An Investigation On Alloy By Laser Microstructure And Properties Of Ni-based Cladding

Laser cladding process performance can be deposited at a lower price metal alloy substrate surface and basically no impact on the basic savings amount of precious metals materials, has a very high cost, the application is very extensive in the industry.Laser cladding process can be applied to smelting the High-performance alloy on the lower price metal alloy substrate surface without substantially impacting on the substrate, saving materials the amount of precious metals. Therefore, Laser cladding has very high economic benefits and is widely used in the industry.Nickel-based cladding materials, suitable for the parts requesting wear-resisting, heat resistant and heat resistant corrosion fatigue, are widely used. In this paper, nickel-based alloys and nickel-based alloys with WC powder particles was selected as the cladding materials. First, choosing nickel-based alloy as the cladding material for single-layer single-channel laser cladding process under different parameters conditions, this article studied the morphology characteristics of cladding layer, the affecting on organization and performance under different process parameters. Then, selected nickel-based alloys with different content of WC as cladding materials for laser lap cladding, and studied the microstructure and properties of the cladding layer of cladding material at different ratios. Some conclusions can be drawn as follows:1, Keep other process parameters same, increase scanning speed reduced the width of the single-channel monolayer laser cladding layer while increase the feed rate had little effect on the width of single-channel monolayer laser cladding layer, and the width increases as the laser output power increases; increase scanning speed reduced the height of the single-channel monolayer laser cladding layer while increase the feed rate or increasing the laser output power can increase the height of the single-channel monolayer laser cladding layer; increase the scanning speed or increase the feed rate can reduce the depth of molten pool of the single-channel single laser cladding, but increase the laser output power make the depth of the molten pool deeper.2, Dendrites are the major microstructure on the cross-section of single-channel monolayer laser cladding. The microstructure from the interface of the matrix and the laser cladding layer to the surface of the laser cladding layer are flat grain structure, cellular structure, columnar dendrites and steering dendrites. In the laser cladding process, the ratio between the temperature gradient G and solidification rate R, that G/R, has a very big impact on the microstructure of the cladding layer eventually formed. Maintain other process parameters in same, increase the scanning speed can decrease the ratio between G and R, thus refine the microstructure; when increase the feed rate, substrate temperature and melt cover material on specific energy per unit mass will decrease, so get the cladding microstructure refinement; The matrix temperature and the specific energy of cladding material on per unit mass tends to dip, which leads to the microstructure refinement in cladding layer; when the laser output power increases, the cooling rate of the cladding layer will slow down, and the specific energy of cladding material on per unit mass can be higher than that, and so that the cladding microstructure get coarsening; The micro hardness increases as the velocity of scan speed and the feed rate increase, but the micro hardness would reduce as the laser output power increases; The diluted cladding region and the heat affected zone decreases as the scanning speed and feed rate increases while increases as the laser output power increases.3, The quality of the thin wall formed by longitudinal lap of cladding layer is directly affected by the matching rate of cladding material on certain laser cladding process. Under the same cladding condition, the microstructure of cladding layer changes as the ratio of WC in cladding materials increase, from having more bone-like dendrite structure gradually to no obvious microstructure characteristics existing, and there are a lot of carbide not evenly distributed in cladding layer. The main phase has CCrFeNi, SiCrFeNi, CrFeNiW and WC in four different regions. When the amount of cladding material WC reaches 50%, the microstructure of the first layer is more refined than the microstructure the second layer in multi-layer laser lap cladding. The micro hardness will increase and the wear resistance of cladding will be better as the proportion of WC increases in cladding materials.