以厚度为55 mm的高强度钢Q800厚板为研究对象, 分析了热轧态与调质态钢板的组织、性能以及析出物形貌。结果表明: 热轧态钢板在板厚1/4处的组织中有发达的板条贝氏体和粒状贝氏体, 板厚1/2处的组织为粒状贝氏体和多边形铁素体, 大量M/A岛存在基体中; 调质态钢板中M/A岛数量大幅减少, 边部板条组织更加粗大, 心部组织为块状铁素体和粒状贝氏体; 与热轧态试验钢相比, 调质态试验钢的抗拉强度和屈服强度都降低, 伸长率显著提高, 横截面上的硬度波动较小; 试验钢中的析出物主要为铌和钛的碳氮化物, 热轧态钢中析出物的数量较少, 调质态钢中析出物的数量较多, 且部分析出物尺寸有长大的趋势。

Taking high strength steel Q800 thick plates with thickness of 55 mm as research objects, the microstructure, properties and precipitation morphology of the tested steel in hot-rolled state and quenched and tempered state were analyzed. The results show that there were large amounts of lath bainites and granular bainites at 1/4 thickness of hot-rolled steel, the microstructure at 1/2 thickness were granular bainite and polygonal ferrite, and a large number of M/A islands existed in matrix. After quenching and tempering, M/A islands decreased sharply, lathes on the edge were thicker and the microstructure in the center were massive ferrite and granular bainite. Both tensile strength and yield strength of quenched and tempered steels dropped, but the elongation increased notably, and there was little change in hardness at cross section. Precipitations in the tested steel mainly were carbonitrides containing Nb and Ti, and the amount of precipitations in hot-rolled steel was few but increased in quenched and tempered steel and parts of them had a trend of growing up.