Research On Repairing Process And Performance Of Q460 Steel By Arc Welding And Composite Laser Shock Forging

In response to the development of "carbon neutrality and carbon peaking",the country has gradually shifted energy extraction to offshore wind energy.The offshore wind power installation platform is one of the important tools for offshore wind energy exploitation,and its legs are an important structure to support the offshore wind power installation platform.However,the legs are often exposed to harsh environments such as wave impact and seawater corrosion,which can easily cause damage and corrosion to the legs.However,the replacement of the legs requires a lot of manpower,material resources and time costs.In order to save costs and improve work efficiency,repair technology is generally used to repair and remanufacture the failed parts.However,traditional repair techniques such as arc welding,laser cladding and brush plating often have some defects such as pores,cracks,and slag inclusions.Appropriate repair techniques are needed to make up for the defects.In this thesis,a new type of composite welding repair technology-arc welding composite laser shock forging technology is proposed.This technology uses the shock wave introduced by the pulsed laser to forge the welded joint,which can solve the defects such as pores and cracks in the welding seam,and can also improve the performance of the repaired welded joint,prolong the service life of the repaired parts,and improve the shipbuilding industry.It is of great significance to save costs and improve production efficiency in the shipbuilding industry.The test mainly uses Q460 low-alloy high-strength steel as the matrix,ER110S-G welding wire as the filler material,and uses arc welding composite laser shock forging technology for welding repair.The main research work and contents are as follows:（1）The Ansys finite element software was used to simulate and analyze the temperature field and stress field distribution law of arc welding composite laser shock forging technology,and to explore the feasibility of arc welding combined laser shock forging.The results show that the temperature field distribution in the welding process mainly changes with the movement of the heat source.It can be seen from the residual stress analysis that the residual tensile stress on the weld surface is reduced after arc welding composite laser shock forging technology,which proves that laser shock can introduce forging force on the weld surface.（2）The influence of different arc voltage,arc current,welding speed and laser shock frequency on the welding seam forming quality and welding seam size was explored by the control variable method,and the optimal process parameters were optimized.The experimental results show that: the arc voltage is too large or too small will affect the welding seam forming quality,and the welding seam width and penetration size both increase with the increase of the arc voltage;the increase of the arc current can effectively improve the welding seam The surface is formed,and the fusion width and penetration size of the weld increase;the change of the welding speed has a great influence on the quality of the weld formation,and the penetration width and penetration of the weld both decrease with the increase of the welding speed.;The laser shock frequency can improve the surface quality of the weld and reduce the generation of cracks and pores,but it has little effect on the penetration depth and width of the weld.The best process parameters can be obtained through exploration and research: the arc voltage is 24 V,the arc current is 160 A,the welding speed is 0.35m/min and the laser shock frequency is 10 Hz.The welding seam obtained by the optimal process parameters is of good quality,and the cross-section is free of any defects such as pores and cracks.（3）The microstructure,mechanical properties and electrochemical corrosion properties of welded joints under different laser shock frequencies were studied.The results show that with the increase of the laser shock frequency,the microstructure and grains of the weld zone of the welded joint are refined,the microhardness of the weld zone increases gradually,and the hardness of the heat-affected zone near the weld zone increases,but the change Not much.Due to the effect of laser shock,the tensile fracture position of the welded joint is transferred from the weld zone to the heat-affected zone,and the tensile strength of the welded joint increases with the increase of the laser shock frequency.With the increase of the laser shock frequency,the electrochemical polarization curve gradually moves to the lower right,the selfcorrosion potential increases,the corrosion current gradually decreases,and the pit area on the corrosion surface decreases,which indicates that the corrosion resistance of the welded joint is improved.promote.