SANS study of the random VC precipitation kinetics in Nanosteels

Nano-steels are a new generation of Advanced High Strength Steels (AHSS), extremely suitable for lightweight automotive applications. The matrix of the steel, which provides ductility and stretch, is significantly strengthened by manometer-sized precipitates, which can increase the strength level by 30-50%. These steels contain different micro-alloying additions, such as vanadium (V) and molybdenum (Mo), which form the essential nano-precipitates. A resource-efficient use of these alloying additions requires further knowledge on the formation kinetics of these nanometer-sized vanadium carbides (VC). The formation of these nano-scale VC precipitates can be achieved by two mechanisms: (a) random precipitation from supersaturated ferrite and/or (b) interphase precipitation. Our previous studies have focused on interphase precipitation. In this experiment we want to explore random precipitation. Our aim is to measure the random VC-precipitation kinetics in NANO-steel by SANS and elucidate the effects of V addition.

纳米钢是新一代先进高强度钢（Advanced High Strength Steels，AHSS），极适用于汽车轻量化应用。赋予钢材延展性与拉伸性能的基体，可通过纳米级析出相显著强化，强度提升幅度达30%-50%。此类钢材含钒（V）、钼（Mo）等微合金添加元素，这些元素是形成关键纳米析出相的核心成分。为实现合金元素的资源高效利用，需进一步明晰纳米级碳化钒（VC）的形成动力学机制。纳米级VC析出相的形成可通过两种机制实现：（a）从过饱和铁素体中随机析出；（b）相间析出。我们此前的研究聚焦于相间析出机制，本实验则旨在探究随机析出过程。研究目标是通过小角中子散射（Small Angle Neutron Scattering，SANS）测定纳米钢中VC的随机析出动力学，并阐明钒添加量的影响。