Numerical Simulation For Butt Welding And Analysis For Welding Process Of TA2-Q345 Clad Plate

Due to the high strength of steel and good corrosion resistance of titanium,TA2-Q345 clad plate is widely used in the pressure vessel.Pressure vessels generally work at high temperature,pressure,and even in the environment with corrosive media.At the same time,the welding residual stress is inevitable in the manufacturing process of the pressure vessel,and welding residual stress directly shorten the service life of pressure vessel at high temperature,pressure and corrosive media.Based on the thermal elastic plastic theory,the ANSYS finite element software was utilized to study temperature field and stress field of TA2-Q345 clad plate under different welding parameters,acquiring the residual stress distribution in weldments.Meanwhile,the microstructure and mechanical properties of TA2-Q345 clad plate under different welding parameters were studied.The finite element calculation results show that the similar temperature distribution can be observed by welding the back welding of cover-plate using self-fluxing and filler wire.However,the residual stress value is lower using self-fluxing welding cover-plate.And more,the residual stress increases with increase of welding line energy.Microscopic observation shows that the microstructure of TA2-Q345 clad plate is fibrous under the low welding line energy at the interface.With increase of welding line energy,the fibrous disappeared at the interface.The grains size increases with increase of welding line energy.Under the low welding line energy,the welding seam of the sub-plate is composed of coarse serrate ?-phase and lath ?-phase,under the high welding line energy,the welding seam of the sub-plate is mainly composed of ?-Ti.The grains grow and become equiaxed under the high welding line energy.Mechanical properties test results show that the microhardness at the interface is higher than that at the both sides,the microhardness increases with increase of welding line energy.The tensile strength of the clad plate decreases with increase of welding line energy,meanwhile,the shear strength decreases.The shear strength is the lowest at the interface of the clad plate(corresponding to the vicinity of the sub-plate weld-line and the cover-plate weld-line).The results of microstructure and mechanical properties show that the method of self-fluxing welding cover-plate is an appropriate process,in which the welding line energy is 16.26kJ·cm-1 for subplate welding,18.08kJ·cm-1 for cover-plate backing welding,and 17.87kJ·cm-1 for cover-plate capping welding.