热轧后中间退火对5059铝合金耐蚀性能的影响

Effect of Intermediate Annealing on the Corrosion Resistance of Hot-rolled 5059 Aluminum Alloy

为了研究中间退火对舰船用5059铝合金耐蚀性的影响,通过400℃/2 h中间退火和57%变形量的冷轧获得了不同5059铝合金板材,分别为热轧板、热轧退火板、直接冷轧板和退火冷轧板。分析了4种不同板材微观组织,并按照美国ASTM G67-2013标准分析了不同板材的耐蚀性。结果表明:400℃/2 h退火后,热轧板材内发生部分再结晶,耐蚀性提高,单位面积质量损失由热轧后的8.9 mg/cm 2降至3.1 mg/cm 2,L-S面的最大腐蚀深度由热轧试样的70μm降至6μm;热轧和400℃/2 h退火试样经57%变形量的冷轧变形后耐蚀性存在明显差异,单位面积质量损失分别为9.5 mg/cm 2和17.3 mg/cm 2,L-S面的最大腐蚀深度分别为45μm和65μm;热轧板经过400℃/2 h退火后L-T面和T-S面由热轧后的剥落腐蚀形貌转变为点蚀形貌,L-S面则由热轧后的沟壑状腐蚀形貌转变为点蚀形貌。

The 5059 aluminum alloy plates,such as hot-rolled plate,hot-rolled annealed plate,direct cold-rolled plate and cold-rolled annealed plate,were prepared with intermediate annealing and cold rolling to study the effect of intermediate annealing on the corrosion resistance of the alloy.The intergranular corrosion properties of different plates were analyzed according to U.S.ASTM G67-2013 standard.The results show that the partial recrystallization happens and the corrosion resistance of the plate is significantly improved after the annealing treatment of hot-rolled plate at 400℃for 2 h.With annealing at 400℃for 2 h,the corrosion weight loss of the hot-rolled plate decreases from 8.9 mg/cm 2 to 3.1 mg/cm 2,and the depth of corrosion channel on L-S cross-section decreases from 70μm to 6μm.The cold-rolled plates prepared with different states of the hot-rolled plates(with and without annealing)show quite different level of corrosion resistance.The corrosion weight losses of the cold-rolled plates with and without intermediate annealing are 17.3 mg/cm 2 and 9.5 mg/cm 2,and the depths of corrosion channel on L-S cross-section of the corresponding plates are 65μm and 45μm,respectively.The L-T and T-S cross-sections of hot-rolled plate present exfoliation corrosion morphology,and the L-T cross-section shows gully corrosion morphology.After annealing 400℃for 2 h,the corrosion morphologies of 3 cross-sections are all transformed into pitting morphology.