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Journal of Materials Science & Technology 2023年第23期154卷 30-42页

作者： Qiao Zhong Kaiwen Wei Taoyuan Ouyang Xiangyou Li Xiaoyan Zeng Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 China Beijing Research Institute of Telemetry Beijing 100076 China

Rotation angle of the laser scan direction between two adjacent layers is a key controlling parameter during the high-power (≥ 1 kW) laser powder bed fusion (HP-LPBF) process. This study investigates the influences of rotation angles (θ = 0°, 45°, 90°, 105°) on the surface morphology, microstructure, and mechanical properties of inconel 718 (IN718) alloy produced by HP-LPBF. Results show that adopting low rotation angles (e.g., 0° and 45°) is prone to relatively poor surface finish and lack-of-fusion defects, whereas adopting high rotation angles (e.g., 90° and 105°) induces smaller surface roughness and better relative density. Each case reveals a noticeable edge effect but the maximal heights witness a downward trend with the increase of rotation angle. There are some minor differences in the primary dendrite arm spacing and grain morphology by varying the rotation angles. Moreover, the tensile property is slightly enhanced as the rotation angle increases. The present work suggests that high rotation angles like 90° and 105° would probably be more favorable for the 1 kW HP-LPBF process than rotation angles with relatively low values.

关键词： High-power laser powder bed fusion Rotation angle Surface morphology Microstructure Mechanical properties inconel 718 alloy

Mechanical and microstructural characterization of additive manufactured inconel 718 alloy by selective laser melting and laser metal deposition

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Journal of Iron and Steel Research International 2022年第8期29卷 1322-1333页

作者： Fa-yun Lu Hong-yuan Wan Xin Ren Li-ming Huang Hai-lin Liu Xin Yi Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China

The direct comparison of the microstructure and tensile properties of inconel 718 fabricated by selective laser melting (SLM) or laser metal deposition (LMD) has been carried out. In the as-built state, LMD-fabricated specimens show lower tensile yield strength and fracture elongation than SLM-fabricated specimens due to the coarser solidification microstructure, including grains, cellular dendrites and Laves phases. This is mainly because the cooling rate of the LMD process is 2 to 3 orders lower than that of the SLM process. Upon the same heat treatment, both yield strengths of SLMand LMD-fabricated specimens are enhanced significantly. Notably, LMD-fabricated specimens exhibit simultaneous improvement in the strength and ductility, which is mainly attributed to the presence of small granular Laves phases and uniformly distributed nanoscale c00 strengthening phases. The results could serve as a guidance for selecting suitable postheat treatment routes for specific additive manufacturing process to attain excellent strength-ductility synergy.

关键词： inconel 718 alloy Selective laser melting Laser metal deposition Heat treatment Strength-ductility synergy

Orientational growth behavior and mechanism of delta(δ)phase precipitation in cold-rolled inconel 718 alloy during heat treatment

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Journal of Iron and Steel Research International 2024年第1期31卷 264-274页

作者： Neng-yong Ye Guang-liang Zhang Tian-yue Huang Ming Cheng Shi-hong Zhang Lei Wang School of Materials Science&Engineering Taizhou UniversityTaizhou318000ZhejiangChina Institute of Metal Research Chinese Academy of SciencesShenyang110016LiaoningChina

Due to the important role ofδphase's quantity and morphology in the mechanical and fatigue properties of inconel 718 alloy and its components,it is necessary to renew insights into the effect of cold deformation on theδphase precipitation,especially on the morphology ***,the nucleation and growth behavior ofδphase in cold-rolled inconel 718 alloy during aging were *** results show that the precipitation rate and volume fraction ofδphase increase with increasing the cold rolling reduction from 10%to 50%.The volume fraction ofδphase reaches equilibrium after 5 h,remaining at 5.98%,6.52%,and 6.79%under different rolling reductions(10%,30%,and 50%),*** nucleation ofδphase mainly occurs on different sites(grain boundaries,new twin boundaries and old twin boundaries)under 10%rolling reduction,whileδphase mainly nucleates on the new grain boundaries of static recrystallization due to 50%rolling *** the growth ofδphase undergoes a process of alternate orientation growth from spherical(nucleation)→short rod(longitudinal orientation growth)→short rod(radial orientation growth)→dynamic *** 10%rolling reduction,δphase tends to grow into the matrix,while under 50%rolling reduction,the orientation grows faster and is easily affected by the grain boundary curvature.

关键词： inconel 718 alloy Cold rolling δphase Orientation growth Morphology evolution

Effect of two-step solid solution on microstructure andδphase precipitation of inconel 718 alloy

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International Journal of Minerals,Metallurgy and Materials 2024年第10期31卷 2199-2207页

作者： Enyu Liu Qingshuang Ma Xintong Li Aoxue Gao Jing Bai Liming Yu Qiuzhi Gao Huijun Li School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Resources and Materials Northeastern University at QinhuangdaoQinhuangdao 066004China School of Materials Science&Engineering Tianjin UniversityTianjin 300354China School of Mechanical Materials and Mechatronic EngineeringUniversity of WollongongWollongongNSW 2522Australia

inconel 718 is the most popular nickel-based superalloy and is extensively used in aerospace,automotive,and energy indus-tries owing to its extraordinary thermomechanical *** effects of different two-step solid solution treatments on microstructure andδphase precipitation of inconel 718 alloy were studied,and the transformation mechanism fromγ″metastable phase toδphase was *** precipitates were statistically analyzed by X-ray *** results show that theδphase content firstly increased,and then decreased with the temperature of the second-step solid *** changes in microstructure andδphase were studied by scanning electron microscopy and transmission electron *** intragranularδphase formed in inconel 718 alloy at the second-[100]_(δ)[011]γ step solid solution temperature of 925℃,and its orientation relationship withγmatrix was determined as//and(010)_(δ)//(111)γ.Furthermore,the Vickers hardness of different heat treatment samples was measured,and the sample treated by second-step solid solution at 1010℃ reached the maximum hardness of HV 446.84.

关键词： inconel 718 alloy two-step solid solution treatment δphase γ″-δtransformation

Influence of magnetically constricted arc traverse speed (MCATS) on tensile properties and microstructural characteristics of welded inconel 718 alloy sheets

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Defence Technology（防务技术） 2021年第4期17卷 1395-1413页

作者： Tushar Sonar Visvalingam Balasubramanian Sudersanan Malarvizhi Thiruvenkatam Venkateswaran Dhenuvakonda Sivakumar Centre for Materials Joining and Research(CEMAJOR) Department of Manufacturing EngineeringAnnamalai UniversityAnnamalai Nagar608002Tamilnadu StateIndia Heat Treatment and Welding Metallurgy Division(HWMD) Materials and Metallurgy Group(MMG)Vikram Sarabhai Space Centre(VSSC)ISROThiruvananthpuram695022Kerala StateIndia

The magnetically constricted arc technique was implemented to mitigate the heat input related metallurgical problems in Gas Tungsten Arc Welding(GTAW)of inconel 718 alloy particularly Nb segregation and subsequent laves phase evolution in fusion *** paper reports the direct effect of magnetically constricted arc traverse speed(MCATS)on bead profile,tensile properties and microstructural evolution of inconel 718 alloy sheets joined by Gas Tungsten Constricted Arc Welding(GTCAW)*** mechanism amenable for the microstructural modification and corresponding influence on the tensile properties of joints is investigated both in qualitative and quantitative manner related to the mechanics of arc constriction and *** is correlated to the solidification conditions during *** relationship between MCATS and Arc Constriction Current(ACC)was *** interaction effect on the magnetic arc constriction and joint performance was *** showed that the joints fabricated using CATS of 70 mm/min exhibited superior tensile properties(98.39% of base metal strength with 31.50% elongation).It is attributed to the grain refinement in fusion zone microstructure leading to the evolution of finer,discrete laves phase in interdendritic areas.

关键词： GTCA welding inconel 718 alloy Magnetically constricted arc traverse speed Tensile properties Microstructure Laves phase

Effects of current path on structure and segregation during electroslag remelting process of inconel 718 alloy with same power input

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Journal of Iron and Steel Research International 2021年第12期28卷 1574-1581页

作者： Fu-bin Liu Hai-bo Cao Hua-bing Li Zhou-hua Jiang Xin Geng School of Metallurgy Northeastern UniversityShenyang110819LiaoningChina Key Laboratory of Neutronics and Radiation Safety Institute of Nuclear Energy Safety TechnologyChinese Academy of SciencesHefei230031AnhuiChina State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819LiaoningChina

Current-conductive mold was recently developed to extend electroslag remelting(ESR)functions to overcome some solidification defects by changing the current *** macrostructures,microstructures,macrosegregation,and microsegregation of the inconel 718 ingots produced by the custom laboratory-scale ESR furnace under different current paths(the classical ESR and the single power,and two circuits ESR process with current-conductive mold(ESR-STCCM))with the same power input were compared and *** results indicate that when the ingot was produced during ESR and ESR-STCCM processes,at the same power input,the pool depth was 104 and 90 mm,respectively.A flatter and shallower molten pool was obtained during ESR-STCCM ***,compared with a classical ESR ingot,the cooling rate of the centerline of ESR-STCCM ingot was increased from 12.7 to 16.7 K min^(−1).The increased cooling rates caused by decreased melting rate and thinner slag skin reduced the growth angle of columnar crystal to the vertical axis and the secondary dendrite arm ***,the macrosegregation and microsegregation of segregation elements for ESR-STCCM process were dramatically reduced compared with ESR *** average volume fraction of Laves phase was reduced from 7.39%to 6.14%,and the segregation of Nb in Laves phase was significantly reduced.

关键词： Electroslag remelting Current path Structure Segregation inconel 718 alloy Current-conductive mold

Strain-induced Precipitation Behavior ofδPhase in inconel 718 alloy

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Journal of Iron and Steel Research International 2014年第3期21卷 375-381页

作者： Xian-ping WEI Wen-jie ZHENG Zhi-gang SONG Ting LEI Qi-long YONG Qing-cheng XIE Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology Central Iron and Steel Research Institute No.704 Institute of China Shipbuilding Industry Corporation

To study the precipitation dynamics of 3 phase in inconel 718 alloy, two-stage interrupted compression method was used in the region of cold deformation temperatures and the temperatures range from 875 to 975 ℃. The precipitation-time-temperature （PTT） curve of 3 phase was obtained by analyzing the softening kinetics curves. For verifying the type of the precipitates and confirming the validity of the test, the transmission electron microscopy （TEM）, scanning transmission electron microscopy （STEM） and energy dispersion spectrum （EDS） were em- ployed. Experimental results indicated that the PTT curve for 3 precipitation exhibited a typical ＂C＂ shape and the nose points of start and finish precipitation were about 5 s at 920 ℃ and 2 815 s at 940 ℃, respectively. In addition, the nucleation of δ was heterogeneous. The nucleation sites varied with temperatures, including dislocation, grain boundary and stacking fault within γ″ phase. And 3 particles grew quickly at higher temperature with lower density. Moreover, the driving force of nucleation was mainly including chemical free energy, interracial energy and disloca- tion distorted energy. And the dislocation distorted energy could decide the density of nucleation in the strain-induced process.

关键词： inconel 718 alloy strain-induced precipitation cold deformation nucleation site

Effects of Carbon Content on Mechanical Properties of inconel 718 alloy

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Journal of Iron and Steel Research International 2015年第1期22卷 78-83页

作者： Wen-jie ZHENG Xian-ping WEI Zhi-gang SONG Qi-long YONG Han FENG Qing-cheng XIE Central Iron and Steel Research Institute Materials Research Center Dong Fang Steam Turbine Works No.704 Institute of China Shipbuilding Industry Corporation

For improving the service performance of inconel 718 alloy, especially used as a corrosion-resistant alloy for special environment, the microstructure and mechanical property of different carbon-containing inconel 718 alloys were investigated by the Thermo-Calc software and experiments. The experimental results indicated that the mor- phology, distribution and types of carbides mainly existing in the form of MC＇were hardly influenced by solution treatment at 1050 ℃ for 1 h. The precipitation amount and particle size of carbides decreased with the decrease of carbon content, which was the main reason resulting in the increase of ductility and toughness. In addition, moving dislocation could be restrained by the precipitation of carbides. Therefore, the strength could benefit from the precip- itation strengthening of carbides when the precipitation of γ′/γ″ phase was not influenced by the precipitation of carbides.

关键词： inconel 718 alloy microstructure carbide mechanical property precipitation strengthening

Microstructural characterization of inconel 718 alloy after pulsed laser surface treatment at different powers

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Transactions of Nonferrous Metals Society of China 2018年第8期28卷 1530-1537页

作者： Lin-jiang CHAI Shan-shan YUAN Wei-jiu HUANG Xu-sheng YANG Fang-jun WANG Dong-zhe WANG Jun-jun WANG College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China Chongqing Materials Research Institute Co. Ltd.Chongqing 400707China

An annealed inconel 718 alloy was surface-treated by pulsed laser at three different powers（100, 50 and 25 W）. Microstructural changes induced by the laser treatments were characterized by use of electron backscatter diffraction and electron channeling contrast imaging techniques. Results show that both annealing twins and strengthening precipitates profusely existing in the as-received specimen are dissolved at elevated temperatures during the laser irradiation. Meanwhile, in the melting zone（MZ）, densities of low angle boundaries（LABs） are greatly increased with a large number of Laves phases preferentially distributed along such LABs. For different specimens, widths and depths of their MZs are found to be gradually reduced with decreasing the laser powers. Orientation analyses reveal that the columnar grains in the MZ of the 100 W specimen could inherit orientations existing in the matrix while lower laser powers promote the formation of more nuclei with scattered orientations to grow to be granular grains in the MZ. Hardness tests reveal that the MZs of all laser-treated specimens are softer than the matrix probably due to both precipitate dissolution and grain coarsening.

关键词： inconel 718 alloy grain boundaries pulsed laser surface treatment electron backscatter diffraction harchless

KINETICS OF δ PHASE PRECIPITATION IN COLD ROLLED inconel 718 alloy

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Chinese Journal of Aeronautics 1997年第3期10卷 54-57页

作者： Liu Wenchang, Yao Mei (Yanshan University, Qinhuangdao, China, 066004) Liu Runguang (Harbin Institute of Technology, Harbin, China, 150001) Chen Zonglin, Jiang Zhaoqun, Wang Shaogang (Shenyang Liming Engine Manufacturing Company, Shenyang, C

The volume fraction of δ phase in cold rolled inconel 718 alloy aged at 910℃ for different times is measured by X ray diffraction techniques, and the influence of cold rolling on the kinetics of δ phase precipitation is investigated. It has been found that the relation between the volume fraction of δ phase and aging time follows the Avrami equation. With increasing cold rolling reduction, the value of n decreases and the value of a increases.

关键词： cold rolling precipitation (chemistry) kinetics inconel 718 alloy δ phase