Ti-6Al-4V型材的显微组织及性能研究

Study on property and microstructure of Ti-6Al-4V extrusion

为了研究截面形式及尺寸对钛合金型材的静力性能、损伤疲劳性能水平及其显微组织的影响,采用不同厚度截面的对比评价方法,对Ti-6Al-4V合金型材不同厚度截面的静力拉伸性能、疲劳及损伤容限性能进行研究,并对不同截面型材的微观组织进行了对比分析。结果表明,拉伸性能随着截面厚度尺寸的增大而降低,断裂韧性随厚度尺寸增大而升高,厚截面尺寸的“T”型材的疲劳性能和平面应变断裂韧性最高。不同截面尺寸的Ti-6Al-4V合金型材,厚截面尺寸型材的晶界组织较为明显,降低了静强度性能的同时提升了疲劳及损伤容限性能,因此静强度性能随着型材截面厚度尺寸的增大而降低,疲劳性能、断裂韧性、断后伸长率和断面收缩率随截面厚度尺寸的增大而提高。工程用钛合金Ti-6Al-4V型材可参考静强度、疲劳性能、断裂韧性及成形性能与截面厚度的对应关系进行型材零件外形设计。

Properties and microstructure tests were carried out in Ti-6Al-4V extrusion under different transections to investigate the strength,damage tolerance and fatigue behaviors of different thickness of extrusion,as well as the contrastive analysis on microstructure of Ti-6Al-4V extrusion.The results indicate that tensile strength is lower while the thickness is higher,the fracture toughness is higher while the thickness is higher,the‘T’extrusion with higher thickness has higher fatigue and fracture toughness properties.In thicker cross-section of Ti-6Al-4V extrusion,there are clear grain boundary structures,and the mechanical properties are lower while fatigue and fracture toughness performances are higher,therefore,Ti-6Al-4V extrusion parts could be designed referring to the relationship between material properties and cross-section thickness in engineering.