本文测定了4oCrMnSiMoV钢经贝氏休等温淬火后残余奥氏体(以下简称AR)的回火转变动力学，观察了回火时的组织变化，研究了AR回火时的热穗定性以及在静态和动态(多次冲击)拉伸时机械稳定性与回火温度的关系。结果表明:AR的回火TTT曲线由上、下两都分组成，其间有一ARR的稳定区，下部的曲线呈C型随回火温度升高，AR的热稳定性呈现先降后升、复又下降的马鞍型变化规律，而机械稳定性无论在静态或动态拉伸时均呈现先升后降的变化规律,AR机械稳定性的高低主要取决于其含碳量。在对应AR具有最高机械稳定性的温度回火，钢可获得最佳的强韧性。

The effect of tempering on stabili'y of retained austenite in 40CrMnSiMoV steel,subjected to austempering at 310℃ for holding 12 min,is investigated in this paper, The experiments carried out include determination of tempering transformation kinetics of retained austenite(AR),examination of micro-structures after temfering, and the study of stability of AR during tempering, the relationship between the mechanical stability of AR and tempering temperature under static and dynamic (repeated impact) stretch strain.The results indicate that, the TTT-Curve of AR consists of two strain.The results indicate that, the TTT-Curve of AR consists of two parts,i, e.upper part and lower part, between which there is a stable zone (375~475℃),the lower part with C-shape is similar in shape to TTT-Curve of overcooling austenite.The variation of thermal stability of AR with tempering temperature displays the curve like a saddle in shape, It means that,with increasing tempering temperature, the amount of AR decreases at first, and then increases, finally decreases again, As the tempering temperature increases,the mechanical stability of AR under static and dynamic stretch strain increases at first,and then decreases. The change of mechanical stability of A,depends mainly on its carbon content, The optimum combination of strength and toughness for this steel can be obtained by tempering at 260~280℃ as the mechanical stability of AR is the highest.