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Hot rolling and annealing effects on the microstructure and mechanical properties of ODS austenitic steel fabricated by electron beam selective melting

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Frontiers of Materials Science 2016年第1期10卷 73-79页

作者： Rui GAO Wen-jun GE Shu MIAO Tao ZHANG Xian-ping WANG Qian-feng FANG Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei 230031 China Department of Mechanical Engineering Tsinghua University Beijing 100084 China

The grain morphology, nano-oxide particles and mechanical properties of oxide dispersion strengthened （ODS）-316L austenitic steel synthesized by electron beam selective melting （EBSM） technique with different post-working processes, were explored in this study. The ODS-316L austenitic steel with superfine nano-sized oxide particles of 30-40 nm exhibits good tensile strength （412 MPa） and large total elongation （about 51%） due to the pinning effect of uniform distributed oxide particles on dislocations. After hot rolling, the specimen exhibits a higher tensile strength of 482 MPa, but the elongation decreases to 31.8% owing to the introduction of high-density dislocations. The subsequent heat treatment eliminates the grain defects induced by hot rolling and increases the randomly orientated grains, which further improves the strength and ductility of EBSM ODS-316L steel.

关键词： electron beam selective melting ODS.316L steel powder hot rolling microstructure tensile strength

Scan Strategy in electron beam selective melting

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Tsinghua Science and Technology 2009年第S1期14卷 120-126页

作者：陆伟林峰韩建栋齐海波晏耐生 Department of Mechanical Engineering Tsinghua University

In electron beam selective melting process, powder pushed-away phenomena and uneven temperature field are two main obstacles, which are greatly associated with the electron beam scan mode. In this paper, various scan strategies, including iterative scan mode, reverse scan mode, interlaced reverse scan mode, randomized block scan mode, and constant length scan mode, are investigated. The analyses for each scan strategy are presented based on the influence to the temperature field over the formation zone and the powder pushed-away phenomena. The most promising strategy, interlaced reverse scan mode, is approved by the ANSYS simulation and a two-dimensional scan experiment. The result shows interlaced reverse scan mode can improve the uniformity of the temperature field and reduce the powder pushed-away phenomena.

关键词： scan strategy electron beam selective melting powder pushed-away

Performance of Ti6Al4V fabricated by electron beam and laser hybrid preheating and selective melting strategy

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China Foundry 2021年第4期18卷 351-359页

作者： Mo-han Hao Lei Zhang Bin Zhou Hong-xin Li Ming-zhi Li Feng Lin Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China

electron beam selective melting(EBM)and selective laser melting(SLM)are regarded as significant manufacturing processes for near-net-shaped Ti6Al4V ***,in the conventional EBM process,preheating is necessitated to avoid"smoke"caused by the charging of *** the conventional SLM process,laser as an energy source without the risk of"smoke"can be employed to melt metal powder at low ***,because of the low absorption rate of laser,the powder bed temperature cannot reach a high *** is difficult to obtain as-built TiAl4V with favorable comprehensive properties via conventional EBM or ***,two types of electron beam and laser hybrid preheating(EB-LHP)combined with selective melting strategies are *** laser to preheat powder allows EBM to be performed at a low powder bed temperature(EBM-LT),whereas using an electron beam to preheat powder allows SLM to be performed at a high powder bed temperature(SLM-HT).Ti6Al4V samples are fabricated using two different manufacturing strategies(i.e.,EBM-LT and SLM-HT)and two conventional processes,i.e.,EBM at a high powder bed temperature(EBM-HT)and SLM at a low powder bed temperature(SLM-LT).The temperature-dependent surface quality,microstructure,density,and mechanical properties of the as-built Ti6Al4V samples are characterized and *** show that EBM-LT Ti6Al4V exhibits a higher ultimate tensile strength(981±43 MPa)and a lower elongation(12.2%±2.3%)than EBM-HT Ti6Al4V owing to the presence ofα′*** SLM-HT Ti6Al4V possesses the highest ultimate tensile strength(1,059±62 MPa)and an elongation(14.8%±4.0%)comparable to that of the EBM-HT Ti6Al4V(16.6%±1.2%).

关键词： Ti6Al4V electron beam selective melting selective laser melting hybrid preheating

Additive Manufacturing of Nickel-Based Superalloy Single Crystals with IN-738 Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第3期35卷 369-374页

作者： Yang Li Ye-Feng Yu Zhi-Bin Wang Xiao-Yu Liang Wen-Bin Kan Feng Lin Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Key Laboratory for Advanced Materials Processing Technology Ministry of Education of ChinaBeijing 100084China Bio-Manufacturing and Rapid Forming Technology Key Laboratory of Beijing Beijing 100084China

The production of non-weldable nickel-based superalloys,especially single-crystal superalloys,is important for additive ***-crystal specimens of non-weldable nickel-based superalloys were produced by electron beam selective melting using an IN-738 *** this study,single-crystal nickel-based superalloy specimens of diff erent sizes were prepared by a multiple preheating process and tight control of the melting parameters without the need for a grain selector or single-crystal seed for the first *** backscattered diff raction measurements were performed to confi rm the presence of a single *** transition boundaries between the polycrystalline and single-crystal regions at the edges and bottom of the samples were characterized to analyze the formation of single crystals.

关键词： Non-weldable superalloys electron beam selective melting Single crystal Grain selection