摘要
经常规锻造、近β锻造和β锻造的Tell(Ti—6.5Al—3.5Mo—1.5Zr—0.3Si)钛合金盘获不同的显微组织,对应了不同的断裂韧性。在常规锻造的等轴组织中,虽然可以观察到穿过等轴α相的二次裂纹,但裂纹扩展路径平直,分枝少,断裂表面光滑平整,因而断裂韧性低。近β锻造得到双态组织,由于等轴α相含量的减少,魏氏α相比例增多和形态的改变,二次裂纹增加,断裂韧性显著提高。在β锻造的网篮组织中,α条上的疲劳条带和二次裂纹明显增加,裂纹扩展路径曲折,分枝多,故断裂韧性最高。可见,显微组织影响盘件断裂韧性的主要因素在于,裂纹扩展过程中产生的裂纹分枝、疲劳条纹和二次裂纹的密度以及裂纹扩展路径的曲折程度。
Th rclation of microstructure to fracture feature and fracture-toughness of TCll(Ti-6.5Al-3.5Mo-1.5Zr-0.3Si)alloy compressor disks, which were forged by conventional, close-Beta and Beta forging, has been investigated by means of light graphy and SEM viewing. This experiment showed the change of microstructure strickly influenced the fracture-toughness of disks. Conventional close-Beta and Beta forging are correspondent equiaxed bemodel and basketweave structure. By observing and analysing, it is found that the main factor of fracture-toughness, which is influenced by microst ructure, lies in the crack branching, fatigue structions, the density of secondary cracks and tortuous degree of cracy path, produced in the process of crack propagation.
关键词
钛合金
断裂
显微组织
fatigue struction
crack branching
Alpha-platelet colnoy
