不同硼含量微合金钢的连续冷却相变行为

 利用热模拟试验技术对实验室制备的含硼微合金钢连续冷却转变形为进行了试验研究，利用光学显微镜研究冷却速度、变形对试验钢显微组织的影响，探讨了硼对转变行为的影响规律。结果表明：适量硼延缓多边形铁素体生成，有利于获得贝氏体组织；无硼及wB=00020%时，分别在1~25及05~25℃/s的冷速都能得到贝氏体组织；wB=00030%时，冷速在2℃/s 以上能得到贝氏体组织；与未变形相比，变形导致试验钢贝氏体冷速区间变窄。在同一冷速下，随硼含量增加贝氏体开始转变温度先降低再升高，显微硬度随硼含量增加先增加而后降低。

Continuous Cooling Transformation Behavior of Micro-Alloy Steel Under Different Boron Contents

The continuous cooling transformation(CCT) diagrams of austenite non-deformation and 40% deformation at 900 ℃ were constructed by means of thermomechanical simulator for low carbon steels containing different boron contents,OM was employed to investigate the influence of cooling rate and deformation process on the transformation microstructure,the transformation influence of boron was analyzed.The results show that the hardenability of austenite is enhanced by the addition of boron;the bainitic structure can be formed respectively with cooling rates from 1 to 25 ℃/s and 0.5 to 25 ℃/s under no boron and 0.002 0% boron,the cooling rates region for bainite decreased to at least 2 ℃/s when boron contents is 0.003 0%.Plastic deformation decreases the bainitic transformation cooling rate region by comparison of non-deformation.The bainitic starting transformation temperature decreases firstly and then increases with the increasing of boron contents;however the hardness of tested steels increases at first then decreases at the same cooling rates.