蠕变时效处理含钪7050铝合金耐蚀性研究

发布时间：2018-04-05 05:18

本文选题：蠕变时效　切入点：7050铝合金　出处：《郑州大学》2017年硕士论文

【摘要】：7050合金是一种在航空领域应用广泛的高强铝合金。本文作者在7050合金标准成分的基础上添加微量钪,制备了三种钪含量的7050合金样品,研究了钪对7050合金微观组织和力学性能的影响;通过对制备合金进行蠕变时效处理,研究了钪含量、变形量(指下压量)以及应力状态对蠕变时效处理含钪7050合金的晶间腐蚀、剥落腐蚀以及应力腐蚀行为的影响。主要研究内容和结果如下:(1)研究了钪对7050合金微观组织和力学性能的影响。结果表明:向7050合金中加入微量钪,可明显细化合金的铸态组织,并且随着钪含量的增加,细化效果有所增强,变形处理的含钪7050合金的纤维状组织也更加细小和均匀;与不含钪7050合金相比,含钪7050合金的硬度和拉伸性能均明显改善,且当钪含量为0.18wt.%时,合金具有最佳的力学性能,加入更多的钪,合金的力学性能并没有进一步提高,反而有下降趋势。(2)通过对制备合金进行蠕变时效处理,对比研究了钪含量对蠕变时效处理含钪7050合金的晶间腐蚀和剥落腐蚀行为的影响。结果表明:蠕变时效处理含钪7050合金的晶间腐蚀和剥落腐蚀抗力明显优于不含钪7050合金,而且,随着钪含量的增加,合金的晶间腐蚀和剥落腐蚀抗力均有所提高。(3)研究了蠕变时效处理过程中,变形量对含钪7050合金的晶间腐蚀和剥落腐蚀抗力的影响。结果表明:当变形量处在弹、塑性变形的临界区(变形量为7mm左右)时,含钪和不含钪7050合金都具有最好的耐腐蚀性能。但在塑性变形(如:变形量为12mm)条件下进行蠕变时效处理时,含钪和不含钪7050合金的晶间腐蚀和剥落腐蚀抗力则均有所下降。当合金的变形量处在弹性区(变形量0-5mm)时,变形量对蠕变时效处理含钪和不含钪7050合金的晶间腐蚀和剥落腐蚀抗力的影响有所不同。对于不含钪合金,增加变形量可提高合金的腐蚀抗力,而对于含钪合金,增加变形量却使合金的腐蚀抗力有所降低。(4)研究了蠕变时效处理过程中,应力状态对含钪7050合金晶间腐蚀和剥落腐蚀行为的影响。结果表明:在进行蠕变时效处理时,处在压应力状态下的合金的晶间腐蚀和剥落腐蚀抗力均优于处在拉应力状态下的合金。(5)采用慢应变速率拉伸试验,对比研究了钪含量和变形量对蠕变时效处理含钪7050合金的抗应力腐蚀性能的影响。结果表明:在变形量相同的情况下,加钪可明显降低7050合金的应力腐蚀敏感性指数,提高合金的应力腐蚀抗力,而且适当增加钪含量有利于降低合金的应力腐蚀敏感性。在钪含量相同时,变形量对蠕变时效处理含钪7050合金应力腐蚀敏感性的影响有类似的变化趋势。当变形量在弹性范围内(0-5mm)时,变形量增加,合金的应力腐蚀敏感性上升。而当变形量增加到弹、塑性变形的临界区(变形量为7mm左右)时,合金的应力腐蚀敏感性出现了大幅降低。继续增加变形量到塑性变形区(如:变形量为12mm)时,合金的应力腐蚀敏感性会明显回升。
[Abstract]:7050 Alloy is widely used in the field of aviation high strength Aluminum Alloy. This thesis is based on the addition of Trace Scandium standard components of 7050 Alloy, 7050 Alloy Samples of three kinds of scandium content were prepared, studied the influence of Scandium on the microstructure and mechanical properties of 7050 Alloy; creep aging treatment is carried out through the preparation of alloy study on the SC content, deformation (mean reduction) and stress state on the creep aging treatment of scandium containing 7050 Alloy intergranular corrosion, exfoliation corrosion and stress corrosion behavior. The main research contents and results are as follows: (1) study the effects of Scandium on the microstructure and mechanical properties of 7050 Alloy. The results show that the addition of Trace Scandium to 7050 Alloy, as cast microstructure can be refined obviously alloy, and with the SC content increased, the refining effect of enhanced deformation of fibrous tissue with scandium containing 7050 Alloy are more fine and are Uniform; compared with scandium containing 7050 Alloy, hardness and tensile properties of scandium alloy 7050 were significantly improved, and when the SC content is 0.18wt.%, the alloy has the best mechanical properties, adding more scandium, the mechanical properties of the alloy and no further increase, but a downward trend. (2) creep aging treatment based on the preparation of alloy, to study the influence of scandium content on creep aging of scandium containing 7050 Alloy intergranular corrosion and exfoliation corrosion behavior. The results show that the creep aging treatment of scandium containing 7050 Alloy intergranular corrosion and exfoliation corrosion resistance of 7050 Alloy containing scandium is better than not, moreover, with the increase of the SC content, alloy intergranular corrosion and exfoliation corrosion resistance were improved. (3) studied the creep aging process, the effect of deformation on the scandium containing 7050 Alloy intergranular corrosion and exfoliation corrosion resistance. The results show that when the deformation is elastic The critical region, plastic deformation (deformation is about 7mm), and not containing scandium scandium containing 7050 Alloy has the best corrosion resistance. But in plastic deformation (e.g. 12mm deformation) of creep aging conditions, and not containing scandium scandium containing 7050 Alloy crystal corrosion and exfoliation corrosion resistance is decreased. When the alloy deformation in elastic zone (deformation of 0-5mm), the effect of deformation on aging and creep of scandium scandium containing 7050 Alloy intergranular corrosion and exfoliation corrosion resistance is different. For scandium alloy, increase of deformation can improve the corrosion the resistance of the alloy, and the alloy containing scandium, increasing the amount of deformation but the corrosion resistance of the alloy decreases. (4) studied the creep aging process. The influence of stress state on the scandium containing 7050 Alloy intergranular corrosion and exfoliation corrosion behavior. The results showed that in creep aging treatment, In the compressive stress of the alloy intergranular corrosion and exfoliation corrosion resistance are superior in tensile alloy under stress. (5) using slow strain rate tensile test, a comparative study of the SC content and deformation on the creep aging of scandium alloy 7050 anti stress corrosion performance of the results. Showed that the deformation under the same amount, plus SC can significantly reduce the stress corrosion sensitivity index of 7050 Alloy, improve the alloy stress corrosion resistance, and increase the SC content of the alloy is lower stress corrosion sensitivity. The scandium content is similar to the creep deformation and aging treatment of 7050 Alloy containing scandium effect of stress corrosion sensitivity of a similar trend. When the amount of deformation in the elastic range (0-5mm), increasing the amount of deformation, stress corrosion sensitivity increased. When the alloy deformation increases to the bomb, the critical region of plastic deformation (deformation The stress corrosion cracking susceptibility of the alloy decreased significantly when 7mm or so. The stress corrosion cracking susceptibility of the alloy increased significantly when the deformation increased to the plastic deformation area (12mm =).

【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.21;TG166.3

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