EFFECT OF FLAME SPRAYING WELDING ON FATIGUE LIFE OF CARBON STEEL

The effects of coating Ni60 on the surface of fatigue specimens of tempered, normalized or rolled C45 steel by flame spraying and remelting on the fatigue life in air and on the corrosion fatigue life in 3.5% NaCl solution have been studied. The results show that:Ni60 coating will reduce the fatigue limit in air about 7% for tempered matrix and increase about 145% for normalized and rolled matrixes, but increase the corrosion fatigue strength of 10⁷ lifetimes over 30% for all matrixes. By fractographic analysis the process of fatigue fracture of thermally coated specimens and the corrosion fatigue behaviour of surface coating were studied. It is indicated that the microstructure and strength of the coating and bonding have their direct effects on the fatigue crack initiation and propagation.