薄板坯连铸连轧工艺对铌微合金化高强度钢组织和性能的影响

EFFECT OF THIN SLAB CONTINUOUS CASTING AND ROLLING PROCESS ON THE MICROSTRUCTURE AND PROPERTIES OF Nb MICROALLOYED HIGH STRENGTH STEEL

首先建立薄板坯连铸连轧工艺的试验室模拟技术 ,并运用该模拟技术 ,研究薄板坯连铸连轧工艺(CSP)和传统板坯再加热工艺 (TRP)两种工艺对铌微合金化高强度钢的显微组织和力学性能的影响。研究结果表明 :CSP钢的晶粒细化效果不如 TRP钢 ,两者的平均铁素体晶粒尺寸分别为 8.17μm和 6 .30 μm。在CSP试验钢板中铌的析出量较大 ,特别是在铁素体中细小颗粒的铌的析出物较多 ,沉淀强化效果较强。 CSP试验钢的 σ0 .5和 σb 分别较 TRP工艺低约 4 0 MPa和约 2 5 MPa,同时其低温冲击韧性较好 。

The laboratory simulation technique of CSP was built first. The influences of thin slab continuous casting and rolling process (CSP) on the microstructure and mechanical properties of Nb microalloyed high strength steel have been studied by using the laboratory simulation technique. For comparison, the microstructure and mechanical properties of steel strip produced by simulated traditional rolling process (TRP) have also been studied. Results show that the average ferrite grain size of CSP steel is larger than that of TRP steel (8 17 μm and 6 30 μm respectively). The precipitation of Nb in the CSP final product is much stronger than that in the TRP final product. Results also show that the strength of CSP steel is lower than that of TRP steel; σ 0 5 and σ b of CSP steel is about 40 MPa and 25 MPa lower than those of TRP steel respectively. The CSP steel shows at the same time better impact toughness and lower FATT.