轧制工艺对铁素体基Ti-Mo微合金钢纳米尺度碳氮化物析出行为的影响

EFFECT OF CONTROLLED ROLLING PROCESSING ON NANOMETER-SIZED CARBONITRIDE OF Ti-Mo FER-RITE MATRIX MICROALLOYED STEEL

采用SEM,TEM和物理化学相分析等方法对铁素体基Ti-Mo微合金钢在2种不同轧制工艺下的析出相分布和粒度进行了观察和统计,结合热力学和动力学计算研究了γ相区变形过程中形变储能对诱导析出的影响,分析了γ相区形变诱导析出量对后续γ→α相变以及相变后α相基体中继续析出时析出相的临界晶核尺寸、相对形核率和相对沉淀开始时间的影响.结果表明,在总变形量相同的情况下,与γ相再结晶区和未再结晶区两阶段轧制相比较,采用γ相再结晶区单阶段轧制更有利于获得析出量大、尺度分布均匀的个位纳米级碳氮化物,这类碳氮化物占析出物总量的75%(质量分数).

Single nanometer sized particles, which are smaller than i0 nm, can significantly en- hance the precipitation strengthening in microalloyed steels, thus causing their strength to be promoted greatly. In order to improve the strength of the steel, it is quite necessary to get a large amount of single nanometer-sized particles through optimizing rolling technology. In this work, the effects of two different kinds of controlled rolling technologies on the size and distribution of precipitated particles in the Ti-Mo ferritie matrix microalloyed steel have been researched using SEM, TEM and small-angle X-ray scattering. The results show that with the same total rolling reduction, the steel rolled only in r phase crystallization zone can obtain a higher portion of single nanometer-sized particles than that rolled respectively in r phase recrystallization and nonrecrystallization zones, in which those single nanometer-sized particles account for about 75% （mass fraction） of whole precipitated particles. In order to study the effect of deformation potency in r phase zone on the amount of precipitates in phase and the micro-crystal size, nucleation rate and incubation time of following precipitates in r→α transformation and ferritie matrix after r→ transformation, some thermodynamics and kinetics calculations and analysis on precipitation are also conducted.