A Process Study On Strengthening And Toughening Of FH460 Steel

In recent years,with the development of ship for large tonnage,the demand of high strength hull structure steel is growing more and more and it demands higher quality and property of ship plate steel at same time,the proportion of high strength ship steel will be increased year by year.Because of the characteristics of high strength and toughness for FH460 strength ship steel,so it's an important part of ship plate and offshore platform steel.At present,the majority of high strength ship plate steel with small thickness produced by quenching and tempering process,however,with the development of thick walled direction for ship,the ship plate with conventional thickness has been unable to meet the rapid development of steel,so other production processes should be studied to produce hull structural steel with large thickness.In this paper,as the background of developing FH460 ship steel with large thickness,the different process and its influence to microstructure and property of FH460 hull steel through the design of the chemical composition and the application of TMCP technology are carried out by the laboratory study,and it provides a theoretical basis for the actual production process parameters.The main conclusions of this paper are given as follows:(1)The dynamic CCT curves of FH460 steel is measured by Gleeble3800 thermal simulation testing machine in the thermal simulation experiment.The influences of different cooling rate on the microstructure and property of FH460 ship plate are analyzed and the critical transition temperature of each phase under different composition is obtained.(2)The rolling experiment of the laboratory is studied based on the results of dynamic CCT curve measurement in the thermal simulation experiment.The rolling test on experimental steel with different thickness(40mm?50mm)and components by making different parameters of TMCP process,and the influence of composition and process on the microstructure and mechanical properties of the steel is analyzed by the test results of the performance and microstructure of rolled steel plate(3)Industrial test is carried out on FH460 with 80 mm thickness in the hot-rolled unit of AnSteel based on the results of thermal simulation and rolling experiments.According to the results of industrial trial manufacture,the FH460 steel with good strength and impact toughness can be produced by means of decreasing Mo content and adjusting process parameters of TMCP appropriately,and meet the standard of the FH460 ship plate steel.