三种不同硅含量的6CrNiMnSiMOV钢过冷奥氏体等温转变研究

ISOTHERMAL TRANSFORMATION OF SUPERCOOLED AUSTENITE IN 6CrNiMnSiMoV STEEL WITH THREE DIFFERENT Si-CONTENTS

本文采用膨胀式自动相变仪Formastor—F配合金相显微分析,测定了不同硅含量的高强度低合金冷作模具钢6CrNiMnSiMoV(代号GD钢)的过冷奥氏体等温转变曲线(TTT),并根据TTT制定了三种钢的等温淬火处理工艺,测定了三种钢等温淬火后的各项力学性能。结果表明,提高钢的硅含量,钢的加热相变点上升,Ms稍有下降;硅缩短等温珠光体转变孕育期,并使珠光体转变线上移;硅抑制等温贝氏体转变,使贝氏体转变线下移;GD钢等温淬火后获得马氏体-下贝氏体组织,1.82％Si的GD_4钢等温淬火后具有最佳的力学性能。

The TTT curves of high strength-toughness low alloy cold die steel 6CrNiMnSiMoV (it is called GD steel) with three different Si-contents were determined by means of dilatometrie method using Formastor-F, in cooperation with mierostructure analysis. The isothermal treatment process was determined according to the TTT curves, the mechanical properties of GD steel austempered were measured. The results show that: as the content of silicon in steel increases, the heating transformation point increases and the Ms deere.ases slightly; the incubation period of pearlite isothermal transformation shortens, the pearlite transformation line shifts to upward; bainite isothermal transformation is checked, the bainite transformation line shifts downward; GD steel appears duplex mierostrueture of martensite and lower bainite after austempered. GD, steel that contains 1.82％ silicon exhibits best mechanical properties.