The Study Of Heat Treatment Process And Organizational Performance On High-carbon Micro Alloy Pearlite Rail Steel

As we know,improving the comprehensive performance of rail steel to meet the needs of the development of heavy-duty railways is an urgent issue in the field of rail steel research.Composition design and heat treatment process are important ways to improve the comprehensive performance of hypereutectoid pearlitic rail steel.Through composition design and heat treatment process,the lamellar spacing of hypereutectoid pearlitic rail steel can be reduced to obtain higher tensile strength and fatigue cracks.The number of extended cycles.In this paper,two groups of experimental steels smelted by a certain steel mill are the research objects,and the effects of carbon content,microalloying elements and heat treatment process on the mechanical properties and fatigue crack growth properties of the two groups of experimental steels are analyzed.BGRE rail comparison.In this paper,the1# experimental steel with a carbon content of 0.8?0.9wt% and the 2# experimental steel with a carbon content of 0.9?1.0wt% are heat treated,and the experimental steel is cooled to 560?,580? and 600 at a cooling rate of 8?/s.? and isothermal for 20 s,30s and60 s to test the mechanical properties,microstructure and fatigue properties of the experimental steel after heat treatment.The overall performance of the 1# experimental steel 1-3# after the isothermal temperature of 580? for 30 s is the best.At this time,the tensile strength is 1417.8MPa,the Brinell hardness is 454 HB,the pearlite interlayer spacing is 64.33 nm,and the number of fatigue cycles is 141.7.Ten thousand times;the comprehensive performance of the 2-2# experimental steel is the best after the 2#experimental steel is isothermal at 580? for 30 s.At this time,the tensile strength is1383.3MPa,the Brinell hardness is 371 HB,the pearlite interlayer spacing is 96.5nm,and the fatigue The number of cycles is 715,000 times.The mechanical properties and fatigue properties of 1-3# experimental steel and2-2# experimental steel are compared with heat-treated BGRE rails produced by a steel plant.1# experimental steel increases the content of Cr element,so that 1# experimental steel can precipitate more dispersively distributed ferrochrome carbides before the eutectoid reaction,which produces precipitation strengthening effect in 1# experimental steel;a small amount of Cr element is added to make The hypereutectoid steel containing Mn reduces the tendency of grain growth and refines the structure of the hypereutectoid steel.And through the heat treatment process at 580? isothermal 30 s,the 1-3#experimental steel has obtained a finer pearlite lamella structure,and the dispersed chromium iron carbide in the matrix is shared with the cementite lamella in the pearlite lamella.It acts to hinder the movement of dislocations and improve the overall performance of 1# experimental steel.The 2# experimental steel increases the carbon content to 0.9 ?1.0%.The increase in the C element content of the 2# experimental steel makes the 2-2# experimental steel at a 580? isothermal 30 s higher in tensile strength and Brinell hardness than the heat-treated BGRE steel.However,the number of fatigue crack growth cycles is lower than that of heat-treated BGRE steel.Through the above experimental research,the effects of microalloying elements and heat treatment process on the mechanical properties and fatigue crack growth properties of the two sets of experimental steels are analyzed.Through the optimization of composition and heat treatment process,the performance of 1-3# experimental steel is greatly improved compared with heat-treated BGRE;the performance of 2-2#experimental steel is slightly improved than that of heat-treated BG400.