanical Properties of Tic/Ti6al4v Composites Formed by Selective Laser Melting

SSRN

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SSRN 2023年

作者： Ou, Yangling Zhou, Qi Ma, Zhanlin Wang, Kehong Nanjing University of Science and Technology School of Materials Science and Engineering Nanjing210094 China The Key Laboratory of Controlled Arc Intelligent Additive Technology Ministry of Industry and Information Technology Nanjing University of Science and Technology Jiangsu Nanjing210094 China

The TiC/Ti6Al4V composites were prepared by selective laser melting (SLM). The effects of different process parameters on the density, microstructure and tensile properties of TiC/Ti6Al4V composites were analyzed. The results demonstrated that the density of TiC/Ti6Al4V composites could reach 99.7% under the optimal parameters, and the microstructure of TiC/Ti6Al4V composites was mainly composed of acicular α' martensite, unmelted carbon particles and in-situ TiC phase. With the increase of laser energy density, the morphology of TiC enhanced phase formed by in-situ reaction changed from nanometer granular to micron dendritic phase, which was mainly related to the accumulation effect of laser energy and the size effect of carbon particles. When the laser energy density is 133J/mm3, the maximum average microhardness and tensile strength of TiC/Ti6Al4V composites are 461HV and 1367MPa, respectively. Compared with Ti6Al4V alloy, the average microhardness was increased by about 34%, and the tensile strength is increased by about 15%. The results show that TiC formed in the matrix could effectively improve the mechanical properties of the composite. In addition, the dissolution degree of carbon particles also indirectly dominated the strength and microhardness of the composite. © 2023, The Authors. All rights reserved.

关键词： Microstructure

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In-Situ Reinforced Ti6al4v-Tib2 Titanium Matrix Composite Fabricated by Selective Laser Melting: Microstructure, Mechanical Properties and Heat Treatment

SSRN

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SSRN 2024年

作者： Li, Yinan Fang, Weiping Guo, Shun Duan, Mengwei Luo, Bingbing Li, Youkun Liu, Jie Gu, Jieren Peng, Yong Zhou, Qi Wang, Kehong School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing210094 China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Ministry of Industry and Information Technology Nanjing210094 China China-Ukraine Institute of Welding Guangdong Academy of Sciences Guangzhou510650 China

Ti6Al4V-x wt.%TiB2 titanium matrix composites (x=0, 0.01, 1, 3.4, 4.8) were prepared by selective laser melting (SLM), followed by solution-aging treatment. The microstructure and mechanical properties of the SLM-formed samples and the heat-treated ones were systematically investigated. In the SLM-formed samples, in-situ TiB whiskers clustered around the original position of the TiB2 particles, which reacted with the matrix through dissolution. The morphology and the distribution of TiB could be explained by the established transformation model of microstructure. The phase transformation of α′→α + β and the coarsening of TiB whiskers occurred during solution-aging treatment. The microhardness of the samples was enhanced with the increase of TiB2, while the heat treatment was harmful to microhardness. The fine grain strengthening and the dispersion strengthening caused by TiB whiskers enhanced the quasi-static compressive strength of the samples while the plasticity decreased. The samples were modified successfully by solution-aging, and the compressive strength and strain of the Ti6Al4V-0.01wt.%TiB2 composite reached 1957MPa and 23.7% respectively. The samples had higher ductility but lower strength under dynamic load, and the heat treatment had little effect on the dynamic properties in this work. © 2024, The Authors. All rights reserved.

关键词： Selective laser melting

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Study on Microstructure and Mechanical Properties of Cmt+P additive Manufactured Bainite Steel

SSRN

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SSRN 2023年

作者： Chai, Quanying Ren, Yan Peng, Yong Gu, Jieren School of Materials Science and Engineering Nanjing University of Science and Technology Nanjing210094 China Key Laboratory of Controlled Arc Intelligent Additive Manufacturing Technology Ministry of Industry and Information Technology Nanjing210094 China Beijing North Vehicle Group Corporation Quanying Beijing100072 China

In the materials processing industry regarding bainitic steels. This is due to their exceptional mechanical properties, which makes them highly desirable. To ensure their widespread application, the rapid and efficient additive manufacturing of high-performance bainitic steels is essential. This study proposes a novel technique for cold metal transition and pulsed composite arc technology(CMT+P) additive manufacturing of a bainitic alloy steel component. The mechanical properties and microstructure of the manufactured components are also thoroughly investigated. The study reveals that the microstructure of the bainitic steel component is primarily constituted of granular bainite, residual austenite, and M-A constituents. Due to the different cooling speeds, the main morphology of the top structure is different, and the bottom structure grain is smaller. The bainitic steel members displayed an overall average hardness of 345.2 HV, an average tensile strength of 1041.1 MPa, and an average elongation of 13.9%. The anisotropy was low, and the deposition direction showed a higher tensile strength, elongation, and impact absorption work than the lap direction. © 2023, The Authors. All rights reserved.

关键词： Microstructure

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A Novel Preparation Approach of Aluminum-Based Functionally Graded Material: Auxiliary Wire Filling Gas Metal arc Directed Energy Deposition

SSRN

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SSRN 2024年

作者： Yu, Tianjian Qiang, Wei Lu, Hao Li, Pengyuan Wang, Tianze Chao, Yaojie School of Material Science and Engineering Xi’an Shiyou University Xi’an710065 China Key Laboratory of Controlled Arc Intelligent Additive Technology Ministry of Industry and Information Technology Nanjing University of Science and Technology Nanjing210094 China Beijing Advanced Innovation Center for Materials Genome Engineering State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing100083 China Dalian Changfeng Industrial Corporation Dalian116038 China

The 2319-1100 aluminum-based functionally graded material (FGM) with continuous gradient transition interface was fabricated by auxiliary wire filling gas metal arc directed energy deposition (AWF-GMA-DED) process via changing the auxiliary wire ER1100 feeding speed. The droplet transfer behavior of the main wire and auxiliary wire, deposition morphology, and evolution law of microstructure and mechanical properties of the gradient wall were analyzed. The results indicate that with the increase of the auxiliary wire ER1100 feeding speed, the transition process of the auxiliary wire droplet transfer mode is large droplet transfer—bridge transfer—continuous transfer, and the main wire ER2319 droplet transfer is stable and not affected by the auxiliary wire ER1100. At the same time, the bimetallic single deposition layer height and contact angle increase, and the penetration depth and area of the base metal penetration zone decrease. The 2319-1100 aluminum-based FGM prepared by auxiliary wire filling GMA additive manufacturing has good formation and free of defects. As the filling ratio of ER1100 increases, the area of interlayer equiaxed grain band and equiaxed grain size increases gradually, the continuity of eutectic structure at the grain boundary is weakened, and the eutectic structure is refined. When the ER1100 filling ratio increases from 0% to 35%, the microhardness decreases by 25.72 HV (29.1%), and the tensile strength only decreases by 21.46 MPa (8.77%). However, the elongation increases from 11.89% to 19.41%, and the corrosion resistance of the material also improves. © 2024, The Authors. All rights reserved.

关键词： Filling

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