Si含量对高碳贝氏体钢微观组织与性能的影响

Effect of Si content on microstructure and properties of high carbon bainitic steel

以4种不同Si含量的高碳贝氏体轴承钢为研究对象,在相同热处理条件下,通过热膨胀相变仪、X射线衍射仪、扫描电镜和透射电镜等技术研究Si含量对高碳贝氏体轴承钢相变、组织特征及力学性能的影响。结果表明,Si能够延长高碳贝氏体轴承钢贝氏体转变孕育期,降低贝氏体转变速率并提高Ac_(1)、Ac_(cm)温度。随着钢中Si含量的增加,高碳贝氏体轴承钢中残留奥氏体体积分数增大,但贝氏体铁素体板条尺寸减小;当Si含量达到1.4%时,贝氏体铁素体板条尺寸达到纳米级且板条内无碳化物析出。力学性能结果表明,高碳贝氏体轴承钢硬度随Si含量的增加而降低,冲击性能随Si含量的增加而升高,Si含量为1.4%时高碳贝氏体轴承钢具有最佳的综合力学性能。

Four kinds of high carbon bainitic bearing steels with different Si contents were designed.Under the same heat treatment condition,the effect of Si content on phase transformation,microstructure characteristics and mechanical properties of the high carbon bainitic bearing steels was studied by means of thermal expansion phase change meter,X-ray diffractometer,scanning electron microscope,transmission electron microscope techniques.The results show that Si can prolong the bainite transformation incubation period,decreases the bainite transformation rate and increase the phase transformation points of Ac_1,Ac_(cm) of the high carbon bainitic bearing steels.With the increase of Si content in the high carbon bainitic bearing steels,the volume fraction of retained austenite of the high carbon bainitic bearing steels increases,but the size of bainitic ferrite lath decreases.When the Si content reaches 1.4%,the size of bainite ferrite lath reaches nanometer level and no carbides precipitates in it.The results of mechanical properties show that the hardness of the steels decreases with the increase of Si content,and the toughness increases with the increase of Si content.The steel with the Si content of 1.4% has the best comprehensive mechanical properties.