| IN690 is an austenitic nickel-based wrought super-alloy, which has high strength, good metallurgical stability, good weldability and excellent processing characteristics, more importantly, it has excellent ability of resistance to intergranular stress corrosion.It has become an ideal material for the heat exchanger tubes of steam generator.IN690 alloy tubing extrusion process has been studied through experiments and numerical simulation,and it provides a theoretical basis for the actual production of pipe extrusion. The main results and conclusions are as follows:(1)The true stress-strain curve was obtained by isothermal constant strain rate compression experiment, and the thermal deformation behavior of IN690 alloy was studied systematically. The constitutive relation model of IN690 alloy based on the hot compression experimental results was established.(2)The lubrication behavior of IN690 alloy extrusion process was simulated.The squeeze pressure changes under different angle of the glass mat and the impact on the extrusion process of glass mat were studied. The reasonable dip of glass mat and the function of glass mat in the extrusion process were obtained.(3)Multi-field coupling of IN690 superalloy tubing extrusion process based on finite element software was simulated. The laws of temperature field, stress field and extrusion pressure variation was studied under different process parameters. The influence rules of different process parameters on the tube extrusion process was obtained.(4)A subroutine with microstructure evolution model had been compiled using Fortran language, which can predict the microstructure evolution of IN690 alloy. The influence of different parameters on microstructure evolution in the pipe extrusion forming process had been analyzed. Verify the accuracy of numerical simulation, and obtained the reasonable parameters of pipe extrusion process. |
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