连续充氢条件下30CrMnSiA钢的(Ⅰ+Ⅱ)复合型氢致开裂

HYDROGEN ASSISTED CRACKING OF 30CrMnSiA STEEL UNDER CONTINUOUSLY HYDROGEN CHARGING AND (Ⅰ+Ⅱ) MIXED MODE LOADING CONDITION

随着高强钢的广泛应用及使用环境的复杂化,材料在工作环境中的氢脆问题日趋突出,与此有关的工程断裂事故屡见不鲜。工作于氢环境中的构件大多处于连续充氢条件下,并且由于实际构件内部缺陷形式多样、载荷复杂、裂纹方向各异,缺陷常常在复合型受载条件下扩展。但是,自从60年代将断裂力学引入氢致开裂研究以来,迄今主要研究了Ⅰ型受载条件下的开裂问题。对复合型应力腐蚀和氢致开裂只是研究了Ⅲ型及(Ⅰ+Ⅱ)复合型开裂。

Hydrogen assisted cracking (HAC) of 0. 3%C, 1%Cr, 1%Mn, 1%Si steel under continuously hydrogen charging and (Ⅰ+Ⅱ) mixed mode loading conditions was studied. Experimental results showed that under mixed mode loading conditions from mode I through mode Ⅱ ,the critical stress intensity factor K_H for HAC increased firstly and then decreased,thus at some K_Ⅱ/K_Ⅰ ratio K_(Hmax) occurred. In both mode Ⅰ and mode Ⅱ cases, however,K_(ⅠH) and K_(ⅡH) were rather low,and sometimes K_(ⅡH) was even lower than K_(ⅠH).