Q350EWR1高耐蚀钢板组织和耐大气腐蚀性能研究

当前,对铁路车辆用钢耐大气腐蚀性能的要求越来越严苛。采用高Cr成分体系和轧后两段冷却工艺,试制了Q350EWR1铁路车辆用高耐蚀钢。研究了其奥氏体连续冷却相变行为,获得了不同冷却速率下其组织演变规律。开展了轧制工艺对Q350EWR1耐蚀钢组织和性能影响的研究,并对其腐蚀性能进行了评价。结果表明,当冷速为0.1 ℃/s时,耐蚀钢组织由铁素体和珠光体组成;当冷速为0.5 ℃/s时,组织由铁素体、珠光体和少量贝氏体组成;当冷速大于1 ℃/s时,组织为单一贝氏体组织,这是由于高Cr成分提高了钢的淬透性,使得较低冷速下发生贝氏体相变而导致。研发的耐蚀钢综合力学性能优良,其屈服强度360~420 MPa,抗拉强度550~640 MPa,屈强比不大于0.66,伸长率不小于27%,-40 ℃冲击功大于280 J,耐大气腐蚀性能相对于Q345B钢的失重率小于30%。

Research of microstructure and atmospheric corrosion resistance property of extra-weathering Q350EWR1 plate

At current,the requirements for atmospheric corrosion resistance of railway vehicle steels are becoming more and more stringent.The Q350EWR1 high corrosion resistant steel for railway vehicles was trial-produced by adopting the high Cr content system and the two-stage cooling process after rolling.Its austenite continuous cooling phase was studied,and the microstructure evolution law under different cooling rates was obtained.The effect of rolling process on the microstructure and performance of Q350EWR1 corrosion-resistant steel was studied too,and its corrosion performance was evaluated.The results show that when the cooling rate is 0.1 ℃/s,its microstructure is composed of ferrite and pearlite;when the cooling rate is 0.5 ℃/s,its microstructure is composed of ferrite,pearlite and a small amount of bainite; when the cooling rate is greater than 1 ℃/s,its microstructure is a single bainite structure.This is because the high Cr content improves the hardenability of the steel,which causes the bainite transformation to occur at a lower cooling rate.The developed steel has excellent comprehensive mechanical properties,with yield strength of 360-420 MPa,tensile strength of 550-640 MPa,yield ratio of not more than 0.66,elongation of not less than 27%,impact energy of more than 280 J at -40 ℃,and atmospheric resistance corrosion performance relative to the weight loss rate of Q345B steel is less than 30%.