摘要
利用U75V和U78CrVH两种不同强度级别的珠光体钢进行了显微组织、氢吸附特征、氢扩散系数及氢脆敏感性的试验研究,分析了强度对珠光体钢氢脆敏感性的影响并初步讨论了珠光体钢轨钢的氢脆断裂机理。结果表明:与U75V相比,U78CrVH具有更高的强度和韧性,这与其珠光体组织片层间距相对较小和渗碳体片层厚度较薄密切相关。U78CrVH的氢脆敏感性指数(IHE)上升幅度随氢含量增加明显增大,当氢质量分数达到2.3×10^(-6)时,U75V的IHE超过了50%,U78CrVH的IHE超过了70%,此时材料的塑性损失较为明显,材料发生了明显的氢脆现象。在断口中未发现沿晶裂纹,以解理特征为主。与U75V相比,U78CrVH钢的断口特征变化在充氢前后更加明显,这表明强度提升后的珠光体钢的氢脆敏感性也显著增加。这是由于U78CrVH钢中含有更高的碳成分、更多的渗碳体-铁素体界面及位错,与内部局部较高的应力场交互作用形成氢的高度偏集所致。
U75V and U78CrVH pearlitic rails with different strength were used to carry out experimental researches on the microstructure,hydrogen adsorption characteristics,hydrogen diffusion coefficient and hydrogen embrittlement susceptibility.Meanwhile,the influence of strength on the hydrogen embrittlement susceptibility of pearlitic steels was analyzed and the hydrogen embrittlement fracture mechanism was discussed.The results show that U78CrVH has higher strength and toughness than U75V,which is closely related to small interlamellar spacing of pearlite layers and thinner cementite lamb thickness.The increase range of hydrogen embrittlement susceptibility index of U78CrVH increases significantly with the increase of hydrogen content.When the hydrogen content exceeds 2.3×10^(−6),the reduction of area of U75V exceeds 50%,and the reduction of area of U78CrVH exceeds 70%.At this point,the plasticity loss of the material is more obvious,and the material has hydrogen embrittlement.The fracture morphology of the sample is mainly cleavage,which is no intergranular fracture.The change in fracture characteristics of U78CrVH steel is more pronounced before and after hydrogen charging compared to U75V.It indicates that the hydrogen embrittlement susceptibility of pearlite steel with increased strength also significantly increases.The reason is that U78CrVH steel contains higher carbon content,more cementite-ferrite interfaces and dislocations,which interact with the higher local stress field inside to form a high concentration of hydrogen.
作者
张倩
刘佳朋
杨其全
吴广
张程翔
ZHANG Qian;LIU Jiapeng;YANG Qiquan;WU Guang;ZHANG Chengxiang(Metals and Chemistry Institute,China Academy of Railway Sciences Corporation Limited,Beijing 100081,China;School of Mechanical Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China;Zhengzhou Railway Equipment Manufacture Co.,Ltd.,Zhengzhou Henan 450004,China)
出处
《高速铁路新材料》
2023年第6期15-22,共8页
Advanced Materials of High Speed Railway
基金
中国铁道科学研究院集团有限公司基金(2020YJ084)。
关键词
珠光体钢轨
强度
片层间距
氢脆敏感性
pearlitic rail
strength
interlamellar spacing
hydrogen embrittlement susceptibility
