摘要
针对重载铁路直线段PG4钢轨从轨底起裂横向转纵向扩展断裂的问题,通过对断口进行宏观、微观形貌观察及金相组织分析、力学性能测试,分析钢轨裂纹产生及转向的原因。结果表明:PG4钢轨的伤损为轨底下表面锈蚀坑引起的钢轨横向疲劳裂纹,锈蚀是伤损钢轨轨底萌生横向疲劳裂纹进而快速向轨底两侧和轨头方向扩展的主要原因;裂纹扩展至轨头下颚部位时,由于轨头强度的增加、断面几何尺寸的增大、轨头下颚处沿钢轨纵向的断裂韧性未与轨头横向断裂韧性同比例提高,使得横向裂纹转向沿钢轨纵向扩展。
Aiming at the problem that PG4 rail in the straight section of heavy haul railway starts to crack from the rail bottom and propagates lateral spreading fracture to longitudinal fracture,the causes of rail crack and steering were analyzed by macro and micro morphology observation,metallographic structure analysis and mechanical property test.The results show that the damage of PG4 rail is transverse fatigue crack caused by corrosion pit on the surface under the rail. Corrosion is the main reason for the transverse fatigue crack at the rail bottom of the damaged rail and then rapidly expanding to both sides of the rail bottom and the rail head. When the crack propagates to the lower jaw of the rail head,due to the increase of the strength of the rail head,the geometric size of the section increases and the failure toughness along the longitudinal direction of the rail at the jaw of the rail head is not increased in the same proportion as the transverse failure toughness of the rail head,which make the transverse crack turn to extend along the longitudinal direction of the rail.
作者
吕晶
杨其全
许鑫
张倩
曹欣旺
冯博宇
LYU Jing;YANG Qiquan;XU Xin;ZHANG Qian;CAO Xinwang;FENG Boyu(Metals and Chemistry Research Institute,China Academy of Railway Sciences Corporation Limited,Beijing 100081,China)
出处
《铁道建筑》
北大核心
2021年第11期124-127,共4页
Railway Engineering
基金
中国铁道科学研究院集团有限公司金属及化学研究所基金(2019JH0102)。
关键词
重载铁路
钢轨断裂
试验研究
PG4钢轨
轨底锈蚀坑
断裂韧性
裂纹转向
heavy haul railway
rail fracture
experimental research
PG4 rail
rail base corrosion pit
fracture toughness
crack direction changing
