【摘要】 利用电子背散射衍射(EBSD)实验分析了马氏体组织的微区弹性刚度分布,并在此基础上建立应力-氢交互作用的耦合有限元模型,研究马氏体组织的各向异性对微区应力和氢分布的影响。结果表明:相邻Block板条束之间的取向差互成60°,在同一受力方向上不同Block板条束具有不同的弹性刚度,从而引发组织间的微区应力和氢呈不均匀分布,Block板条束是表征微区应力的组织单元。Block板条束弹性刚度梯度和组织尺寸决定了组织间的应力集中,而应力集中又影响了氢的分布。弹性刚度梯度高和板条束尺寸大的Block组织单元应力集中较为严重,并富集高浓度的氢,最终引发氢致开裂。上述模拟结果与氢脆断口的微观断裂形貌和氢脆裂纹的EBSD分析结果相符。更多还原

【Abstract】 Elastic stiffness distribution of martensite microstructure was analyzed by using Electron Back Scatter Diffraction(EBSD)experiment,based on which the coupled finite element model of stress-hydrogen interaction was established to study the influence of martensitic microstructure anisotropy on the micro local stress and hydrogen distribution.The results show that misorientation between adjacent Block Laths is 60°,and different Block Laths have different elastic stiffness in the same loading direction,which resulted in the heterogeneous distribution of micro stress and hydrogen,and micro stress can be characterized by microstructure element of Block Lath.Elastic stiffness gradient and Block size play a significant role in stress concentration among microstructures,and while stress concentration can affect hydrogen distribution.High elastic stiffness gradient and large size of Block Lath cause high stress concentration,accumulate high concentration of hydrogen,which initiate crack of hydrogen embrittlement in the end.The above results are consistent with micro fracture morphology and EBSD experiment on crack region.更多还原