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通过热膨胀仪和Gleeble3500热模拟试验机检测X70钢的膨胀系数、高温屈服强度和弹性模量,采用Marc有限元软件计算了热轧带钢在层流冷却中卷取温度分别为500、550和600℃时的温度场、相变体积分数、残余应力随时间的变化.结果表明:层流冷却过程中,在水冷前期带钢边部的应力超过了该温度下钢板的屈服强度,带钢板形会向着边浪发展;水冷结束时,边部应力值再次超过屈服强度并发生了塑性变形,带钢板形会向着中浪发展.在保证X70管线钢性能的条件下,降低卷取温度有利于钢板贝氏体相变的完成和层流冷却阶段残余应力的降低.
The thermal expansion coefficient and high temperature yield strength and elastic modulus of X70 steel were measured by thermal dilatometer and Gleeble3500 thermal simulation tester. The hot rolling steel strip was coiled at temperatures of 500, 550 and 600 ℃ .The results show that the stress at the edge of the strip at the early stage of water cooling exceeds the yield strength of the strip at the temperature of the laminar cooling, To the edge of the wave development; water-cooled at the end, the edge stress again exceeds the yield strength and plastic deformation occurs, the strip shape will be to the waves of development.In ensuring X70 pipeline steel conditions, lower coiling temperature is conducive to the shellfish The completion of the martensitic transformation and the reduction of the residual stress in the laminar cooling stage.