大型锻件中氢扩散的研究
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摘要
主要从两个方面进行了氢扩散的研究。首先应用电化学渗氢的方法进行了氢扩散系数的测定,实验的对象可以是任何金属,且测定结果可以直接运用在氢扩散的定量计算中,为检测锻件中氢的积累及扩散提供基本参数及计算依据。其次利用有限元分析方法,建立了简化后的八分之一有限元模型,并设定氢浓度场扩散结果的提取路径,得到了沿扩散路径的氢浓度分布情况。根据氢扩散浓度场的有限元分析可知,对于初始氢浓度相同的锻件,低温时的氢扩散有利于锻件边部氢浓度的降低,高温时的氢扩散有利于锻件内部氢分布的均匀化。通过对等温扩氢热处理过程氢浓度的有限元分析可知,当锻件的初始氢浓度较低时,需采取低温等温扩氢方法;锻件的温度越高锻件的边部氢浓度则越高;在中间断面氢含量差距不大、锻件平均氢浓度不高的情况下,以心部氢浓度为确定等温扩氢温度的第一依据,以锻件中的氢含量为确定等温扩氢温度的第二依据。
The hydrogen diffusion behavior from two aspects was studied. Firstly,the hydrogen diffusion coefficient was determined by the method of electrochemical hydrogen permeation. The object of the experiment can be any metal,and the results can be directly used in the quantitative calculation of hydrogen diffusion,which can provide the basic parameters and calculation basis for the accumulation and diffusion of hydrogen in the forgings. Secondly,by using finite element analysis method,a simplified one-eighth hydrogen diffusion finite element model was established,the extraction path of hydrogen concentration field diffusion results was set up,and the situation of hydrogen concentration distribution along the diffusion path was obtained. According to the finite element analysis of hydrogen concentration field,hydrogen diffusion is conductive to hydrogen concentration reduction of forging edge under lower temperature and to homogenization of hydrogen distribution inside the forgings under higher temperature for forgings with equal initial hydrogen concentration. Through finite element analysis about the hydrogen concentration during diffusion hydrogen heat treatment under isothermal conditions,diffusion hydrogen heat treatment under isothermal condition of lower temperature should be adopted for forgings with lower initial hydrogen concentration,and the hydrogen concentration of forging edge increases with the increase of forging temperature. Under the conditions that the hydrogen content difference of middle section and the average hydrogen concentration are smaller,the hydrogen concentration at the center is the first basis to determine the isothermal hydrogen diffusion temperature,and the hydrogen content in the forgings is the second basis.
The hydrogen diffusion behavior from two aspects was studied. Firstly,the hydrogen diffusion coefficient was determined by the method of electrochemical hydrogen permeation. The object of the experiment can be any metal,and the results can be directly used in the quantitative calculation of hydrogen diffusion,which can provide the basic parameters and calculation basis for the accumulation and diffusion of hydrogen in the forgings. Secondly,by using finite element analysis method,a simplified one-eighth hydrogen diffusion finite element model was established,the extraction path of hydrogen concentration field diffusion results was set up,and the situation of hydrogen concentration distribution along the diffusion path was obtained. According to the finite element analysis of hydrogen concentration field,hydrogen diffusion is conductive to hydrogen concentration reduction of forging edge under lower temperature and to homogenization of hydrogen distribution inside the forgings under higher temperature for forgings with equal initial hydrogen concentration. Through finite element analysis about the hydrogen concentration during diffusion hydrogen heat treatment under isothermal conditions,diffusion hydrogen heat treatment under isothermal condition of lower temperature should be adopted for forgings with lower initial hydrogen concentration,and the hydrogen concentration of forging edge increases with the increase of forging temperature. Under the conditions that the hydrogen content difference of middle section and the average hydrogen concentration are smaller,the hydrogen concentration at the center is the first basis to determine the isothermal hydrogen diffusion temperature,and the hydrogen content in the forgings is the second basis.
引文
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[8]李勇峰,蔡丽安,阚文彬,等.氢在低碳钢中的渗透扩散特性[J].华东理工大学学报(自然科学版),2013,39(2):222-227.LI Yongfeng,CAI Lian,KAN Wenbin,et al.Diffusion characteristics of hydrogen in low carbon steel[J].Journal of East China University of Science and Technology(Natural science edition),2013,39(2):222-227.
[2]吕炎.锻件缺陷分析与对策[M].北京:机械工业出版社,1999.LV Yan.Forging defects analysis and countermeasures[M].Beijing:China Machine Press,1999.
[3]刘相华.刚塑性有限元及其在轧制中的应用[M].北京:冶金工业出版社,1994.LIU Xianghua.Rigid plastic finite element method and its application in rolling[M].Beijing:Metallurgical Industry Press,1994.
[4]杨慧,王玉峰,李文学,等.42Cr Mo钢大锻件去氢退火节能新工艺的研究[J].兵器材料科学与工程,2002,25(6):41-42.YANG Hui,WANG Yufeng,LI Wenxue,et al.Research on new energy saving technology of 42Cr Mo steel forgings for hydrogen removal[J].Weapon Materials Science and Engineering,2002,25(6):41-42.
[5]ALEFELD G,VLKL J.Hydrogen in Metals[M].Berlin:Springer,1978.
[6]赵亮,余刚,张学元,等.氢在钢中低温扩散系数[J].腐蚀科学与防护技,2005,17(5):349-351.ZHAO Liang,YU Gang,ZHANG Xueyuan,et al.Hydrogen diffusion coefficient at low temperature in the steel[J].Corrosion Science and Protection Technology,2005,17(5):349-351.
[7]刘菲,苏运星,王仲民,等.菲克定律在氢扩散系数研究中的应用[J].广西大学学报,2010,35(5):841-846.LIU Fei,SU Yunxing,WANG Zhongmin,et al.Application of Fick's law in measurement of hydrogen diffusion coefficient by electro chemical method[J].Journal of Guangxi University,2010,35(5):841-846.
[8]李勇峰,蔡丽安,阚文彬,等.氢在低碳钢中的渗透扩散特性[J].华东理工大学学报(自然科学版),2013,39(2):222-227.LI Yongfeng,CAI Lian,KAN Wenbin,et al.Diffusion characteristics of hydrogen in low carbon steel[J].Journal of East China University of Science and Technology(Natural science edition),2013,39(2):222-227.