Papers by Author: Hong Fang Liu

Abstract: Using weight-loss method combined with metallographic to analysis the effect of annealing temperature (600°C, 640°C, 680°C) on the corrosion resistance of cold rolled strip of complex brass HAl72-2.5Al-1.0Ni alloy. Corrosive solutions for testing the corrosion velocity were 3.5% of the neutral sodium chloride solution, artificial acid rain (3.5% NaCl+H₂SO₄ solution) and artificial sweat solution. The research results show that the corrosion of cold rolled strip occurs easily because grains stretched along the direction of deformation and the existence of residual stress. The maximum corrosion depth of cold-rolled strip is 94.8μm. Annealing treatment can effectively reduce the corrosion depth of alloy. Corrosion resistance of alloy rises with the increase of annealing temperature, because the recrystallization degree of alloy goes on more sufficient. The corrosion depth of samples annealed at 600°C and 680°C drops from 64.45μm to 56.32μm respectively. Aluminum content in the alloy also affects the corrosion resistance of the alloy, because oxygen oxidizes aluminum to density Al₂O₃ film which prevents the further corrosion of the alloy. The corrosion velocity of samples in the solution of artificial acid rain is fastest and lowest in artificial perspiration solution.

Abstract: Studying effects of Ni content (0.6%, 0.8% and 1.0%) on structure and properties of aluminum brass (Cu-22.7Zn-3.0Al) as-cast ingot, cold-rolled and annealed sheet. The results show that: Ni can restrain the precipitation of β phase, and increase percentage of α phase during casting process. The proportion of α phase of ingot as-cast grows up with the increase of Ni content in the alloy. α phase refines gradually and shape changes to needle-like and distributes more uniform with the increase of Ni. The average grain size of α phase of ingot as-cast is 33.57μm, 31.78μm and 28.32μm respectively, and the percentage of α phase as-cast is 69.73%, 75.18% and 78.91% corresponding to 0.6%, 0.8% and 1.0% Ni respectively in the alloy. The tensile strength and hardness enhance and elongation drops with the increase of Ni content. The hardness, tensile strength and elongation is 238.7HV, 784.9MPa and 3.7% respectively for 0.2mm thickness cold-rolled sheet with 1.0% Ni in the alloy. The sheet from 1.0mm to 0.2mm thickness undergoes deformation and heat-treatment process. The hardness and tensile strength of cold-rolled strip of 0.2mm thickness are 205HV and 691.16MPa that increase 13.25% and 16.45% than cold-rolled sheet of 1.0mm thickness.