论文部分内容阅读
过去关于铝和铝铜合金的研究工作指出,在疲劳载荷过程中的能量消耗(△E)所发生的变化可以分成两个不同的阶段。第一阶段相当于位错的被钉札,在第二阶段里△E的再上升则表示已有粗滑移区出现。为了进一步验证这种看法,在本文中用含镁量为0.52,0.91,3.46和5.15％的铝合金进行了扭转疲劳试验,测定了经过各种应力循环数N以后的滞后迴线的面积,从而算出在每次循环中的能量消耗△E。在疲劳载荷经过不同循环数后,试样表面进行金相观测的结果指出,对于所用的合金而言,滑移痕迹的变化都表现出两个明显不同的阶段。在第一阶段里,常常观察到几组细而直的滑移线均匀分布在一个晶粒内。在第二阶段里,某一组滑移线变得集中而粗化成簇。一般而言,在镁含量较低(0.52,0.91％)的合金里,以及当扭应变较大时,粗滑移区出现得较早。 将所观察到的△E-N曲线的变化与粗滑移区的出现做了比较,并且考虑到在疲劳载荷过程中第一阶段和第二阶段的△E可能发生重迭的情况,指出了试样里出现粗滑移区可以引起△E在疲劳后期的再上升。这与过去关于铝和铝铜合金所得结果相合。 本文还讨论了位错在疲劳载荷第一阶段里被溶质原子气团所钉札的状态与粗滑移区的随后形成的联系。
In the past research work on aluminum and copper-aluminum alloys pointed out that the change in energy consumption (ΔE) during fatigue loading can be divided into two distinct phases. The first stage is equivalent to the pinnacle of dislocation, in the second stage △ E and then rise that there have been coarse slip zone. In order to further verify this view, torsional fatigue tests were carried out in this paper with aluminum alloys containing 0.52, 0.91, 3.46 and 5.15% Mg, and the area of hysteresis loop after various stress cycles N was measured. Calculate the energy consumption in each cycle △ E. The results of metallographic examination of the specimen surface after fatigue loading passed through different numbers of cycles indicate that for the alloy used, the change of the slip marks shows two distinct stages. In the first stage, it is often observed that several sets of thin and straight slip lines are evenly distributed in one crystal grain. In the second phase, a group of slip lines become concentrated and coarser into clusters. In general, coarse slip zones occur earlier in alloys with lower magnesium content (0.52, 0.91%), and when the torsional strain is greater. The observed change in the Δ EN curve is compared with the appearance of the coarse slip zone, and considering that the ΔE in the first and second phases may overlap during the fatigue load, the sample Rough slip in the region can cause △ E in the latter part of the fatigue rise. This is in line with the previous results on aluminum and aluminum-copper alloys. The paper also discusses the relationship between the state of dislocations pinned by solute atomic air masses and the subsequent formation of coarse slip zones during the first stage of fatigue loading.