铁素体基Ti-Mo微合金钢超细碳化物析出规律

Precipitation law of ultra fine carbides in ferrite matrix Ti-Mo micro-alloy steel

利用光学显微镜、透射电镜和能谱分析等方法对两种不同Ti含量的铁素体基Ti--Mo微合金钢中析出相的尺寸、分布特征、析出规律和成分进行了研究.结果表明:钢中绝大多数析出相为超细碳化物,尺寸小于10 nm,析出相尺寸呈正态分布.随着Ti质量分数由0.072%增到0.092%,析出粒子平均尺寸增大,分布峰值向粒子尺寸增大的方向移动.Ti--Mo微合金钢具有栅格状的相间析出方式,栅格间距受冷速的影响较大,晶内和靠近晶界处的栅格间距不同.能谱分析发现,不同尺寸的粒子Mo含量不同,较大颗粒(50 nm左右)析出相中不含Mo,小颗粒(<20 nm)中碳化物是Ti和Mo的复合析出相,且随着粒子尺寸的减小,成分中Mo所占比重增大.

The size, distribution characteristics, precipitation law, and composition of precipitate particles in ferrite matrix Ti-Mo micro-alloy steel with two different titanium contents were studied by metallographic microscopy, transmission electron microscopy and energy dispersive spectroscopy. Most of the precipitate particles are ultra fine carbides of less than 10 nm in size, and the particle sizes are a normal distribution. With the increase of titanium content from 0. 072% to 0. 092% , the average particle size increases and the distribution peak gradually moves to the particle size increasing direction. The Ti-Mo micro-alloy steel has an inter-phase precipitation style like ledge structures. The ledge spacing in the interior grain is different from that near the grain boundaries, and it is affected by cooling rate. Energy spectrum analysis shows that the Mo content is different in different sizes of particles. The composition of the bigger particles （about 50 nm） has no molybdenum, but the smaller particles （less than 20 nm） are compound of Ti and Mo. The Mo content increases with the particle size decreasing.