关键词: 在线热处理AT钢轨, 压型跟端, 硬化层深度, 力学性能, 热影响区

Abstract: 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 60AT2-U71MnG and 60AT1-U75V 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 60AT2-60 kg/m(U71MnG) and 60AT1-60 kg/m(U75V) 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 than 40 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.

Key words: AT steel rail after on-line heat treatment, forming heel-end, depth of hardened layer, mechanical properties, heat affected zone