| Laser cladding technology has good prospects for development in the field of surface treatment. The parts surface hardness, wear resistance and corrosion can be enhanced, the surface machining performance can be improved, and the failure parts due to wear can be repaired, prolong its service life, by selecting the cladding alloys. Cold stamping die easy to wear failure, due to its special working environment (high pressure and high friction, large area, etc.). The repair research that the application on the failure of cold stamping die using laser cladding technology was conducted in this topic, In order to improve the service life of cold stamping die, save resources, increase production efficiency.Different alloy powder were adopted for laser cladding repairing Cr12MoV cold stamping die steel in this subject. Cladding layer’s microstructure, element distribution, microhardness and wear resistance were tested by means of optical microscopy (OM), scanning electron microscope (SEM), energy spectrum analysis (EDS), microhardness meter and MM-200 wear testing machine. Microstructures and properties of cladding layer of cobalt base with WC reinforced phase composite powder were analyzed.The iron base、nickel base、cobalt base alloy powder can realize Cr12MoV cold stamping die cladding, employ the laser cladding process. Cladding layer structure is compact, no defects such as porosity, crack, and the base material has good metallurgical bonding. For iron and cobalt base alloy powder Cladding layer is mainly network eutectic organization and dense solid solution be surrounded. Nickel base alloy powder cladding layer is mainly fine dendrite and plume strip. By laser heat effect, Cr12MoV die steel surface divided into transition zone and hardened area. Transition region organization is bulky, in the condition of half melting composition segregation is serious, is the softening area in repaired surface. For hardened zone, organizational refinement, hardness increase much. Under different process parameters of laser cladding, the organization and performance have much change. relative to the laser power, Cladding rate effect on the microstructure and properties of cladding layer is more significant, with the increase of cladding rate, retention time became shorter, the faster the cooling, the organization of the cladding layer is small density.This topic also found that WC has a significant effect to cladding layer properties such as microstructure、hardness and wear resistance, by composite powder laser cladding experiments which adding different proportion WC reinforced phase. The mixture of the WC with Ni60 is poor, after laser cladding there is more unfused WC hard phase, which improved the wear ability of cladding layer. For cobalt base alloy powder, with the increase of WC reinforced phase ratio, the cladding layer hardness, wear resistance is higher and higher, state that cobalt base alloy powder with WC compatibility is very good. The wear resistance of cladding layer is base material of 2 ～6 times, especially abrasion resistance of Co06+20% WC alloy powder cladding layer completely reached the use requirements of the mold.Considering the demand of cold stamping die (high hardness, high wear resistance and certain toughness) and the subject test results, the best laser cladding repairing process for Cr12MoV die steel as follow:FeNi26 or Fe308 alloy powder is used for render cladding, Co06+20% WC alloy powder is used for laser repair; Middle cladding laser power is 3.6 kW, cladding speed is 3 mm/s; Cover surface laser power is 3.8 kW, cladding speed is 4 mm/s.Test result not only provides the technical support for Crl2MoV cold stamping die repair, also provides certain theoretical guidance for the laser cladding repairing of precision grinding tool, cold forging die, stamping dies, hot forging die and other easy to wear and tear parts. It has important application value and theoretical significance to expand the application of laser cladding technology in industrial production. |
PDF Full Text Request