薄板坯连铸连轧生产含硼低碳热轧带钢的软化机理

SOFTENING MECHANISM OF BORON-BEARING LOW-CARBON HOT STRIPS PRODUCED BY TSCR ROUTE

通过薄板坯连铸连轧(TSCR)生产典型低碳铝镇静钢SPHC(一般用热轧钢带)流程的实验室模拟,分析了含(10- 50)×10-6 B,0．005％N热轧钢带的组织、析出物的特点以及性能变化．结果表明:由于粗大BN的优先析出抑制了细小AIN的析出,提高了晶粒的生长能力,以及B在奥氏体晶界的偏聚抑制了铁素体形核,使得含B热轧钢带晶粒明显粗化,通过测定,含B钢晶粒度达到7-8级,平均晶粒尺寸达到25μm．含B钢晶粒粗化以及钢中AlN析出量和自由N含量的降低,使得热轧钢带屈服强度与无B钢相比降低约94 MPa．

The steel plate heat commercial （SPHC） hot strips containing （10-50）× 10^-6 B and 0.005% N were produced simulatively by thin slab casting ＆ rolling （TSCR） production route in the laboratory, and the effects of boron micro-alloying on the microstucture,precipitates and mechanical properties were investigated. The results showed that owing to the substitution of large size BN for fine AlN, which improved the grain growing ability, and the segregation of boron on austenite grain boundary, which retarded the transformation from austenite to ferrite, the ASTM graindegree of the hot strips can reach 7-8 grade, corresponding to the mean ferrite grain size of 25μm, The ferrite grain coarsening, and the reductions of AlN precipitation strengthening and N solution strengthening make the yield strength decrease by 94 MPa, compared with the B free steel.