非调质钢连续冷却相变材料.doc

非调质钢连续冷却相变动态热模拟分析 摘 要 非调质钢由于节省了热处理工序和设备，避免了淬火变形和开裂等造成的废品，减少了污染，而且具有很好的经济效益等优势，成为了一种理想的节约能源、节省资源的经济型新材料，符合钢铁产业发展政策要求，其用途也十分广泛。 本文以中国第一汽车公司转向节用某非调质钢为研究对象，在Gleeble-2000热模拟实验机上进行了不同冷却速度的动态热模拟实验，采用热膨胀法与金相组织观察方法相结合手段，利用orgin软件绘制了该非调质钢的连续冷却转变曲线，即CCT曲线，研究了在动态连续冷却相变过程中的显微组织演变规律。 研究结果表明： （1）该钢的CCT曲线相变区主要包括高温转变区、中温转变区和低温转变区三部分。相变产物主要是铁素体、珠光体、贝氏体和马氏体。 （2）相变产物随冷却速度的改变而改变。当冷却速度小于2℃/s时，奥氏体中同时析出铁素体、珠光体和贝氏体；当冷却速度大于2℃/s小于3℃/s时，奥氏体中析出铁素体和贝氏体；当冷却速度大于3℃/s小于7℃/s时，奥氏体中只析出贝氏体；当冷却速度大于7℃/s小于20℃/s时，奥氏体同时发生贝氏体转变和马氏体转变；而当冷却速度大于20℃/s时，奥氏体只发生马氏体转变。 （3）冷却速度的提高使奥氏体向铁素体转变温度降低，贝氏体相变的相变温度先降低，当冷却速度超过1℃/s呈逐步增高的趋势。对应显微组织看出，随着冷却速度的增加使实验钢的铁素体晶粒变细，形态也由等轴状逐渐过渡为针状，贝氏体形貌也由针状铁素体演变为板条贝氏体，板条表现出细化的趋势，板条束方向趋于一致。 关键词：非调质钢；连续冷却相变；热模拟；显微组织 The dynamic thermal simulation analysis on continuous cooling phase transformation of the non-quenched and tempered steel Abstract The non-quenched and tempered steel is a kind of ideal and economic new material that saving energy and resource, it accords with the demand of the steel industry developmental policy and its use is extremely wide range, because of the non-quenched and tempered steel saves on the process and equipment of the thermal treatment, avoids the waste that created by the deformation and flaw of quenching, reduces the polluting. The research uses the non-quenched and tempered steel of steering knuckle in China First Automobile Works Group as the object, conducts a dynamic thermal simulation experiment in different cooling rate on the thermal simulation machine of Gleeble-2000, uses the means of thermal expansion combining with the means of microstructure observation, draws the continuous cooling transformation curve of the non-quenched and tempered steel by the software of orgin, which is CCT curves, studys the microstructure evolution in a dynamic continuous cooling phase transformation process. The results show that: (1)The phase transition zone in CCT curves of the steel includes the high-temperature transition zone、middle-temperature transition zone and