Design Of Laser Welding Tools And Study On Welding Process Of Dual-phase Steel

As a kind of high efficiency and high quality welding technology,laser welding has many advantages,such as fast welding speed,narrow heat-affected zone and small welding deformation,which has been developed for more than ten years.In this paper,with the help of a large power laser welding platform equipment,two-phase steel as the research object,the following research is carried out:1.Aiming at the test of nuclear power project,the design of laser welding fixture is carried out,The tooling model is established by using SolidWorks 3D and Auto CAD 2D software,With the help of ANSYS Workbench,the designed welding tool platform is checked by finite element method.The stress value and deformation value of the pipe welding equipment are analyzed,and the following points are obtained:(1)In the process of turning,the maximum equivalent stress occurs on the pipe support rod and the maximum deformation occurs on the support frame.With the increase of the rotation angle,the maximum equivalent stress and the maximum deformation change gradually,and show a sine law.(2)The pipe welding tooling equipment is made of low carbon steel Q235.The maximum equivalent stress during the pipe welding equipment installation process is 155 MPa,and the safety factor is 235/155=1.52.It is known that the equipment meets the design requirements.(3)The deformation of the pipeline has little effect on the focal depth of the laser hot wire welding.There is no need to compensate for the laser hot wire welding and the pipe welding tooling equipment has been basically completed.It is now ready for use in laboratory pipe welding.2.Use welding fixture designed,The welding experiment of 2205 duplex stainless steel,which is widely used in nuclear construction,is carried out.The welding process parameters are designed by orthogonal test and control single variable method.The forming rules of laser profiling,laser power,welding speed and other welding process parameters on the macroscopic morphology of 3mm thick 2205 duplex steel welds were investigated.It is obtained that when the defocus amount is-5 mm,the focus can be applied to the inside of the weldment,thereby obtaining a larger deep melt;Through comparison and analysis,the welding seam has different heat input quantity under each welding process parameter,and can get different weld depth-width ratio,so that different weld depth-width ratio can be obtained.When the defocus is-5mm,the laser power is 2kW,the welding speed 0.75m/min and defocus is-5mm,the laser power is 1.5kW,and the macro-forming is good when the welding speed is 0.5m/min.Finally,the forming law and mechanical properties of Austenite and Ferrite in dual-phase steel were analyzed by scanning electron microscope(SEM)and PWS-E100 universal testing machine.It is obtained that when the laser power increases(or the welding speed slows down),the thermal input of the weld increases further,the cooling rate of the weld slows down,and the diffusion of elements and the structural transformation of the crystal are more mature.The Austenite gradually thickens from the fine strip,and the microstructure of the Ferrite also grows up gradually,that is,it changes from the slender columnar crystal to the large equiaxed crystal.The ferrite isaxic crystal can precipitate more Austenite structure and show different mechanical properties,It lays an effective foundation for the same kind of laser welding experiment.