基于内聚力模型的AISI4135高强钢氢致滞后断裂数值模拟

来源期刊：金属学报2011年第5期

论文作者：王艳飞 巩建鸣 蒋文春 姜勇 唐建群

文章页码：594 - 600

关键词：内聚力模型； 氢致滞后断裂； 高强钢； 氢脆

Key words：cohesive zone modeling(CZM)； hydrogen induced delayed fracture(HIDF)； high strength steel； hydrogen embrittlement

摘    要：基于有限元ABAQUS软件,利用内聚力模型和与H相关的线性内聚力—张开位移率关系,开发了顺次耦合的氢致滞后断裂有限元计算程序,预测了预充H的AISI4135高强钢圆柱缺口试样在常载荷拉伸条件下的滞后断裂时间和裂纹萌生位置,同时考察初始H含量、缺口尖端应力集中系数和拉伸载荷对滞后断裂的影响,并和文献报道的相关实验结果进行比较.结果表明,CZM模型能够较好地模拟预充H高强度钢的氢致滞后断裂过程,预测结果和实验结果基本一致.氢致滞后断裂存在H临界值,当缺口尖端高应力区聚集的H浓度达到临界值时,裂纹才会在此萌生,此临界值与材料所受的载荷大小、缺口尖端的应力集中系数(缺口半径)有关,而与初始H浓度无关随着缺口尖端应力集中系数、拉伸载荷的降低,滞后时间将显著增大,临界H浓度也增大.

Abstract: High strength steels are susceptible to hydrogen induced delayed fracture (HIDF). A sequential coupling calculation on HIDF of high strength steel was developed based on cohesive zone modeling (CZM) using finite element program-ABAQUS.The calculation procedure contained three steps:elastic plastic stress analysis,stress assisted transient hydrogen diffusion and cohesive stress analysis using hydrogen dependent linear traction-separation law.Using this method,the prediction of fracture time and crack initiation location of pre-charged notched bar of AISI4135 high strength steel was obtained.The effects of stress concentration factor, initial hydrogen content,and tension load were also considered.The results show:(ⅰ) predictions of the time to fracture were in good quantitative agreement with the experimental results; the hydrogen dependent cohesive zone modeling can be used in prediction of failure in actual structures;(ⅱ) crack initiation occurs when a critical hydrogen concentration at the location of stress peak is reached by accumulation,the critical hydrogen concentration is dependent on stress concentration factor and tension load,but independent of initial hydrogen content;(ⅲ) as one of the three parameters mentioned above decreasing,the fracture initiation time and the critical hydrogen concentration increase.