Experimental investigation of tension and compression creep-ageing behaviour of AA2050 with different initial tempers
Experimental investigation of tension and compression creep-ageing behaviour of AA2050 with different initial tempers
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DOI：
10.1016/j.msea.2016.01.074
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发表时间：
2016-03
期刊：
影响因子：
6.4
通讯作者：
Yong Li;Z. Shi;Jianguo Lin;Yo-Lun Yang;B. Huang;Tsai-Fu Chung;J. R. Yang
中科院分区：
文献类型：
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作者：
Yong Li;Z. Shi;Jianguo Lin;Yo-Lun Yang;B. Huang;Tsai-Fu Chung;J. R. Yang
研究了不同初始状态（T34、T84和淬火态）的2050铝合金在155 °C、18 h、不同应力水平下的拉伸和压缩蠕变时效行为。通过间断蠕变-时效试验和随后的拉伸试验研究了相应的强化现象。此外，还用透射电子显微镜（TEM）观察了部分试样蠕变-时效后的显微组织，并分析了析出过程。在试验过程中发现，拉应力作用下的蠕变应变远大于压应力作用下的蠕变应变。在淬火态和预拉伸/自然时效态（T34）合金中均观察到一种新的“双主蠕变特征”，即在初始主蠕变+瞬态稳态蠕变阶段和第二主蠕变+第二稳态蠕变阶段之间存在一个蠕变应变速率逐渐增大的中间逆蠕变阶段。而对于峰值时效初始状态（T84）的合金，在拉伸蠕变-时效过程中观察到典型的第一蠕变阶段和稳态第二蠕变阶段，在150和175 MPa的压应力下发生的蠕变应变很小。这些现象的机制进行了讨论，在微观结构之间的相互作用变化的位错，溶质-基体结合和沉淀物，和它们对合金的抗蠕变性能的蠕变时效试验期间进行了分析。
Creep-ageing behaviour of aluminium alloy 2050 with different initial tempers (T34, T84 and as-quenched) has been experimentally investigated under both tension and compression creep-ageing conditions, with different stress levels at 155 °C for 18 h. Corresponding strengthening phenomena have been studied by interrupted creep-ageing tests and subsequent tensile tests. Moreover, the microstructures of some selected specimens after creep-ageing tests have been examined by transmission electron microscopy (TEM) and the precipitation process has been analysed. It has been found that creep strains under tensile stresses are much larger than those under compressive stresses during the tests. A new “double primary creep feature” has been observed in both the as-quenched alloys and the pre-stretched/natural-aged (T34) alloys, in which an intermediate inverse creep stage with an increasing creep strain rate locates between the initial primary+transient steady-state creep stages and the second primary+second steady-state creep stages. While for the alloy with peak-aged initial temper (T84), typical primary and steady-state secondary creep stages are observed during tension creep-ageing tests and little creep strain occurs under compressive stresses of 150 and 175 MPa. The mechanisms for these phenomena are discussed in terms of microstructural interactions among the changing dislocations, solute-matrix bonding and precipitates, and their effects on the creep resistance of the alloy during creep-ageing tests are analysed.