【摘要】 利用Q345D连铸坯料(0.16C,0.26Si,1.40Mn,Nb+Ti<0.040)制备Q420E钢,采用不同冷却速率和终冷温度的快冷工艺进行了厚30 mmQ420E钢高强度板试验,研究了冷却速率和终冷温度对其强度及韧性的影响。结果表明,随着冷却速率的增大和终冷温度的降低,铁素体晶粒尺寸减小,钢板强度和韧性提高,伸长率下降;当终冷温度控制在480~520℃之间,冷却速度控制在8~15℃/s之间时,组织为铁素体+珠光体+贝氏体组织,心部铁素体晶粒尺寸为7.2μm,钢板综合性能达到国标Q420E级别的要求,成功实现采用Q345D轧制30 mm厚的Q420E钢板的低成本生产,并为更高级别钢种的性能提升提供了依据,但轧制过程中部分钢板出现了心部偏析,以及快冷工艺对于钢板焊接性能的影响,仍然需要做进一步研究。更多还原

【Abstract】 Steel plates with 30 mm gauge thickness were produced by using CR + FC( control rolling + fast cooling) process with Q345D continuous cast slabs. The effects of cooling rate and finish cooling temperature on strength and toughness of the plates were studied. The results reveal that,when cooling rate increasing or finish cooling temperature decreasing,the ferrite grain size and elongation of the steel decrease. However,the strength and toughness increase. With cooling rate of 15 ℃ / s and finish cooling temperature of 480- 520 ℃,the steel conforms to national standard for Q420E steel,which provides fundamentals for performance improvement of higher strength steels. Finally,segregation in the plate center is observed and the influence of fast cooling on plate welding performance needs to be further studied.更多还原