硅质量分数对CSP生产DP600相变规律及工艺的影响

基于C Si Mn Cr Mo系600 MPa级热轧双相钢的组分，设计了不同硅质量分数(0.55%和1.17%)的两种试验钢。采用Gleeble 3500热模拟试验机测定了两种试验钢的连续冷却转变曲线，分析了硅质量分数对试验钢连续冷却过程中组织转变的影响，并研究了硅质量分数对短流程生产中温卷取型热轧双相钢生产工艺的影响。结果表明，相对于w(Si)=1.17%，w(Si)=0.55%使铁素体开始转变温度降低40~50 ℃，明显缩短了铁素体转变的孕育期，并增加了铁素体的体积分数。在CSP线上生产时，低硅钢的终轧温度可控制为820~830 ℃，低的终轧温度使铁素体相变时间增加2.2 s左右，铁素体转变量增加，且后续相变过程中可避免非马氏体组织的出现。因此，低硅钢适合在CSP短流程线上生产中温卷取型热轧双相钢。

Effect of mass fraction of Si on transformation rule #br# and process of producing DP600 in CSP

 Based on the component of C Si Mn Cr Mo hot rolled dual phase steel of 600 MPa grade, two test steels with different mass fraction of Si (0.55% and 1.17%) were designed. The CCT curves of the two test steels were measured by Gleeble 3500 thermal mechanical simulator. The effect of mass fraction of Si on the phase transformation evolution of the test steels during the continuous cooling process was analyzed, and the effect of mass fraction of Si on the production process of medium temperature coiling hot rolled dual phase steel in short process was studied. The results showed that compared with w(Si)=1.17%, w(Si)=0.55% reduced the ferrite transformation temperature by about 40 50 ℃, significantly shortened the incubation period of ferrite transformation and increased the volume fraction of ferrite. In the actual production of CSP line, the finishing temperature of the low Si test steel can be controlled in 820 830 ℃. The low finishing temperature increased the ferrite phase transformation time by about 2.2 s and the amount of ferrite transformation. Moreover, the occurrence of non martensite microstructure can be avoided in the subsequent phase transformation process. Therefore, the low Si test steel was suitable for the production of medium temperature coiling hot rolled dual steel on the compact thin slab production line.