X80管线钢在酸性环境下的氢致开裂行为研究

Hydrogen Induced Cracking Behavior of X80 Pipeline Steel in Acidic Environment in China

目的研究X80管线钢在我国典型酸性环境(鹰潭土壤模拟溶液)下的氢致开裂行为。方法采用电化学动电位扫描技术、慢应变速率拉伸实验和扫描电镜技术,分析氢在X80管线钢中的渗透行为、材料的放氢行为、电化学充氢对材料拉伸性能的影响以及材料断口的形貌。结果通过氢渗透实验测得,在室温下,氢在X80管线钢中的的氢扩散通量J∞=7.31×10-11mol/(cm2·s),有效扩散系数Deff=5.36×10-8cm2/s,可扩散氢浓度C0=7.64×10-5mol/cm3。钢中的氧化铝类非金属夹杂及表面点蚀坑促进了氢致裂纹的萌生,充氢后试样发生穿晶断裂。随着充氢时间的增加,断口由韧性断裂转变为脆性断裂,氢致开裂敏感性增高。结论 X80管线钢在我国典型酸性环境下(鹰潭土壤模拟溶液)具有较高的氢致开裂敏感性。

Objective To investigate the hydrogen induced cracking （ HIC ） behavior of X80 pipeline steel in the typical acidic environment （simulated solutions of the acidic soil in Yingtan ）. Methods Using the potentiodynamic polarization curves, slow strain rate test （SSRT） and SEM technology, the behavior of hydrogen permeation, the behavior of hydrogen release, the influence of tensile properties after hydrogen charging and the fracture morphology were analyzed. Results According to the result of hydrogen permeation test, the hydrogen diffusion flux at room temperature was 7.31×10^-11 mol/（ cm^2·s）, the effective diffusivity of hydrogen was 5.36×10^-8 cm^2/s and the diffusible hydrogen concentration was 7.64×10^-5 mol/cm^3. Moreover, the alumina nonmetallic inclusions and surface pitting promoted the initiation hydrogen induced crack, and the failure mode was transgranular cracking after hydrogen charging. With the increase of hydrogen charging time, the fracture morphology changed from ductile fracture to brittle fracture, and the sensitivity to HIC increased. Conclusion X80 pipeline steel had high sensitivity to HIC in the typical acidic environment （ simulated solutions of the acidic soil in Yingtan）.