U71Mn和U75V钢轨钢疲劳短裂纹的扩展行为  

Propagation of Short Fatigue Crack in U71Mn and U75V Rail Steels

作　　者：李晶晶[1] 田常海[2] 汪越胜[1] 

机构地区：[1]北京交通大学工程力学研究所,北京100044 [2]铁道部科学研究院金属及化学研究所,北京100081

出　　处：《钢铁研究学报》2006年第4期37-40,共4页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(50271048)

摘　　要：在扫描电镜下对U71Mn和U75V钢轨钢的Ⅰ型低周疲劳加载和准静态加载下裂纹扩展的过程进行了观察。研究发现,从整体上看材料没有产生明显的宏观塑性变形,属准解理断裂。但从微观上看,裂纹的微观扩展路径曲折、不连续,常伴有分枝裂纹的形成。可观察到局部有韧窝、滑移线等典型的韧性断裂特征。尤其是U71Mn钢轨钢中还伴有局部的撕裂等更强烈的变形。钢轨钢U71Mn比U75V的抗疲劳裂纹扩展性能和韧性略优。The propagation of fatigue cracks in U71Mn and U75V rail steels under Ⅰ -mode low fatigue cycles and quasi static loads was observed by SEM. It was found that the fatigue fracture is mainly of quasi brittle fracture without obvious macroscopic plastic deformation, However, the zig-zag and discontinuous microscopic growth path of fatigue cracks with some branching cracks expanded locally was observed. For quasi static loads, phenomenon of dimples and glide lines, which are typical characteristics of ductile fracture was shown in local area. Especially, strong deformation such as local tearing was observed in U71Mn rail steel. It can be concluded that the resistance to fatigue crack growth and the ductility of U71Mn rail steel is a little better than U75V rail steel,

关 键 词：U71Mn U75V 疲劳断裂 扫描电镜 

分 类 号：TG115[金属学及工艺—物理冶金]