Research On Deformation Control Of Laser Cladding Process Of Thin Plate

Laser cladding is a surface modification technology that uses a high energy density laser beam to melt the substrate and the cladding powder to form a new metallurgical bonding layer on the substrate surface.Laser cladding technology can repair complex parts and improve the physical properties of the parts,extending the service life of the parts.Laser cladding is a periodic cycle process of rapid heating,melting and cooling and solidification.Uneven local heating during the cladding process will cause a large temperature gradient in the cladding part,and resulting in deformation of the cladding part,and the deformation of thin plate parts during the laser cladding process is particularly obvious.This paper has conducted technological research on the deformation control of the laser cladding of thin plate.We studied the method of laser cladding scanning path control of thin plate deformation.We use the displacement sensors and three-coordinate measuring instruments to studied the dynamic deformation measurement analysis and the overall deformation measurement analysis of thin plate,and the thermal expansion and contraction deformation law and the overall deformation trend during the cladding process of thin plate can be obtained.Furthermore,the influence of different scanning methods on deformation was studied.The results show that the unidirectional longitudinal scanning with unilateral constraint and the reciprocating scanning with bilateral constraint can effectively control the deformation of thin plate.The method of using forced cooling to control the deformation of thin plate during the laser cladding process was studied.After studying the deformation law of thin plate under the conditions of no water cooling and water cooling,it was found that the forced cooling method can effectively control the deformation of thin plate during the laser cladding process,and the cooling field can significantly reduce the temperature field accumulation of thin plate and the molten pool size.Through measuring residual stress by the small hole release method found that the longitudinal residual stress in the parallel cladding direction and the residual stress in the vertical cladding direction with the forced cooling were greater than those without the cooling method.The cladding position and the deformation law of thin plate during multi-layer cladding were studied.The deformation trend is similar when cladding at the centerline and edge of thin plate.The thin plate will gradually change from convex deformation to concave deformation,and adopting the method close to the restraining end can effectively control the deformation of thin plate,and the residual stress at the same point is symmetrically distributed.During multi-layer cladding,it was found that the use of intersection scanning can effectively control the deformation of thin plate and effectively reduce the stress concentration of thin plate.The three scanning paths with unilateral constraints were numerically simulated using ANSYS for the temperature field and stress field,respectively,and the simulation results were consistent with the experimentally measured values.After pre-heating the thin plate that unidirectional scan,it was found that when within a certain number of passes,the application of preheating temperature can effectively control the deformation of thin plate and can effectively reduce the residual stress inside thin plate.