MATERIALS DEVELOPMENT AND MICROSTRUCTURAL CONTROL FOR IMPROVING FATIGUE FRACTURE PROPERTIES IN FILM MATERIALS

(1)以纯铜薄膜为材料，制备了轧制方向平行于加载方向和垂直于加载方向的两种试样，进行了薄膜疲劳试验。其结果是，在垂直于滚动方向加载的膜中，滑移和裂纹在较少的循环次数和较低的应力幅下开始，而裂纹由于大的裂纹闭合而传播较慢。此外，有两种类型的试样之间的试样表面上的裂纹观察与轧制拉伸的晶粒的大的纵横比的差异。(2)对厚度为100μ m的工业纯铁薄膜进行轧制后分别在873 K、1073 K和1173 K进行退火处理，并制备了轧制方向平行于加载方向和垂直于加载方向两种试样进行薄膜疲劳试验。用EBSD系统进行的晶体学分析表明，退火后轧制织构的各向异性仍然存在，且两者存在差异 ...更多信息 裂纹观测中的试件类型。在相同的应力强度因子范围ΔK_<est>K（由裂纹张开位移计算）下，垂直于轧制方向加载的薄膜中疲劳裂纹的扩展速度更快。这可能是因为根据滚动方向和裂纹扩展方向之间的关系，滑移面是不同的。(3)用环氧树脂或扩散法将工业级铁膜粘接到钢基板上。当使用环氧树脂时，在热固化和冷却过程中由树脂的收缩变形引起的压缩残余应力在100 μ m厚度的膜中比在50 μm厚度的膜中大，因此增加了100 μm厚度的膜结合板的疲劳寿命。另一方面，在相同的有效应力强度因子范围内，由裂纹张开位移ΔK_<est>计算的疲劳裂纹扩展速率da/dN对于所有的环氧树脂粘接试样几乎相同，但树脂粘接试样的疲劳裂纹扩展速率da/dN相对大于扩散粘接试样。这表明由环氧树脂层粘结的膜本身的抗疲劳裂纹扩展性较低。少

(1) Using pure copper films, the two types of specimen that rolling direction was parallel and perpendicular to loading direction were prepared for a film fatigue testing. As a result, in the film loaded in the perpendicular direction to the rolling, slips and cracks were initiated at less number of cycles and lower stress amplitude, while a crack propagated slower because of the large crack closure. Also, there was a difference in crack observation on the specimen surface between the two types of specimen with the large aspect ratio of the grain stretched by rolling.(2) Commercially-pure iron films with the thickness of 100μ m were annealed at 873K, 1073K and 1173K after rolling, and the two types of specimen that rolling direction was parallel and perpendicular to loading direction were prepared for a film fatigue testing. The crystallographic analysis using EBSD system showed that the anisotropy of rolling texture remained after annealing, and there was a difference between the two … More types of specimen in crack observation. When compared at the same stress intensity factor range, ΔK_<est>K, evaluated from the crack opening displacement, fatigue cracks propagated faster in the film loaded to the perpendicular direction to the rolling. This was probably because the slip plane was different in accordance with the relationship between the rolling and crack propagation directions.(3) Commercial grade iron films were bonded to steel base plates by using epoxy resin or by diffusion. When using the epoxy resin, the compressive residual stress induced by a shrinkage deformation of the resin during the heat-curing and cooling process was larger in the 100 μm than the 50 μm thickness film, thus increasing the fatigue life in the 100 μm thickness film-bonded plates. On the other hand, under the same effective stress intensity factor range evaluated from crack opening displacements, ΔK_<est>, the fatigue crack propagation rate, da/dN, was almost the same for all the epoxy bonded specimens, but relatively larger in the resin-bonded than the diffusion-bonded film. This showed the lower fatigue crack propagation resistance of the film itself bonded by the epoxy resin layer. Less