It is of great significance to develop new types of shipbuilding steel with ultra-high strength,good toughness,and ex-cellent welding performance to meet the development requirements of large-scale and lightweight ships,and to achieve efficient production.Scanning electron microscopy,electron backscatter diffraction,and transmission electron microscopy were used to study the effects of direct quenching(DQ)and reheat quenching(RQ)processes on the microstructure and properties of nanoscale Cu-NiAl co-precipitation strengthened ultra-high strength steel.The results show that the microstructures of both DQ and RQ steels consist of lath martensite.After 550 ℃ annealing,the DQT steel forms a finer lath martensite microstructure and higher dislocation density,providing more nucleation sites for the high-density precipitation of Cu-NiAl phase.Compared with RQ steel,DQ steel has higher annealing stability,retaining a higher density and a higher proportion of small angle grain bounda-ries after annealing.Therefore,under the combined action of more pronounced precipitation strengthening and fine grain strengthening,the DQ steel exhibits higher strength after annealing,with a yield strength that is 100 MPa higher than that of RQT steel,reaching 1 425 MPa.
关键词
直接淬火/超高强钢/纳米Cu-NiAl复合析出相/回火稳定性/小角度晶界/组织性能/高效生产
Key words
direct quenching/ultra-high strength steel/nanoscale Cu-NiAl co-precipitation phase/tempering stability/small an-gle grain boundaries/microstructure and properties/efficient production
维普
万方数据