Abstract: The characteristics of structure and grain, yield strength -ultimate tensile strength(YS-UTS)xatio,and c longation of 2.0～12.7 mm steel Q345B strip produced by CSP process(71 mm cast slab)and conventional process(250 mm cast slab)have been analyzed by quantimet and statistic of product mechanical properties.The results indicated that the grain size of strip produced by CSP process was7.03~8.78 μm,grain size rating 11.5～12.0,average YS-UTS ratio 0.77 and elongation 27.8% which were higher than that by conventional process(respectively8.79～8.95 μm,10.0~ 10.5,0.72 and 25.0%).Calculated results show that the contributions of fine grain strengthening and precipitation strengthening of low carbon steel strip produced by CSP process make up 59% of all strengthening factors,while that by conventional process make up 55% of all factors.

Key words: CSP Process, Q345B Steel Strip, Structure, Mechanical Properties

摘要： 通过定量金相和产品力学性能统计分析了CSP工艺(71 mm铸坯)和常规工艺(250 mm铸坯)生产的 Q345B钢2.0~12.7mm板卷组织和晶粒特征、屈强比(YS-UTS)和延伸率。结果表明，CSP工艺生产的板卷的晶粒 尺寸为7.03~8.78 μm,晶粒度级别11.5～12.0,平均屈强比为0.77,延伸率为27.8%,较常规工艺生产的板卷高 (分别为8.79~8.95 μm,10.0～10.5,0.72和25.0%)。计算结果表明，CSP热轧低碳钢板卷细晶强化和沉淀强化占59%,常规工艺该项占55%。

关键词: CSP工艺, Q345B钢带, 组织, 力学性能