TIG cladding in-situ nano vanadium carbide reinforced Fe-based ultra-fine grain layers under water cooling condition

In-situ vanadium carbides reinforced Fe-based TIG cladding layers were obtained under air cooling and water cooling conditions. The effects of the different cooling conditions on carbides size, grain size and properties of cladding layers were comparatively studied. The results showed that in-situ nano vanadium carbide reinforced Fe-based ultra-fine grain layers could be obtained under the water cooling condition. This cladding layer showed a narrower heat affected zone and a lower dilution rate. The average grain size of the cladding layer is 1.90 mu m. Carbide has two morphologies, one consists of submicro/nano particles with an average particle size of 0.15 mu m, and the other consists of rod-like particles with an average diameter of 0.09 mu m. High resolution transmission electron microscope results indicated that the nanoscale carbides were V6C5 and VC. The hardness of the water cooling cladding layer was significantly increased by 375 HV0.2 to 905 HV0.2. The corrosion rate indicated that the corrosion resistance was approximately 5.6 times greater as compared with the air cooling cladding layer. The passive film formed on the air cooling cladding layer were Fe3O4 and V2O5, and that formed on the water cooling cladding layer was Fe2O3 and Fe3O4.