采用透射电镜与能谱仪研究了960 MPa级铌钛微合金化超高强钢在不同加热温度及保温时间下第二相粒子的溶解行为。结果表明：试验钢中含有凝固过程中析出的尺寸大于1 μm的方形TiN粒子，在锻造过程中应变诱导析出的尺寸为200 nm~1 μm的方形、椭球形TiS或Ti（C，S）粒子及尺寸小于500 nm的方形、球形、椭球形（Nb，Ti）（C，N）析出相；随着加热温度的升高，第二相粒子的数量减少，尺寸增大，随着保温时间的延长，小尺寸第二相粒子的数量减少，大尺寸第二相粒子的数量增加且其棱角变得模糊，这些粒子均为铌与钛的复合析出物；为保证铌、钛的碳氮化物能够充分溶解于奥氏体中并具有合适的奥氏体晶粒尺寸，960 MPa级铌钛微合金化超高强钢合适的加热温度为1 250℃，保温时间为80 min。

The dissolution behavior of second phase particles in 960 MPa grade Nb-Ti microalloyed ultra-high strength steel after heat treatment at different temperatures for different times was studied by transmission electron microscope and energy dispersive X-ray analyzer. The results show that the test steel contained square TiN particles with size greater than 1 μm precipitated during solidification, square and ellipsoidal TiS or Ti (C, S) particles with size of 200 nm-1 μm, and square, spherical and ellipsoidal (Nb, Ti) (C, N) precipitates with size less than 500 nm precipitated by strain during forging. With the increase of heating temperature, the number of the second phase particles decreased and the size increased. With the extension of holding time, the number of the small second phase particles decreased, while that of large second phase particles increased and whose edges became blurred. These particles were composite precipitates containing niobium and titanium. Considering the full dissolution of carbonitride containing niobium and titanium and the suitable grain size of austenite, heating at 1 250℃ for 80 min was relatively appropriate for 960 MPa grade Nb-Ti microalloyed ultra-high strength steel.