Research On Enhancing Strength And Toughness Of Grade E Steel Coupler

With the continuous increasing of wagon load and running speed, all parts of freight cars have been received more loading weight. The coupler is the key part for linking locomotive and rolling stock, but coupler body has been detected failure phenomenon such as crack with the abominable running condition, which has been serious incipient fault of railway transport. Heavy load and increasing speed is the trend in our country's wagon development, so it is significant to develop high comprehensive properties reserved material for coupler.Failure analysis has been done in current couplers with cracks in coupler yoke key; aimed at high comprehensive properties reserved material, The chemical constitution has been adjusted and smelting method has been improved for the new steel, it's heat-treatment processing parameters has also been optimized, it's repeated tension and compression behavior, low-temperature impact behavior and frictional behavior are also has been tested.The results showed that the surface cracks of coupler yoke start from some spots of (?)ction arc surface, and expanding forwards along radial direction in a brittle fracture way. When arrivd the intermediate zone between basal body and hardening zone, the crack turned to axial and circumferential direction and expanding in fatigue way. After chemical constitution adjusting and smelting method improvement, the mechanical property of new ZG29MnMoNi-E grade steel meets the standard of TB/T2942-1999 and AAR. M 211 , and surpasses the average level of current material for coupler used in two most famous railway factory. The fatigue strength of new steel is 342MPa, better than current steel by 9.26%; after wearing for 1 hour matched with 40Cr, the wear loss of new steel is 0.0115g, it is lower than current steel by 40%; low temperature impact work at -40℃of new steel concentrates in 60-80J, it is 2-3times of current steel. So new grade E steel have great engineering reference value to the replacement of key parts of heavy load train and broad prospects.