Research Of Technology And Properties Of Laser Cladding On Ni/Wc-La₂O₃ Surface Of T10 Steel

Laser cladding is an advanced materials surface modification technology,in which the pre-selected cladding materials can be placed on the substrate by difference way ,by laser irradiating, the cladding materials are fused onto the substrates'surface .Owing to the peculiar characteristics of laser, laser cladding provides good metallurgical combine, minimal dilution and low distortion of the materials, and the accompanying rapid solidification effects produce refine and novel microstructures with improved properties. In recent years, laser cladding develops very rapidly and shows a brilliant application future in wilds fields of industry.The main subjects of the paper is the T10 steel, and emphasis on researching the techniques of laser cladding Ni alloy on the T10 steel and the microstructure, performance, preventing the crack and the overlapping of cladding layers, and studied the capability and microstructure of Ni alloy with WC-La2O3 and Mo laser layers .The experiment result shows that there are three layers: the coating region, bonded zone and heat affected zone. In the right laser cladding parameter, we can get well union resistance cladding layer. The microstructure of cladding layer is composed by rod or grainy cellular crystals, because of laser speediness calefaction and cooling. In the cladding process, the speed everywhere of calefaction and cooling is different, so the distributing of hardness is asymmetry, it can be up to 925.6 HV0.1 in the secondary surface, the wearable properties also is highest.After adding the30%WC, the hardness of laser layer has little changing, but the wearable properties had a very enhancing, increasing a little sensitivity of laser layer. Compared to have not adding the WC, Cracks appeared likely have increased by 10%.After adding the 2.5%Mo, the coating is mainly made up of pseudo eutectics. The cracking sensitivity is improved at the expense of a little decrease in hardness, but the wear resistance dose not reduced. Mo has well distribution that fines the microstructures and reduce phases with lower melting points is reduced. On Mo is benefit to the fine of grain sizes and uniform distribution of microstructure.After adding the 1.0% La2O3, the coating is mainly made up of the dendrite. It played a role of the thinning dendrite in the laser cladding layer; In the same situation of laser power (2.5KW), with increasing of the scan rate (from 4mm/s to 6mm/s), the dendrite refine more apparently; Adding the REE La2O3, The average hardness raises about 150HV0.1 than not, between the 1.0% and the 1.5% La2O3 on the Multi-channel cladding, the former has a better wear resistance.The influence of laser power, scanning speed and off-focus to the cladding layer's hardness, surface wearable properties and microstructure were studied by using SEM, micro- hardness testing techniques, wearable properties testing and the orthogonal experiment analysis and so on. The result shows that the micro-hardness of the cladding layer is augment firstly and the then diminishing, the wearable properties of material also becomes well. This is designed by the microstructure becoming small. As the scanning speed becoming augment, the cladding layer's hardness and wearable properties have the same changing process.The paper selects laser power, scanning speed and off-focus as the influences to cladding layer, and chooses the right levels to make the orthogonal experiment. We get the laser cladding parameter adapt to produce actually in the hardening and surface wearable properties.