精炼和热轧工艺对热轧带钢SPHC组织性能的影响

Influences of refining and rolling process on microstructure and properties of hot rolled strip SPHC

采用工业试验方法,研究了精炼工艺和轧钢工艺对SPHC热卷板组织性能的影响。结果表明,与RH精炼相比,LF精炼形成的夹杂物数量明显增加,同时形成的夹杂物更易成为裂纹源,故生产结构用SPHC热卷板时可采用LF工艺或RH工艺,而生产冲压用SPHC热卷板时建议采用RH工艺。终轧温度和卷取温度对SPHC热卷板组织影响较大,钢板横截面组织因终轧温度和卷取温度差异而不同。终轧温度和卷取温度较低时,钢板边部和表面易形成混晶组织,提高终轧温度至890℃,可将混晶组织控制在边部40 mm范围内。在合理终轧和卷取温度前提下,采用两阶段冷却可保证等轴铁素体晶粒的适度长大和固溶C析出,有利于提高钢板的冲压性能。

The influences of refining and rolling process on the microstructure and properties of hot rolled strip SPHC were studied by industrial tests. The results show that compared with the RH refining,the amount of inclusions formed in the plate produced by the LF refining is obviously increased,and these inclusions are more likely to be the source of cracks. Therefore,the LF or RH refining can be used to produce SPHC hot rolled structural plate,and the RH refining is recommended to produce SPHC hot rolled stamping plate. Finish rolling temperature and coiling temperature have significant impacts on the microstructures and properties of SPHC hot rolled strip. However,the cross section microstructure in the SPHC hot rolled strip depends on finish rolling and coiling temperatures,and heterogenous grains are easily formed in the surface and edge areas of the strip when finish rolling and coiling temperatures are low. By increasing finish rolling temperature to 890 ℃,heterogenous grains can be controlled within the range of 40 mm from the edge. Thus,under the condition of appropriate finish rolling temperature and coiling temperature,the two-stage cooling ensures a sufficient growth of equiaxed ferrite grains and C precipitation,which is beneficial for improving the stamping performance of steel.