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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。
The Q420E steel was prepared from Q345D continuous casting billets (0.16C, 0.26Si, 1.40Mn, Nb + Ti <0.040). The thick 30 mm Q420E high strength steel plate was tested by fast cooling with different cooling rate and final cooling temperature. Effect of Cooling Rate and Final Cooling Temperature on Its Strength and Toughness. The results show that with the increase of the cooling rate and the decrease of the final cooling temperature, the grain size of the ferrite decreases, the strength and toughness of the steel plate increase, and the elongation decreases. When the final cooling temperature is controlled between 480 and 520 ℃, When the speed is between 8 ℃ and 15 ℃ / s, the microstructure is ferrite + pearlite + bainite, and the heart ferrite grain size is 7.2μm. The comprehensive performance of the steel plate meets the requirements of national standard Q420E level, and the success The Q345D low-cost production of 30-mm-thick Q420E plates is achieved and provides a basis for the performance improvement of higher-grade grades, but the segmental segregation of some of the plates during the rolling process, as well as the rapid cooling process, The impact of performance still needs further study.