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310稳定型奥氏体不锈钢在严重电解充氢后能产生氢致滞后断裂.当氢含量较高K_I较低时,断口形貌由原来的韧窝变为准解理.奥氏体不锈钢缺口试样在充氢时,缺口前端的塑性区及其变形量能随着充氢时间增长而不断增大,即氢促进了位错的增殖和运动,当这种氢致局部塑性变形发展到临界值时便引起氢致裂纹的形核.这表明,氢致脆性裂纹是以位错的增殖和运动为先决条件的,但细节并不清楚.本文将通过充氢薄膜试样在透射电镜(TEM)中进行原位拉伸,研究氢致裂纹形核和位错发射及运动之间的关系;并和不含氢试样的类似研究进行对比,以揭示两者间的本质区别.
310 stable austenitic stainless steel can produce hydrogen induced hysteresis fracture after severe electrolysis and hydrogen charging.When the hydrogen content is high, K_I is low, the fracture morphology changes from the original dimple to the quasi-cleavage.The austenitic stainless steel notch test In hydrogen charging, the plastic zone at the front of the notch and its deformation can increase with the increase of hydrogen charging time, that is, hydrogen promotes the proliferation and movement of dislocations. When this hydrogen-induced local plastic deformation reaches the critical value Hydrogen-induced brittle cracks are presupposed by the propagation and movement of dislocations, but the details are not clear. In this paper, through the TEM (transmission electron microscopy) In-situ tensile study of hydrogen-induced crack nucleation and dislocation emission and the relationship between motion and comparison with similar studies without hydrogen samples to reveal the essential difference between the two.