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对比研究一种新型三级时效制度(T76+T6)和常规回归再时效制度(RRA T77)对7150铝合金型材耐腐蚀性能的影响。选取三种腐蚀溶液(3.5%Na Cl;10 mmol/LNaCl+0.1 mol/L Na_2SO_4;4 mol/LNa Cl+0.5 mol/L KNO_3+0.1mol/L HNO_3),分别对7150铝合金型材进行开路电位、循环极化曲线以及电化学阻抗谱的表征。讨论自腐蚀电位、点蚀电位、点蚀转换电位以及电位差值等参数对铝合金腐蚀表征的适用性与局限性。电化学与扫描电镜(SEM)结果表明,相比于传统RRA T77制度,T76+T6时效制度处理的铝合金在没有强度损失的前提下,具备更好的耐点蚀、耐晶间腐蚀以及耐剥落腐蚀的能力。这是由于该新型三级时效制度处理的铝合金的晶界析出相进一步粗化和断续分布所致。
The effects of a new three-stage aging system (T76 + T6) and RRA T77 on the corrosion resistance of 7150 aluminum alloy profiles were compared. Three kinds of corrosion solutions (3.5% NaCl, 10 mmol / L NaCl and 0.1 mol / L Na_2SO_4, 4 mol / L Na Cl + 0.5 mol / L KNO_3 and 0.1 mol / L HNO_3) , Cyclic polarization curves and characterization of electrochemical impedance spectroscopy. This paper discusses the applicability and limitations of corrosion resistance, pitting potential, pitting conversion potential and potential difference on corrosion characterization of aluminum alloy. Electrochemical and scanning electron microscopy (SEM) results show that compared with the conventional RRA T77 system, the T76 + T6 aging treatment system has better resistance to pitting, intergranular corrosion and resistance to corrosion without strength loss Peeling off corrosion ability. This is due to further coarsening and intermittent distribution of the grain boundary precipitates of the aluminum alloy treated by the new three-stage aging system.