Abstract：The mass percent of carbon in GH3625 alloy is about 0.05%. Because of the high content of Nb, Mo and Cr, carbides of MC, M6C and M23C6 type will be formed in the alloy, and carbide segregation will easily occur due to the selective crystallization during solidification. Because of high redissolution temperature, carbide is difficult to eliminate in the wrought temperature range, which will lead to the problem of carbide banded aggregation in alloy bars and have a great influence on its service performance. Thermodynamic software of Thermal-calc was used to calculate and analyze the equilibrium precipitated phase and precipitation law of primary carbide in GH3625 alloy. The effect of Mg on the morphology, size and distribution of primary carbide in GH3625 alloy was studied by metallographic microscope and scanning electron microscope. The results show that the matrix of GH3625 alloy is a single austenite phase, and MC carbide, as a high temperature precipitated phase, precipitates directly from the liquid phase, which is rich in Nb, followed by a small amount of Ti, Mo and other elements. With the decrease of solidification temperature, the mass percent of Nb gradually increases. When Mg is not added, a large number of strip-shaped primary carbides are precipitated between secondary dendrites in GH3625 alloy, and their average diameter and area are large. After adding 0.014% Mg, Mg not only improves the distribution and morphology of carbides at interdendritic and grain boundary, but also reduces the size of primary carbides by changing the specific interfacial energy relationship between carbide phase and matrix phase. When the mass percent of Mg increases to 0.037%, the distribution of primary carbides is more uniform and dispersed, and the effect of refining and spheroidizing carbides by Mg is the best. At the same time, under the conditions of water cooling and air cooling, the cooling rate of experimental alloy is higher than that of furnace cooling, and the size of primary carbide precipitation is relatively smaller.
张红亮, 龚伟, 姜周华, 王鹏飞. 镁对GH3625合金一次碳化物析出的影响[J]. 钢铁, 2022, 57(9): 148-155.
ZHANG Hong-liang, GONG Wei, JIANG Zhou-hua, WANG Peng-fei. Effect of magnesium on precipitation of primary carbide in GH3625 alloy[J]. Iron and Steel, 2022, 57(9): 148-155.
[1] 李红梅,聂义宏,张鑫,等. 均匀化处理对铸态GH625合金组织的影响[J]. 材料热处理学报,2019,40(3):75.(LI Hong-mei, NIE Yi-hong, ZHANG Xin,et al. Effects of homogenization treatment on microstructure of as-cast GH625 alloy[J]. Transactions of Materials and Heat Treatment. 2019,40(3):75.) [2] 王志刚,杨玉军,田水仙,等. 冷拔变形对GH3625合金组织和性能的影响[J]. 钢铁研究学报,2011,23(增刊2):92.(WANG Zhi-gang,YANG Yu-jun,TIAN Shui-xian,et al. Influence of cold drawing process on microstructures and tensile properties of alloy GH3625[J]. Journal of Iron and Steel Research,2011,23(s2):92.) [3] 丁雨田,豆正义,高钰璧,等. 均匀化态GH3625合金熔化和凝固过程中的相变[J]. 材料研究学报,2017,31(11):853.(DING Yu-tian,DOU Zheng-yi,GAO Yu-bi,et al. Phase transformation during metling and solidifying process of homogenized superalloy GH3625[J]. Chinese Journal of Materials Research,2017,31(11):853.) [4] Kontis P,Mohd Yusof H A,Pedrazzini S,et al. On the effect of boron on grain boundary character in a new polycrystalline superalloy[J]. Acta Materialia,2015,103:688. [5] 孙满意,谭毅,王以霖,等. 电子束熔炼对高速钢碳化物的影响[J]. 钢铁,2021,56(3):103.(SUN Man-yi,TAN Yi,WANG Yi-lin,et al. Effect of electron beam melting on carbide of high speed steel[J]. Iron and Steel,2021,56(3):103.) [6] 曹小军, 李明林, 黄宇,等. Nb-H13钢中一次碳化物的析出机理和控制[J]. 中国冶金, 2020, 30(3): 21. (CAO Xiao-jun, LI Ming-lin, HUANG Yu, et al. Precipitation mechanism and improvement of primary carbide in Nb-H13 steel[J]. China Metallurgy, 2020, 30(3): 21.) [7] 刘军,陆青林,李铮,等. 轴承钢中微量镁改善碳化物作用机理研究[J]. 钢铁研究学报,2011,23(5):39.(LIU Jun,LU Qing-lin,LI Zheng,et al. Study on the mechanism of trace magnesium improving carbide in bearing steel[J]. Journal of Iron and Steel Research,2011,23(5):39.) [8] 杨健, 蔡文菁. 镁处理对钢中夹杂物以及HAZ组织和性能的影响[J]. 钢铁, 2021, 56(7): 13. (YANG Jian, CAI Wen-jing. Effect of magnesium treatment on inclusions and HAZ microstructure and properties of steel plate[J]. Iron and Steel, 2021, 56(7): 13.) [9] 孙立根, 雷鸣, 张鑫, 等. 镁处理对船体钢组织细化作用的高温原位分析[J]. 钢铁, 2020, 55(5): 94. (SUN Li-gen, LEI Ming, ZHANG Xin, et al. In-situ research on microstructure refining effect of Mg treatment for shipbuilding steel at high temperature[J]. Iron and Steel, 2020, 55(5): 94.) [10] 王林珠, 席作冰, 李长荣. 镁处理高碳硬线钢中夹杂物[J]. 钢铁, 2021, 56(7):56.(WANG Lin-zhu, XI Zuo-bing, LI Chang-rong. Inclusions in high-carbon hard wire steel treated by Mg[J]. Iron and Steel, 2021, 56(7): 56.) [11] LI Ji,LI Jing,WANG Liang-liang,et al. Study of the effect of trace mg additions on carbides in die steel H13[J]. Metal Science and Heat Treatment,2016,58:330. [12] Bor H Y,Chao C G,Ma C Y. The effects of Mg microaddition on the mechanical behavior and fracture mechanism of MAR-M247 superalloy at elevated temperatures[J]. Metallurgical and Materials Transactions A,1999,30:551. [13] PEI Zhong-ye,LI Jun-tao,ZHAO Ming-han,et al. Effect of magnesium and cerium microelement on microstructures and mechanical properties of K465 nickel-base superalloy[J]. Journal of Rare Earths,2007,25(9):373. [14] 常立忠,高岗,施晓芳,等. 镁对GCr15轴承钢中液析碳化物的影响[J]. 过程工程学报,2019,19(2):363.(CHANG Li-zhong,GAO Gang,SHI Xiao-fang,et al. Effect of magnesium on eutectic carbides in GCr15 bearing steel[J]. The Chinese Journal of Process Engineering,2019,19(2):363.) [15] CHANG L Z,GAO G,SHI X F. Effect of Mg-Re complex treatment on eutectic carbides in bearing steel[J]. Ironmaking and Steelmaking, 2020,47(1):59. [16] GAO B,SUI Y,WANG H,et al. Effects of cooling rate on the solidification and microstructure of nickel-based superalloy GTD222[J]. Materials,2019,12(12):1920. [17] 贺宝,李晶,史成斌,等. 电渣重熔过程冷却强度对含镁H13钢中碳化物的影响[J]. 工程科学学报,2016,38(12):1720.(HE Bao,LI Jing,SHI Cheng-bin,et al. Effect of cooling intensity on carbides in Mg-containing H13 steel during the electroslag remelting process[J]. Chinese Journal of Engineering,2016,38(12):1720.) [18] 谷雨,杨树峰,赵朋,等. 镍基高温合金GH4738的凝固偏析和碳化物析出行为[J]. 中国冶金,2021,31(7):13.(GU Yu, YANG Shu-feng,ZHAO Peng,et al. Solidification segregation and carbide precipitation behavior of nickel-based superalloy GH4738[J]. China Metallurgy,2021,31(7):13.) [19] Pines B J. On solid solutions I: The elastic sphere model as applied to solid solutions and deviations from Vegard's rule[J]. Journal of Physics-Ussr,1940,3:309. [20] 雍岐龙. 钢铁材料中的第二相[M]. 北京:冶金工业出版社,2006.(YONG Qi-long. The Second Phase in Iron and Steel[M].Beijing:Metallurgical Industry Press,2006.)
2022, Vol. 57 
