7050超高强铝合金蠕变时效成形行为与性能研究

Study on Creep Age Forming Behavior and Properties of 7050 Ultra-high Strength Aluminum Alloy

对7050超高强铝合金进行蠕变时效处理,采用维氏硬度、晶间腐蚀和剥落腐蚀等试验对其力学性能与腐蚀行为进行研究,采用光学显微镜和透射电子显微镜对微观组织进行观察,研究蠕变时效对合金微观组织与性能的影响。结果表明:合金的稳态蠕变速率随温度的升高和应力的增大而逐渐升高,时效温度是影响合金蠕变速率和抗腐蚀性能的主要因素。7050超高强铝合金的稳态蠕变速率与蠕变应力和蠕变温度的关系可以表示为:ε=e(12.226)σ(1.66)exp(-120 536/RT)。蠕变时效处理后,合金的维氏硬度、抗晶间腐蚀和抗剥落腐蚀性能均得到提高。合金在120℃和140℃下蠕变时效后,维氏硬度和抗腐蚀性能都保持在较高的水平,160℃下合金的维氏硬度和抗腐蚀性能均较低。人工时效后,7050超高强铝合金中的主要强化相为大量弥散分布的η'相,蠕变时效后,晶内和晶界析出相尺寸略有减小,晶界析出相分布不连续,电化学腐蚀速率减小,合金抗腐蚀性能提高。

The 7050 ultra-high strength aluminum alloy was subjected to creep aging treatment.The mechanical properties and corrosion behaviors were studied by some tests including Vickers-hardness,intergranular corrosion and exfoliation corrosion.The microstructures were analyzed by optical microscope and transmission electron microscope.The effects of creep aging on microstructures and properties of the alloy were studied.The results show that the steady creep rate of the alloy is increased gradually with the increase of temperature and the rise of stress.Aging temperature is the main factor affecting the creep rate and corrosion resistance of the alloy.The relationship between the steady creep rate,creep stress and creep temperature of 7050 ultra-high strength aluminum alloy can be expressed as:ε=e(12.226)σ(1.66)exp(-120536/RT).After creep aging treatment,the Vickers-hardness,intergranular corrosion resistance and exfoliation corrosion resistance of the alloy are all improved.After creep aging at 120℃and 140℃,the hardness and corrosion resistance of the alloy all keep at high level.The hardness and corrosion resistance of the alloy are low under 160℃.After artificial aging,the main reinforcing phase of 7050 ultra-high strength aluminum alloy is a large number of dispersedη′phases.After creep aging,the size of the precipitated phases in the grains and on the grain boundaries are decreased slightly,the distribution of the precipitated phases at the grain boundaries is discontinuous,the electrochemical corrosion rate is decreased,and the corrosion resistance of the alloy is improved.