Study On Key Process Parameters Of 2507 Super Duplex Stainless Steel Rebar

Under the policy of building a maritime power,the marine engineering structure and the seawater corrosion resistance of offshore construction facilities are very important,especially the characteristics of high humidity,high chloride ion concentration and high ultraviolet ray in the South China Sea environment.The corrosion of marine engineering structures is more serious.In order to ensure the safety and life requirements of buildings,it is necessary to develop high-strength and economical duplex stainless steel bars suitable for use in marine construction environments.In this paper,the 2507 duplex stainless steel produced by the laboratory is used to control the microstructure by solid solution process,and the excellent comprehensive mechanical properties and corrosion resistance are obtained.Through the study of hot working behavior,the deformation activation energy and hot deformation equation are obtained,the processing maps under different strains are established,and the optimum process parameters for hot deformation of the alloy are determined.The microstructures were controlled by solid solution process,and excellent comprehensive mechanical properties and corrosion resistance were obtained.The CCT curves at different solution temperatures and the phase contents at different temperatures under equilibrium were calculated by using JMatPro and Thermo-Calc thermodynamic software.When the solid solution temperature is 1180?,the ratio of?:?is close to 1:1,the precipitation temperature of?phase is about 1040?,and the temperature sensitivity coefficient of 2507 super duplex stainless steel is very high.According to the results of computer simulation calculation,solid solution treatment experiments were carried out at different temperatures.The results show that brittle phase precipitates in the microstructure of hot rolled stage or 1050?¹100?interval.The temperature range of the brittle phase without precipitation is 1150?¹200?,and the percentage of ferrite area increases with the increase of solid solution temperature.The microstructure of the two phases is homogeneous at 1180?.The ratio of the duplex phase is the closest to 1:1.The mechanical properties of 2507 duplex stainless steels with different solid solution states were tested.The results showed that tensile strength Rm was about 824MPa in the range of 1150?¹200?,yield stress Rp_0.2 was about 550 MPa,the elongation and section shrinkage at 1180?reached their maximum values of 39.5%and 70%,respectively.The maximum impact energy at 1150?was 350J,and the maximum impact energy was between 1150?and 1180?.It has excellent mechanical properties.The chloride ion corrosion resistance of 2507 duplex stainless steel with different solid solution states was tested.The results of polarization curves and AC impedance spectroscopy showed that the corrosion resistance of the tested steel increased first and then decreased in the range of 1050?¹200?.The corrosion resistance of the tested steel was the best in the range of 1150?¹180?.The deformation activation energy of 2507 duplex stainless steel is 450.34KJ/mol,n=3.7417,and the strain rate sensitive factor m and energy consumption efficiency at 0.7strain,different deformation temperature and strain rate are obtained.The hot working diagram of 2507 duplex stainless steel is established,and the optimum true strain is 0.7.The optimum processing parameters are 1050?¹200?,and the strain rate is 0.1s^-11s^-1.