摘要
针对高强钢在硫化氢环境中腐蚀疲劳数据极为缺乏的现状,研究高压气瓶材料4130X在硫化氢腐蚀介质中的疲劳裂纹扩展速率。结合气瓶实际运行的环境和应力状态,应用改进型WOL(wedge-opening-loading)试样,在自行改造的专用低周腐蚀疲劳试验机上,完成0.0067Hz超低频率下饱和H2S溶液、中等浓度H2S溶液和空气三种环境下的腐蚀疲劳试验,并用Paris公式进行两段式拟合,得出da/dN—ΔK的数学表达式。将试样微观断口的变化与宏观应力强度因子K的变化进行对比研究,给出不同环境中三个阶段K值的定量结果。结果表明:相同条件下,H2S环境中的疲劳裂纹扩展速率比空气环境中大20倍以上;但当H2S浓度达到一定范围后,对da/dN影响并不按比例增长,浓度相差11倍时,da/dN相差2.4倍,H2S腐蚀介质的存在加速了疲劳破坏。
Due to the status quo of lack of data about hlgh-tensile steel in H2S environment, the fatigue crack growth rate of 4130X steel used in compressed H2S vessel was investigated. Considering its practical operating ambient and stress condition, after overcoming enormous difficulties, the seff-modified WOL（wedge-opening-loading） specimens were used in the specifically designed low-cycle corrosion fatigue testing machine, in order to complete the tests under 0.006 7 Hz, in saturated H2S, moderate concentration and air environment, respectively. Moreover, the mathematical expression of da/dN-△K was concluded by the fitted curve using Paris formula. Contrast study between the changes of the specimens＇ microscopic fracture and the stress intensity factor K was conducted. Therefore, the quantitive result of K of three stages in different environment was determined. The results show that： 1） da/dN in H2S environment is above 20 times of that in air environment. 2） when the concentration of H2 S reaches to a certain range, its effect on da/dN is not scaled up. da/dN differs by 2.4 times while the concentration differs by 11 times. The corrosion medium accelerates the fatigue failure.
出处
《机械强度》
CAS
CSCD
北大核心
2009年第6期972-978,共7页
Journal of Mechanical Strength
