基于内聚力模型的白点萌生机理研究
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摘要
基于内聚力理论、氢压理论和应力作用下氢富集理论,在以往孔洞锻合研究的基础上,建立了白点萌生扩展的有限元分析模型。研究了初始氢浓度、裂纹长度以及多裂纹耦合作用等多种因素对白点萌生的影响,确定了不同条件下白点萌生的临界氢浓度及其变化趋势。结果表明,氢对白点萌生具有重要的影响,在白点萌生过程中,高浓度的氢聚集在裂纹端部,极大地降低了钢的内聚力强度;对于单裂纹,随着裂纹长度的增加,白点萌生的临界氢浓度逐渐减小并趋于稳定值;当多个密集小裂纹同时存在时,裂纹间的耦合效应会导致小裂纹有贯穿形成大裂纹的趋势,而远端裂纹的耦合效应则相对较小;对于多裂纹,白点萌生临界氢浓度具有随裂纹个数的增加而线性递减的趋势。
Based on the previous experimental studies,a finite element model of flake initiation was established.The theories of cohesive strength,hydrogen pressure and stress induced hydrogen diffusion were coupled in this model.The effects of hydrogen content,crack length and multi-crack coupling on flake formation were studied.Meanwhile,the critical hydrogen concentration and its changing trends for flake formation under different conditions were determined.The results show that hydrogen is of important effect on the initiation of flakes.During the process of flake formation,a high concentration of hydrogen was accumulated at the crack tip,which is greatly reduces the cohesive strength of steel.As for a single crack,the critical hydrogen concentration of the flake initiation gradually decreases and tends to a steady value with the crack length increasing.When a plurality of dense small cracks are present at the same time,the small cracks tend to form large cracks because of the effect of stress coupling,while the distal cracks has less influence on the flake initiation.For multiple cracks,the critical hydrogen concentration at the flake initiation tends to decrease linearly with the increase of the number of cracks.
Based on the previous experimental studies,a finite element model of flake initiation was established.The theories of cohesive strength,hydrogen pressure and stress induced hydrogen diffusion were coupled in this model.The effects of hydrogen content,crack length and multi-crack coupling on flake formation were studied.Meanwhile,the critical hydrogen concentration and its changing trends for flake formation under different conditions were determined.The results show that hydrogen is of important effect on the initiation of flakes.During the process of flake formation,a high concentration of hydrogen was accumulated at the crack tip,which is greatly reduces the cohesive strength of steel.As for a single crack,the critical hydrogen concentration of the flake initiation gradually decreases and tends to a steady value with the crack length increasing.When a plurality of dense small cracks are present at the same time,the small cracks tend to form large cracks because of the effect of stress coupling,while the distal cracks has less influence on the flake initiation.For multiple cracks,the critical hydrogen concentration at the flake initiation tends to decrease linearly with the increase of the number of cracks.
引文
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[14] 韦东滨,韩静涛,谢建新,等.热塑性变形条件下钢内部裂纹愈合的实验研究[J].金属学报,2000,36(6):622-625.(WEI Dong-bin,HAN Jing-tao,XIE Jian-xin,et al.Experimental study on inner crack healing in steel during hot plastic deforming[J].Acta Meta-llurgica Sinica,2000,36(6):622-625.(in Chinese))
[15] 唐鼎,张卿卿,方文利,等.基于空洞演化理论的挤压焊合描述模型[J].机械工程学报,2014,50(22):34-41.(TANG Ding,ZHANG Qing-qing,FANG Wen-li,et al.Modeling of the extrusion seam welding based on the void evolution[J].Journal of Mechanical Engineering,2014,50(22):34-41.(in Chinese))
[16] 刘文辉,刘龙飞,唐建国.FCC晶体中孔洞长大行为的研究[J].工程力学,2010,27(6):228-231,251.(LIU Wen-hui,LIU Long-fei,TANG Jian-guo.The study of void growth behavior in FCC crystal[J].Engineering Mechanics,2010,27(6):228-231,251.(in Chinese))
[17] 周航,孔纲强,曹兆虎,等.椭圆形孔扩张弹性分析[J].固体力学学报,2015,36(1):85-91.(ZHOU Hang,KONG Gang-qiang,CAO Zhao -hu,et al.Elastic analysis of elliptical cavity expansion[J].Chinese Journal of Solid Mechanics,2015,36(1):85-91.(in Chinese))
[18] 姜晶晶,林卓英,冯淼林,等.温度对Cr5 冷轧辊钢断裂韧度影响的试验研究[J].锻压技术,2012,37(4):135-139.(JIANG Jing-jing,LIN Zhuo -ying,FENG Miao -lin,et al.Experimental study on temperature influence to fracture toughness of Cr5 cold roll steel[J].Forging & Stamping Technology,2012,37(4):135-139.(in Chinese)
[2] 褚武扬,乔利杰,李金许,等.氢脆和应力腐蚀[M].北京:科学出版社,2013.(CHU Wu-yang,QIAO Li -jie,LI Jin-xu,et al.Hydrogen Embrittlement and Stress Corrosion Cracking[M].Beijing:Science Press,2013.(in Chinese))
[3] Yokobori A T,Kushida T,Ohmi T.The stress induced hydrogen diffusion behavior and the sensitivity of hydrogen embrittlement at the heat affected zone of weld part based on analytical solution [J].Journal of the Japan Institute of Metals,2006,70(6):489-494.
[4] Serebrinsky S,Carter E A,Ortiz M.A quantum mechanically informed continuum model of hydrogen embrittlement[J].Journal of the Mechanics and Physics of Solids,2004,52(10):2403-2430.
[5] Olden V,Thaulow C,Johnsen R,et al.Application of hydrogen influenced cohesive laws in the prediction of hydrogen-induced stress cracking in 25% Cr duplex stainless steel[J].Engineering Fracture Mechanics,2008,75(8):2333-2351.
[6] Scheider I,Pfuff M,Dietzel W.Simulation of hydrogen assisted stress corrosion cracking using the cohesive model[J].Engineering Fracture Mechanics,2008,75(15):4283-4291.
[7] 王艳飞,巩建鸣,蒋文春,等.基于内聚力模型的AISI4135高强钢氢致滞后断裂数值模拟[J].金属学报,2011,47(5):594-600.(WANG Yan-fei,GONG Jian-ming,JIANG Wen-chun,et al.Numerical simulation of hydrogen induced delayed fracture of AISI4135 high strength steel using cohesive zone modeling[J].Acta Metallurgica Sinica,2011,47(5):594-600.(in Chinese))
[8] de Kazinczy F.On the pressure of hydrogen in cavities of steel[J].Acta Metallurgica,1959,7(7):525-527.
[9] Phragmen G.On the relation between the hydrogen proportion in iron,the temperature and the hydrogen equilibrium pressure [J].Jemkontorets Ann,1944,128:537-553.
[10] Jiang D E,Carter E A.First principles assessment of ideal fracture energies of materials with mobile impurities:Implications for hydrogen embrittlement of metals [J].Acta Materialia,2004,52(16):4801-4807.
[11] Hondros E D,Seah M P.The theory of grain boundary segregation in terms of surface adsorption analogues[J].Metallurgical Transactions A,1977,8(9):1363-1371.
[12] van der Ven A,Ceder G.Impurity-induced van der Waals transition during decohesion [J].Physical Re -view B,2003,67(6):060101.
[13] 黄华贵,杜凤山,臧新良.大型零件M锻造法及其孔洞缺陷锻合过程的数值模拟[J].锻压技术,2005,30(s):34-37.(HUANG Hua-gui,DU Feng-shan,ZANG Xin-liang.Numerical simulation of bulk ingot upsetting and void fault closing with M method[J].Forging & Stamping Technology,2005,30(s):34-37.(in Chinese))
[14] 韦东滨,韩静涛,谢建新,等.热塑性变形条件下钢内部裂纹愈合的实验研究[J].金属学报,2000,36(6):622-625.(WEI Dong-bin,HAN Jing-tao,XIE Jian-xin,et al.Experimental study on inner crack healing in steel during hot plastic deforming[J].Acta Meta-llurgica Sinica,2000,36(6):622-625.(in Chinese))
[15] 唐鼎,张卿卿,方文利,等.基于空洞演化理论的挤压焊合描述模型[J].机械工程学报,2014,50(22):34-41.(TANG Ding,ZHANG Qing-qing,FANG Wen-li,et al.Modeling of the extrusion seam welding based on the void evolution[J].Journal of Mechanical Engineering,2014,50(22):34-41.(in Chinese))
[16] 刘文辉,刘龙飞,唐建国.FCC晶体中孔洞长大行为的研究[J].工程力学,2010,27(6):228-231,251.(LIU Wen-hui,LIU Long-fei,TANG Jian-guo.The study of void growth behavior in FCC crystal[J].Engineering Mechanics,2010,27(6):228-231,251.(in Chinese))
[17] 周航,孔纲强,曹兆虎,等.椭圆形孔扩张弹性分析[J].固体力学学报,2015,36(1):85-91.(ZHOU Hang,KONG Gang-qiang,CAO Zhao -hu,et al.Elastic analysis of elliptical cavity expansion[J].Chinese Journal of Solid Mechanics,2015,36(1):85-91.(in Chinese))
[18] 姜晶晶,林卓英,冯淼林,等.温度对Cr5 冷轧辊钢断裂韧度影响的试验研究[J].锻压技术,2012,37(4):135-139.(JIANG Jing-jing,LIN Zhuo -ying,FENG Miao -lin,et al.Experimental study on temperature influence to fracture toughness of Cr5 cold roll steel[J].Forging & Stamping Technology,2012,37(4):135-139.(in Chinese)