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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。
The change of the volume fraction of retrograde austenite and its precipitation regularity during the aging process of a ultrahigh strength martensitic stainless steel were studied. The kinetic curves (TTA) of the same amount of transformation were obtained. The results show that the minimum temperature for the formation of reverse austenite in the experimental steel is 450 ℃, whereas when the aging temperature is equal to or greater than 650 ℃, the retrograded austenite will undergo secondary martensite phase , The shortest time for the formation of reverse transformation austenite at 540 ℃ is 11.5 min, and after the treatment at 540 ℃ for 4 h, the transformation austenite is formed in the experimental steel by 11.0%, the strength can reach 1940 MPa, the fracture toughness Above 100 MPa.m1 / 2, the film-like retrogressive austenite precipitates along the boundaries of the martensite slab or precipitates along the original austenite grain boundaries, which plays an important role in improving the ductility of the steel.