45号钢氢致脆断试验与GTN模型数值模拟研究

采用电化学方法对试样充氢后再进行单轴拉伸,在此基础上研究45号钢的氢致脆断问题.试验观察到,随充氢时间增加,试样的延伸率和平均断裂应变减小,断口韧窝数目减少,准解理区域增加.但该改变逐渐减缓,充氢大于72 h若继续充氢试样延性和断裂应变几乎不再变化.基于试验观测,将HEDE机制和受氢影响的材料微孔洞演化机制引入GTN本...

Experimental and GTN Model-based Numerical Study on Hydrogen-induced Brittle Fracture of 45 Steel

The hydrogen induced brittle fracture of 45 steel was studied by uniaxial tension after hydrogen charging with electrochemical method. It is observed that with the increase of hydrogen content, the elongation and average fracture strain decrease, the number of dimples decreases and the quasi-cleavage area increases. However, the change with hydrogen charging time is gradually slowed down, and the ductility and fracture strain of the sample do not change after 144 h of hydrogen charging. According to the experimental observation, the HEDE mechanism and the evolution mechanism of material microvoids affected by hydrogen are introduced into the GTN constitutive model, and the phenomenon that the volume fraction of microvoids nucleation increases with the increase of hydrogen concentration, and the initiation of nucleation and polymerization will be advanced is considered. The results show that with the increase of hydrogen concentration, the elongation and contraction at rupture decrease, and the position of the crack initiation point changes with the change of hydrogen concentration distribution. These results can reasonably explain and reproduce the process and phenomena observed in the experiment.