Corrosion and cavitation erosion resistance enhancement of cast Ni–Al bronze by laser surface melting
Q.N. Song1,2, Y. Tong2, H.L. Li2, H.N. Zhang2, N. Xu2, G.Y. Zhang2, Y.F. Bao2, W. Liu3, Z.G. Liu3, Y.X. Qiao3
1 Engineering Research Center of Dredging Technology of Ministry of Education, Hohai University, Changzhou 213022, Jiangsu, China; 2 College of Mechanical and Electrical Engineering, Hohai University, Changzhou 213022, Jiangsu, China; 3 College of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China
Corrosion and cavitation erosion resistance enhancement of cast Ni–Al bronze by laser surface melting
Q.N. Song1,2, Y. Tong2, H.L. Li2, H.N. Zhang2, N. Xu2, G.Y. Zhang2, Y.F. Bao2, W. Liu3, Z.G. Liu3, Y.X. Qiao3
1 Engineering Research Center of Dredging Technology of Ministry of Education, Hohai University, Changzhou 213022, Jiangsu, China; 2 College of Mechanical and Electrical Engineering, Hohai University, Changzhou 213022, Jiangsu, China; 3 College of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, Jiangsu, China
摘要 Laser surface melting (LSM) was applied on a cast Ni–Al bronze (NAB), which was a crucial material for marine ship propellers. A 720 μm-thick LSM layer with fine equiaxed and dendritic microstructures was obtained. After immersion for 30 days, the corrosion rate of cast NAB was reduced by 25% after LSM. Preferential corrosion occurred and deep corrosion pits appeared at a+kIII microstructure for the cast NAB. LSM NAB underwent general corrosion, and a much more protective film formed on the surface because of the homogenized microstructure. The mass loss of the cast NAB was approximately 2.1 times larger than that of LSM NAB after cavitation erosion (CE) in 3.5 wt.% NaCl solution for 5 h. For the two materials, the mechanical impact effect was dominantly responsible for CE damage. Therefore, the improved hardness and homogenized microstructure contributed to the improved CE resistance of LSM NAB. CE destructed the film, shifted the open circuit potential toward a more negative value, and raised the current density by an order of magnitude. Corrosion at the cast eutectoid microstructure and the dendrites of LSM NAB facilitates the degradation under the cavitation attack. CE-corrosion synergy was largely caused by corrosion-enhanced-CE.
Abstract：Laser surface melting (LSM) was applied on a cast Ni–Al bronze (NAB), which was a crucial material for marine ship propellers. A 720 μm-thick LSM layer with fine equiaxed and dendritic microstructures was obtained. After immersion for 30 days, the corrosion rate of cast NAB was reduced by 25% after LSM. Preferential corrosion occurred and deep corrosion pits appeared at a+kIII microstructure for the cast NAB. LSM NAB underwent general corrosion, and a much more protective film formed on the surface because of the homogenized microstructure. The mass loss of the cast NAB was approximately 2.1 times larger than that of LSM NAB after cavitation erosion (CE) in 3.5 wt.% NaCl solution for 5 h. For the two materials, the mechanical impact effect was dominantly responsible for CE damage. Therefore, the improved hardness and homogenized microstructure contributed to the improved CE resistance of LSM NAB. CE destructed the film, shifted the open circuit potential toward a more negative value, and raised the current density by an order of magnitude. Corrosion at the cast eutectoid microstructure and the dendrites of LSM NAB facilitates the degradation under the cavitation attack. CE-corrosion synergy was largely caused by corrosion-enhanced-CE.
Q.N. Song,Y. Tong,H.L. Li, et al. Corrosion and cavitation erosion resistance enhancement of cast Ni–Al bronze by laser surface melting[J]. Journal of Iron and Steel Research International, 2022, 29(2): 359-369.
2022, Vol. 29 
