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用抛光的恒位移试样对处理到不同强度(σ_b=92～185公斤/毫米~2)的4种低合金钢在各种致氢环境(如电解充氢、纯氢、气体H_2S、水介质、H_2S水溶液、缓蚀剂水溶液、丙酮、酒精等有机溶液)下跟踪观察了氢致裂纹的产生和扩展过程。与此同时也测量了各种致氢环境(电解充氢、H_2S水溶液、水溶液、水中阴极化和阴极极化)下的K_(ISCC)(或K_(IH))和da/dt。并研究了它们随强度变化的规律。 结果表明,当加载裂纹前端的K_I>K_(ISCC)(K_(IH))后,在上面所说的任何一种致氢环境下都能产生氢致滞后塑性变形,并由此导致裂纹的产生和扩展。即随着氢的扩散进入,原裂纹前端塑性区及其变形量逐渐增大。对超高强钢,在滞后塑性区端点形成不连续的氢致裂纹,它们随滞后塑性变形的发展逐渐长大以致互相连接。当强度降低时,氢致裂纹沿滞后塑性区边界连续地向前扩展。这就表明,在Ⅰ型裂纹条件下,“氢脆”是氢致滞后塑性变形的必然结果。 在所有致氢环境下,止裂K_(ISCC)(K_(IH))均随钢的强度下降而升高。强度相同时,水中加缓蚀剂和阳极极化使K_(ISCC)升高,阴极极化使K_(ISCC)下降,,da/dt升高,而在H_2S饱和溶液以及加载电解充氢时K_(ISCC)(K_(IH))最低,da/dt最高。 实验也表明,在电解充氢条件下还能以另一种机构形成裂纹。它们的产生和
Four kinds of low alloyed steels treated with different intensity (σ_b = 92 ~ 185 kg / mm ~ 2) were treated with polishing constant displacement specimen in a variety of hydrogen-producing environments such as electrolytic hydrogenation, pure hydrogen, gaseous H 2 S, aqueous media , H 2 S aqueous solution, aqueous solution of corrosion inhibitor, acetone, alcohol and other organic solvents) to observe the hydrogen induced crack growth and expansion process. At the same time, K_ (ISCC) (or K_ (IH)) and da / dt were measured under various hydrogen-producing environments (Electrolysis, H 2 S solution, aqueous solution, water cathodic and cathodic polarization). And studied the law of their changes with the intensity. The results show that hydrogen-induced hysteresis plastic deformation can be produced in any of the hydrogen-generating environments mentioned above after K_I> K_ (ISCC) (K_ (IH)) at the tip of the crack is loaded, And expansion. That is to say, as the diffusion of hydrogen enters, the plastic zone at the front of the original crack and its deformation gradually increase. For super-high strength steels, discontinuous hydrogen-induced cracks are formed at the end of the hysteretic plastic zone. They gradually grow up with the development of delayed plastic deformation so as to be connected to each other. As the strength decreases, the hydrogen-induced crack propagates continuously along the boundary of the hysteretic plastic zone. This shows that in the type Ⅰ crack condition, “hydrogen embrittlement” is the inevitable result of hydrogen induced lag plastic deformation. In all hydrogen-releasing environments, the crack arrest K_ (ISCC) (K_ (IH)) increases with the decrease of the strength of the steel. At the same intensity, K_ (ISCC) increased with inhibitor and anodic polarization in water, K_ (ISCC) decreased and da / dt decreased with cathodic polarization, whereas in H_2S saturated solution and K_ (ISCC) (K_ (IH)) lowest, da / dt highest. Experiments also show that cracks can be formed by another mechanism under the condition of electrolysis and hydrogen charging. Their production and