摘要
采用激光立体成形（LSF）技术制备了Ti-6Al-4V平面应变断裂韧度（KIC）试样。沿沉积高度方向,沉积态组织呈现典型的β晶粒外延生长特性,β晶粒的平均宽度约为100-400 μm,长度可达若干厘米,β晶粒内由细密的针状α及α＋β板条组成。Ti-6Al-4V激光立体成形沉积态试样的KIC≥52.6 MPa·m1/2,达到锻件标准要求,不过,由于沉积态的组织特征,KIC具有典型的各向异性,与拉伸性能所表现的各向异性一致。β晶内细密α＋β编织的魏氏组织的抗裂纹扩展能力较强,使得裂纹扩展对β晶界非常敏感。当裂纹扩展面垂直于β晶界时,KIC最高;在裂纹沿β晶界扩展的情况下,单位面积内的晶界长度越长越曲折,则KIC越高。裂纹扩展方向与β晶界的夹角（0-90°）越大,β晶粒越细小,裂纹扩展越困难。
Samples of Ti-6Al-4V used in the test of plane strain fracture toughness （KIC） test is fabricated by laser solid forming （LSF）. Primary β grain,with a characteristic of epitaxial growth along the depositional direction,shows an average width of 100-400 μm and length of several centimeters. Within β grains,lathy α needles and fine-weaved dense Widmanstatten α＋β laths are observed. KIC≥52.6 MPa·m1/2 reaches the forging standard. And as same as the tensile property of LSF Ti-6Al-4V sample,KIC property presents remarkable anisotropism which is caused by the microstructure characteristic. Fine-weaved dense Widmanstatten α＋β laths owns strong ability in anti-crack-propagation,in result,crack-propagation shows sentivites to β grain boundary. If crack propagation runs the direction perpendicular to β grain boundary,KIC value reaches maximum;if crack propagation runs the direction along β grain boundary,the longer the boundary,the higher the KIC value. It is more easier for crack propagation with a small angle between crack-propagation direction and β grain boundary（0-90°）. The bigger angle and smaller β grain both result in difficulties in crack-propagation.
出处
《中国激光》
EI
CAS
CSCD
北大核心
2009年第12期3210-3214,共5页
Chinese Journal of Lasers
基金
中国博士后科学基金(20090451394)
凝固技术国家重点实验室自主研究项目(16-TZ-2007)资助课题
