Development of 80 mm Thick Q460 Grade TMCP Plate with High Toughness for Engineering Machinery

Based on low carbon and Cr-Mo with powerful carbide added,the 80mm thick Q460 grade plate for engineering machinery use was successfully trial-produced by TMCP process.Ultrafine grain and precipitated phase and bainite were fully taken advantage of to increase strength.By means of metallographic examination and inspection of mechanical properties,the results showed that the studied steel was composed of uniform ferrite and bainite,and had good mechanical properties including tensile property and low temperature impact toughness;A_KV under-60 ℃ was more than 180 J,and the impact fracture exhibited plastic deformation;SEM analysis showed that the area of dimple fracture was about 55%,and small inclusion in dimple was circular oxide.The result of TEM showed that high density dislocation existed in crystalline grain,and a large number of dispersed fine second-phase particles were separated out along dislocation line in the steel.