高速及重载道岔在线热处理钢轨压型跟端的感应热处理

Induction heating treatment of online heat treatment steel rail with forming heel-end for high-speed and heavy haul railway

为使高速及重载道岔AT钢尖轨跟端锻造热处理后组织与性能满足最新标准和线路使用要求,采用自主研发钢轨全断面感应加热+喷风冷却生产线,对高速及重载道岔60AT2-U71MnG及60AT1-U75V在线热处理钢轨压型跟端进行了热处理工艺试验,观察了硬化层的显微组织,检测了钢轨化学成分、硬化层深度、表面硬度、断面硬度、抗拉强度、伸长率及疲劳性能。结果表明,60AT2-60 kg/m(U71MnG材质)及60AT1-60 kg/m(U75V材质)在线热处理钢轨压型跟端经热处理后,钢轨轨头中心踏面硬化层深度不小于30 mm,显微组织为索氏体,表面硬度不小于320 HBW,抗拉强度不小于1200 MPa,伸长率不小于11%,表面硬度变化范围小于30 HBW,热影响软化区小于40 mm,弯曲疲劳强度达到200万次不断,各项技术指标均满足相关要求,可满足线路使用需求。

In order to make the structure and properties of forming heel-end of the steel rail for high-speed and heavy haul railway to meet the new standard and railway application requirements after heat treatment,the heat treatment experiment was carried out on 60 AT2-U71 MnG and 60 AT1-U75 V steel rail forming heel-end for high-speed and heavy haul railway after online heat treatment by using self-developed automatic production line of full section induction heating and cooling. The microstructure of hardened layer was observed by means of optical microscopy. The chemical composition,depth of hardened layer,the hardness of cross-section and surface,the tensile strength and elongation and fatigue property were measured for the rail. The results show that the 60 AT2-60 kg/m( U71 MnG) and 60 AT1-60 kg/m( U75 V) steel rail forming heel-end after heat treatment,the depth of hardened layer in rail head tread of it is more than 30 mm,the microstructure is sorbite. The hardness of surface is more than 320 HBW,the tensile strength is more than 1200 MPa,and the elongation is more than 11%. The change range of surface hardness is less than 30 HBW. After heat treatment,heat affected soften zone is less than40 mm. There is no fracture by bending fatigue test when cycled more than two million times. All data of the AT steel rails can meet the corresponding technical requirements,and the steel rail can meet the requirements for application.