V和V-N微合金化低碳钢碳氮化物的形变析出

通过热模拟压缩实验考察了V和V-N微合金化低碳锰钢在860~740℃范围内多道次变形时的组织演变和碳氮化物析出规律及其相互影响.结果表明,含V钢中添加少量的N促进了变形奥氏体中V的碳氮化物(尤其是氮化物)的析出和形变诱导铁素体相变.V的碳氮化物析出降低了奥氏体中固溶的V,从而减弱了固溶V对形变诱导铁素体相变的抑制作用.碳氮化物析出在奥氏体的局部区域造成贫碳区,也促进了铁素体形核.在相同处理工艺下与V钢相比,V-N钢中铁素体内碳氮化物开始析出的时间短,析出相的数量多,长大速度慢,分布弥散.

Precipitation Behavior and Effects of Vanadium Carbonitride in V and V-N Microalloyed Mild Steel During Multi-Pass Deformation

The microstructure evolution and precipitation behavior of vanadium carbonitride were examined using a Gleeble 1500 thermal simulator, as well as their mutual effect in V and V-N microalloyed mild steel (0.1%C-1.0%Mn) during multi-pass deformation at 860-740°C. The result showed that adding a small amount of N to V microalloyed steel will expedite the precipitation of V(C, N), especially V-N in deformed austenite, and the deformation induced ferrite transformation (DIFT). But the concentration of V dissolved in austenite decreases because of the precipitation of V(C, N), thus weakening the effect of V on suppressing DIFT so as to expedite the ferrite nucleation. Moreover, the precipitation of V(C, N) causes locally the formation of carbon-poor region in austenite, thus expediting the ferrite nucleation further. Comparing with the V microalloyed steel under the same treatment conditions, the precipitation of V(C, N) within ferrites in V-N microalloyed steel requires shorter inoculation time with higher V(C, N) volume fraction, lower growth rate and wider dispersion.