Reasearches Of Laser Cladding Ant-wear Layers On20Steel Surface

Laser cladding use high energy laser beam to melt coating material and a thin layer base metal to form a kind of good metallurgical bonding surface coating. It was one of new techniques in the modern surface technique system that infinite development future and characteristic. Laser cladding layer has good wear and corrosion resistance properties and the technique is good for repairing and enhancing of work pieces. Laser cladding have widely use in industry of aerospace, automobile, metallurgy, petroleum, chemical industry and etc.20#steel has good structural strength, low-cost and has been widely applied in table rollers. However, seriously cracks and abrasive-wearing damages were found in20#steel made table rollerss. In order to decrease its crack tends and to improve its mechanical properties, Ni60laser cladding layer, Ni60+Y2O3laser cladding layer and Ni60laser cladding-remelting layer were made on surface of20#steel by Nd:YAG LASER. And morphologie character, corrosion resistance and abrasion resistant properties of these different kinds of cladding layers and influence of Y2O3to Ni60laser cladding layer were investigated separately.The result shows that Ni60laser cladding layer and Ni60+Y2O3laser cladding layer has good surface quality. Cross section rise with interaction time and energy density increasing. And there was crack and role in Ni60cladding layer and Ni60+Y2O3laser cladding layer. Adding laser remelting step could reduce these defects. The matrix of the Ni60laser cladding layer and Ni60laser cladding-remelting layer is (Fe, Ni) solid solution. Ni60laser cladding layer was strengthened by hard precipitated phases such as Cr23C6、Fe3B、CrB etc. Micro hardness of Ni60cladding layer and Ni60+Y2O3laser cladding layer were about4times of the20#steel matrix (206HV) and Micro hardness of Ni60cladding-remelting layer was about4times of the20#steel.High temperature abrasive-wearing resistance of Ni60laser cladding layer was3times of20#steel. The improvement in high temperature abrasive-wearing resistance of the layer was due to the metallurgical combination;(Fe, Ni) solid-solution enhancement effect and strengthen effects of borides and boron-carbides precipitated phases. High temperature abrasive-wearing resistance of Ni60+Y2O3laser cladding layer was1/4times of20#steel. The improvement in high temperature abrasive-wearing resistance of the layer was due to the metallurgical combination;(Fe, Ni) solid-solution enhancement effect and strengthen effects of borides and boron-carbides precipitated phases and Y2O3particles. High temperature abrasive-wearing resistance of laser cladding layer was4times of20#steel specimen. The improvement in high temperature abrasive-wearing resistance of the layer was due to the metallurgical combination; strengthen effects of borides and boron-carbides precipitated phases and less harmful cracks.After high temperature abrasion test, the three kinds of laser cladding (or laser cladding-remelting) layers were all shown plastic deformation scratch morphologie. Ni60cladding-remelting layer and Ni60+Y2O3laser cladding layer shown more flat wear surface and less wearing furrows and have higher high temperature abrasion resistant properties.