【摘要】 研究了一种超高强度马氏体时效不锈钢在时效过程中逆转变奥氏体的体积分数的变化及其析出规律,并得到相同转变量下的动力学曲线(TTA)。结果表明,实验钢生成逆转变奥氏体的最低温度为450℃,而当时效温度等于(或大于)650℃时所生成的逆转变奥氏体将在冷却过程中发生二次马氏体相变,在540℃时效生成逆转变奥氏体最短时间为11.5 min,经过540℃×4 h处理后实验钢中生成11.0%的逆转变奥氏体,此时强度可达到1940 MPa,断裂韧度大于100 MPa.m1/2,薄膜状逆转变奥氏体沿马氏体板条界上非连续析出或沿着原奥氏体晶界析出,对改善钢的韧塑性起到了重要的作用。更多还原

【Abstract】 Precipitation behavior and transformation kinetics of reverted austenite in an ultra-high strength maraging stainless steel was investigated.Based on the characteristics of linear relationship between volume fraction of the reverted austenite and isothermal time during initial stage of aging process,the dynamic curves at the same transformation amount were obtained.The results show that no reverted austenite is observed in the steel when the aging temperature is lower than 450 ℃,and secondary martensitic transformation occurs when the aging temperature is above 650 ℃.With the increase of aging temperature,the time for reverted austenite precipitation is shortened.After aging at 540 ℃ for 11.5min,austenite begins to precipitate,and aging at 540 ℃ for 4 h,11.0% volume fraction of reverted austenite precipitates in the steel.The strength of the steel aged at 540 ℃ for 4 h reaches up to 1940 MPa,and its fracture toughness(KIC) reaches up to 100 MPa.m1/2.The thin reverted austenite precipitated at the boundaries of lath martensite and prior austenitic grains improves toughness and plasticity of the steel.更多还原