利用光学显微镜、扫描电镜及透射电镜等仪器对SA516Gr70热轧容器钢板的显微组织结构进行了分析, 并采用氢渗透试验和无损探伤方法研究了其氢渗透特征及开裂行为。结果表明: SA516Gr70容器钢板的显微组织为呈带状分布的铁素体和珠光体, 亚结构中含有大量的位错及少量的第二相, 并含有大尺寸的复合夹杂物;SA516Gr70容器钢板中的可扩散氢含量随着氢渗透时间的延长而增加, 极限氢含量(质量分数,下同)约为0.000 784%;在10 mA·cm-2氢渗透电流密度作用下, 可扩散氢含量在0.000 409%以下时SA516Gr70容器钢板不会发生氢致开裂, 当可扩散氢含量达到0.000 549%以上时便会发生氢致开裂。

The microstructure of SA516Gr70 hot-rolled press vessel steel plate was investigated by optical microscope, scanning electron microscope and transmission electron microscope, and the hydrogen permeation characteristics and hydrogen induced cracking behavior were studied by hydrogen permeation experiment and nondestructive test. The results show that the microstructure of SA516Gr70 press vessel steel plate was banded ferrite and pearlite, and there were a large number of dislocation, a small amount of second phase and some large size composite inclusions. The diffusion hydrogen content in SA516Gr70 press vessel steel plate increased with the increase of hydrogen permeation time, and the limit diffusion hydrogen content was about 0.000 784%. Under the condition of 10 mA·cm-2 electric current density, hydrogen induced cracking would not happen when the diffusion hydrogen content was lower than 0.000 409%. However, when the diffusion hydrogen content was above 0.000 549%, hydrogen induced cracking would happen.