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为了研究择优取向对机械性能的影响,测定了高度织构化的Ti-6Al-4V材料的拉伸性能、高周疲劳强度和疲劳裂纹扩展特性。通过热形变处理产生三种不同的织构:基面型织构、基面/横向型织构和横向型织构,这三种织构都是同样的均匀等轴显微组织。研究发现,杨氏模量在107～126千兆牛顿/米~2之间变化,而屈服强度则为1055～1170兆牛顿/米~2(1兆牛顿=0.1020公斤/毫米~2——译者注)。塑性只受织构的轻微影响。在真空、实验室空气和3.5%NaCl溶液中进行了高周疲劳和疲劳裂纹扩展试验,结果表明,可以把实验室空气看作完全腐蚀的环境。当载荷垂直于基面时,在真空中测得的疲劳强度最高。但是,这些条件对空气和3.5%NaCl溶液环境具有最高的敏感性。业已发现,织构在真空内几乎不影响疲劳裂纹扩展,但在腐蚀环境内,平行于(0002)基面的裂纹长大要比重直于该基面的长大更快一些。为了阐明腐蚀对织构化材料疲劳性能的影响,研究了氢所起的关键作用。
In order to study the effect of preferred orientation on mechanical properties, the tensile properties, high cycle fatigue strength and fatigue crack growth properties of highly textured Ti-6Al-4V materials were measured. Three different textures are produced by thermal texturing: basal texture, basal / transversal texture, and transversal texture, all three of which are the same uniform, equiaxed microstructure. It has been found that the Young’s modulus varies from 107 to 126 gigaltons / m 2 and the yield strength is 1055 to 1170 trillion Newtons / m 2 (1 trillion Newton = 0.1020 kg / mm 2) Note). Plasticity is only slightly affected by texture. High-cycle fatigue and fatigue crack growth tests were performed in vacuum, laboratory air and 3.5% NaCl solution. The results show that laboratory air can be considered as a completely corrosive environment. When the load is perpendicular to the base surface, the fatigue strength measured in vacuum is the highest. However, these conditions have the highest sensitivity to air and to 3.5% NaCl solution environment. It has been found that texture does not affect fatigue crack growth in a vacuum at all but within the corrosive environment, crack growth parallel to (0002) base plane grows faster than that of the base plane. In order to elucidate the effect of corrosion on the fatigue properties of textured materials, the key role of hydrogen has been investigated.