低碳Mn-Nb-Ti钢中的粒状贝氏体组织

Granular Bainite Microstructures in Low Carbon Mn-Nb-Ti Steel

运用透射电镜研究了低碳Mn-Nb-Ti钢中出现的粒状贝氏体组织。结果表明,在1200℃加热空冷正火时获得条型粒状贝氏体组织,而在1200℃加热于550℃等温处理时得到块型粒状贝氏体组织。前者是在具有板条亚结构的铁素体基体上分布着(M-A)小岛,后者是在块状铁素体基体上分布着由退化珠光体和(M-A)所组成的混合岛状物。本文对粒状贝氏体的形成机制也作了一些探讨。

Granular bainite microstructures in low carbon Mn-Nb-Ti steel have been studied with. TEM. The results showed that the microstructure is acicular granular bainite when the specimen are heated at 1200℃ and then air-cooled. Massive granular bainite will appear when the steel is austenitized at 1200℃ and then isothermally treated at 550℃. The acicular granular bainite consists of acicular ferrite and (M-A) islands, the massive granular bainite is mixed islands of degenerated pearlite and (M-A) on the massive ferrite matrix. The transformation mechanisms of the microstructures have also been discussed.