To develop high-strength,high-toughness and high-hardness wear-resistant rails for heavy-haul railways,the composition design and intermediate pilot test of U77MnCrH rail steel were conducted according to the C-Si-Mn-Cr compositional design system.Based on the microstructure and properties of the intermediate pilot test,steel with better microstructure and properties was selected for 75 kg·m-1 U77MnCrH rail rolling test.The microstructure and properties of 75 kg·m-1 U77MnCrH rail samples were studied using optical microscope,field emission scanning electron microscope,transmission electron microscope,a universal tensile testing machine and a hardness tester.The results show that as the content of chromium increases from 0.26％to 0.38％,the lamellar spacing of pearlite decreases from 165 nm to 146 nm,accompanied by an increase in tensile strength and hardness,but a decrease in yield strength Rp0.2 and elongation at fracture.As the content of silicon increases from 0.25％to 0.45％,the lamellar spacing of pearlite decreases from 165 nm to 132 nm,resulting in increased elongation at fracture and hardness,as well as a notable increase in yield strength Rp0.2,while the tensile strength remains relatively unchanged.The pearlite of rail steel with 0.45％silicon and 0.26％manganese is more uniform and finer with a more homogeneously distribution of lamellar spacing,achieving an optimal balance between mechanical properties and hardness.It demonstrates a tensile strength of 1,258 MPa,a yield strength Rp0.2 of 845 MPa,an elongation at fracture of 13.0％,hardness of rail head top surface of 384 HBW,and a cross-sectional hardness ranging from 36.2 to 38.8 HRC.The various indicators of the 75 kg·m-1 U77MnCrH rail provide valuable references for production practice.
关键词
重载铁路/75kg·m-1U77MnCrH钢轨/透射电子显微镜/万能拉伸试验机/珠光体
Key words
Heavy-haul railway/75 kg·m-1U77MnCrH rail/Transmission electron microscope/Universal tensile testing machine/Pearlite
万方数据