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通过组织观察与力学性能测试,分析了X80管线用钢板轧后开始冷却温度(SCT)对其组织与性能的影响。研究结果表明,当开始冷却温度在680~785℃温度范围内时,不改变钢板的合金成分,钢板的强度指标不低于X70管线钢的要求,并具有良好的低温冲击性能,-20℃冲击吸收能量最低值不小于280 J。开始冷却温度对钢板的显微组织有明显的影响,当开始冷却温度为785℃与750℃时,显微组织以贝氏体为主;当开始冷却温度为715℃与680℃时,显微组织为铁素体、贝氏体复合组织为主。组织中含有一定体积分数的铁素体,可以改善钢板的塑性,但会在一定程度上降低强度与冲击性能。
The microstructure and mechanical properties of X80 steel sheets after rolling were analyzed by microstructure observation and mechanical properties test. The results show that when the cooling temperature is in the range of 680 ~ 785 ℃, the alloy composition is not changed, the strength index of the steel plate is not lower than the requirements of X70 pipeline steel, and has good low temperature impact performance, -20 ℃ impact The lowest absorbed energy is not less than 280J. The initial cooling temperature had a significant effect on the microstructure of the steel. When the starting cooling temperature was 785 ℃ and 750 ℃, the microstructure was dominated by bainite. When the cooling temperature was 715 ℃ and 680 ℃, Tissue ferrite, bainitic composite tissue-based. Tissue containing a certain volume fraction of ferrite, can improve the plasticity of steel, but to some extent, reduce the strength and impact properties.