Research And Application Of TMCP Of Ti Microalloyed Wide And Heavy Plate Q345 Steel

The thesis is combined with the project of "add the Ti element to improve the clemency board the first qualified rate of low alloy high strength structural steel" of Sha-steel,through thermal simulation experiment,hot rolling experiment in laboratory and industrial experiment,the structure property?the high temperature deformation behavior?precipitation behavior of TiC and effect of thermo-mechanical control process on microstructure and mechanical properties of high strength low alloy structural steels of different Ti content were investigated,the final process of industrial production was determined.Main studies are rendered as follows:(1)Taking the Q345 steel as the research object,the experiment process of five different Ti content had been designed,then been smelted and rolled in the laboratory,the tensile and impact properties of the experiment steel plate of rolled with different Ti content composition had been researched.(2)The double pass thermo-simulation compression experiment of 4#sample(containing 0.055%Ti)has been carried out by Gleeble-3800 thermal simulation machine,the stress-strain curve of the Ti experiment sheels were obtained by experimental equipment,the high temperature deformation behavior was researched by analyzing the stress-strain curve.Metallographic samples were taken in the middle of the sample to study the metallographic structure.It is concluded that the upper limit of the non-recrystallization temperature of the Ti-added test steel is about 880?,and the upper limit of the incomplete recrystallization temperature is about 920?.The thermal simulation experiment of the metamorphic austenite was carried out,taking samples in welding thermocouple,the TiC deposition of different deformation temperature was observed in the transmission electron microscope.It is concluded that deformation and heat preservation at around 850? is most beneficial for TiC precipitation.(3)Combined with the results of thermal simulation experiments,the hot rolling experiments for 3#components(containing Ti 0.034%)was carried out in laboratory,the effect of different rolling temperature on the microstructure and mechanical properties of steel plate was studied by comparing the rolling temperature.The final rolling temperature of 3-1#is 960? in complete recrystallization region,the final rolling temperature of 3-2#is 900? in part of rolling is in incomplete recrystallization region,The final rolling temperature of 3-3#is 840? in part of rolling is in non-recrystallization region.By analyzing the tensile and impact of the steel plate produced by the 3#component experimental steel under different finishing temperature processes,it is concluded that the final rolling temperature has less influence on the strength and elongation of the steel plate,but the impact on the impact toughness is obvious.(4)Through the analysis of laboratory research results,the main production process parameters in the later on-site production and debugging were determined to be that the Ti content of the smelting blank should be controlled within the range of 0.025-0.035%;to ensure the impact properties of steel plate,the final rolling temperature should be controlled under 880?.(5)Through 5 times steel rolling production debugging on-site,after the analysis of relevant data confirm,the final rolling process specifications for thickness of 30 mm or less Q345B finishing temperature should be controlled between 860-890?,the cooling process is air cooling;the thickness of 30-40mm Q345B of the final rolling temperature should be controlled between 86-880?,the cooling process is rapid water cooling:the finish cooling temperature should be controlled between 700-750?,the cooling water should be controlled between 800-1300L/s,the cooling process should use head and tail shielding.