Nb和Mo对矿用磨球用钢微结构和相变的影响

对不同合金成分磨球用钢样品进行高温激光共聚焦显微镜(HT-CLSM)原位观察和JMatPro软件模拟计算,研究了Nb、Mo元素对其热处理过程中微结构和相变的影响。结果表明,试验钢中添加0.051%Nb元素的原奥氏体平均晶粒尺寸最小(38.8 μm),添加0.079%Mo元素的次之,无添加的最大,可达74.1 μm。添加Nb元素时,析出物类别主要为Nb(C, N)和MnS,析出物的数量最多,显著阻碍了高温奥氏体晶粒长大。添加Mo元素时,析出物类别主要为MnS和AlN,析出物数量次之,对奥氏体晶粒长大有一定的阻碍作用。Nb和Mo元素的添加均有利于扩大贝氏体转变区,增加贝氏体转变量,提高马氏体转变开始温度。

Effect of Nb and Mo on microstructure and phase transformation of steel for mining grinding balls

Effect of Nb and Mo on microstructure and phase transformation of grinding ball steel with different alloy composition during heat treatment was studied by using high temperature confocal laser scanning microscope (HT-CLSM) and JMatPro simulation calculation. The results show that the average austenite grain size of the tested steel with 0.051%Nb is the smallest (38.8 μm), that without Nb or Mo addition is the largest (74.1 μm), and that with 0.079% Mo is the intermediate. With Nb element addition, the precipitates are mainly Nb(C, N) and MnS, and the amount of precipitates is the most, which significantly hinder the grain growth of high temperature austenite. While with Mo element addition, the precipitates are mainly MnS and AlN, and the amount of precipitates is the intermediate, which slightly hinder the grain growth of austenite. The addition of Nb and Mo is beneficial to expand the bainite transformation zone, increases the percentage of bainite transformation and increases the martensite transformation start temperature.