U75V钢轨锯切断裂原因分析  

Analysis of Reasons for Sawing Fracture of U75V Rail

作　　者：王瑞敏 周剑华 朱敏 刘丰收[2] 李闯[2] 费俊杰 郑建国 徐志东 WANG Ruimin;ZHOU JianhuaI;ZHU Min;LIU Fengshou;LI Chuang;FEI Junjie;ZHENG Jianguo;XU Zhidong(Wuhan Branch of Baosteel Central Research Institute（R and D Center of Wuhan Iron ＆ Steel Co.,Ltd.）,Wuhan Hubei 430080,China;Metals and Chemistry Research Institute,China Academy of Railway Sciences,Beijing 100081,China)

机构地区：[1]宝钢股份中央研究院武汉分院(武钢有限技术中心),湖北武汉430080 [2]中国铁道科学研究院金属及化学研究所,北京100081

出　　处：《中国铁道科学》2018年第4期50-55,共6页China Railway Science

基　　金：武汉市科技计划项目(2013011403010505)

摘　　要：针对从U75V钢轨顶面垂直锯轨至接近轨底处时,轨腰下部及轨底出现垂直断裂的现象,通过对锯切断裂钢轨断口进行宏观观察、微观扫描和金相组织检验,并采用有限元仿真方法对钢轨锯切过程中和采取不同支垫方式的受力进行分析,研究钢轨锯切断裂产生的原因并提出预防措施。结果表明:裂纹起源于钢轨轨腰三角区、夹角为45°锯切休止痕的中间位置;因支垫方式不当,锯切到断口位置时,由重力作用引起的锯口局部区域应力值大于钢轨的拉伸强度,锯口表面裂纹尖端应力强度因子(57~140 MPa·m^(1/2))远大于钢轨母材的断裂韧性(36.6 MPa·m^(1/2)),导致钢轨瞬时开裂;通过在钢轨重心位置处进行支垫的方式可消除重力引起的钢轨变形,有效避免锯切时的断裂现象。Aiming at the phenomenon of the vertical fracture at the lower part of web and the base of U75 V rail when being vertically sawed from the top surface to near the base,the fracture surface of the rail was tested by macroscopic observations,microscopic scanning and metallographic inspection.The forces during the process of sawing and under different supporting methods were analyzed by finite element simulation method.The causes for rail sawing fracture were studied and the preventive measures were proposed.Results show that the cracks originate from the middle position between the triangular zone of rail web and the sawing repose marks with the angle of 45°.When sawing to the fracture surface position,the stress in the local area of sawing kerf caused by the action of gravity is greater than the tensile strength of rail due to the improper supporting pad.The stress intensity factor（57-140 MPa·m^1/2）at the crack tip of sawing kerf surface is far greater than the fracture toughness（36.6 MPa·m^1/2）of rail base metal,leading to the instantaneous cracking of rail.The fracture during the process of sawing can be effectively avoided by using the supporting pad at the center position of gravity of rail to eliminate the rail deformation caused by gravity.

关 键 词：U75V钢轨 锯切 断裂 支垫方式 

分 类 号：U213.42[交通运输工程—道路与铁道工程] TG142.1[一般工业技术—材料科学与工程]