Experimental study on laser cladding WC/Ni powder to repair the cutting edge of cold working die

The work aims to study the influence of substrate surface inclination angle on the quality of cladding layer prepared by laser cladding to repair the edge of punch of cold punching die and find out the best process method for repairing the edge of punch and then verify the feasibility of laser cladding technology to repair cold punching die by numerical simulation analysis and practical processing of blanking process. WC/Ni cladding layers were prepared on Cr12MoV substrate surface with different inclination angles by two cladding methods, respectively perpendicular to the ground and the substrate surface. Through the analysis on section morphology, change of bonding quality and hardness of the cladding layer, the best repairing process was selected. The influence of the change of the substrate surface inclination angle on the microstructure and phase composition of the cladding layer was analyzed by XRD, SEM and EDS. According to the average hardness of the cladding layer and the measured data of the processed plate, the numerical analysis model was established. The wear accumulation method was used to solve the numerical model, and it was concluded that the repairing punch was used in the actual blanking process after meeting the expected service life, which verified the feasibility of laser repairing the cold working die and the reliability of the numerical analysis model. The cladding parameters were laser power of 1.2 kW, scanning speed of 2 mm/s, powder feeding voltage of 8 V and defocusing amount of 12 mm. When the inclination angle of the substrate surface to the ground was not more than 50° and the included angle with the laser beam was not more than 35°, the quality of the cladding layer was high. When the substrate surface was inclined, the peak value of the cladding layer was always in the center of the cladding layer, and the maximum depth of the molten pool moved to the side near the laser head. Two laser cladding methods were used, respectively perpendicular to the ground and the substrate surface. The cladding layer was made up of γ-Ni(Fe), Fe6W6C, Fe2B, WC, W2C, Cr7C3, W2B and other hard phases and complex gap compounds. The change of the inclination angle of the substrate only affected the refinement of the structure and the mass fraction distribution of the elements. Using laser cladding technology and appropriate repair technology can not only effectively repair the cold working die due to wear failure, but also play a role in local modification. The carbide and other hard phases formed in the cladding process play an important role in improving the hardness of the repaired area. The average service life of the repaired punch is 5283 times/piece, which is basically consistent with the simulation results of the finite element life prediction of 5600 times/piece, further verifying the accuracy of the numerical analysis model. © 2020, Chongqing Wujiu Periodicals Press. All rights reserved.