Study On Preparation Process And High Temperature Oxidation Behavior Of Ni Based Alloy Coating By Laser Cladding

Due to high thermal strength and hardness,high wear resistance and toughness,and good thermal fatigue properties,H13 steel is widely used as hot work die steel.As is well known,the failure of the die begins at the surface firstly.Therefore,improving the surface microstructure and the performance can effectively improve the service life of the mold.In this study,the high temperature resistance of H13 steel was improved by Laser Cladding Ni based alloy coating.Studying the influence of different power density,feeding rate and scanning rate on the appearance quality and tissue growth of Ni based alloy coating.The high temperature oxidation treatment is done to samples for 48 hours at 400?,500?,600? and 700?.Observing the thickness and composition of the oxide layer to study the high temperature oxidation performance of them.Observing the morphology and microstructure of coating by scanning electron microscope,analysing chemical composition,high temperature oxidation behavior,phase composition and crystal structure and of coating by EDS and XRD,testing the hardness of oxidized samples by Vickers.The results show that the microstructure of Laser Cladding Ni based alloy coating is directional columnar dendritic structure.With the increase of laser power,the thickness and the width of the Ni-based coating are increased,and the grain size increases.When the other parameters are constant,he density of the cladding layer increases with the increase of the feeding rate,that is,the hole decreases.When the feed rate and the scan rate are increased,the nickel based alloy coating is obviously cracked.The nickel oxide to 400? after 48 hours of high temperature oxidation of Ni base alloy coating,and chromium oxide.With the increase of the oxidation temperature,he XRD diffraction peak of the oxide is obviously enhanced,and the content of the oxide is increased.When the temperature reached 700?,the oxide peak became stronger than the nickel based alloy coating.The oxide thickness of the sample increased with the increase of the oxidation temperature.After oxidation at 700?,the oxide thickness increased obviously.At the same time,there is a clear boundary between the oxide layer and the matrix,and the combination of them is not good.The structure of porous structure is observed in the matrix near the oxide layer,which can be the porous structure of the oxygen atom through the oxide layer to the internal diffusion.Laser cladding Ni based alloy coating can improve the oxidation resistance of H1 3 steel significantly.