中文摘要：

激光修复试样由激光修复区、热影响区和锻件基体区组成。修复区由贯穿多个熔覆层呈外延生长的粗大β柱状晶组成,柱状晶内为编织细密的网篮组织,α相的尺寸极其细小。热影响区组织由基体的锻造双态组织向修复区组织过渡。修复试样经600℃,1 h炉冷退火后,β柱状晶晶界连续性基本没有受到影响,晶内α板条略有长大,长宽比减小。退火前后修复试样显微硬度测试结果表明,退火态试样各区显微硬度相比沉积态均略有增加,增幅仅5%。退火后修复试样的高温拉伸性能和高周疲劳性能结果显示,拉伸性能强度指标高于模锻件标准,塑性与模锻件标准相当。修复试样疲劳极限为295 MPa,达到Ti17模锻件标准的70%,并对其在不同加载模式下的失效行为和断裂机制进行了分析。

英文摘要：

The sample fabricated by laser solid forming（LSF） consists of laser repaired zone（RZ）,heat affected zone（HAZ） and forge substrate.The repaired zone consists of coarse columnar β grains which grow epitaxially from the substrate.And β grains are made of extremely fine basket-weave microstructure where a lot of fine acicular α phases precipitate on.Microstructure of heat affected zone transits from duplex microstructure to basket-weave microstructure.After 600 ℃,1 h furnace cooling annealing continuity of columnar,β grain boundaries have not been affected,and α laths grow slightly and length/width ratio of α laths decreases.Microhardness test shows that hardness value of annealed sample is 5% higher than that of as-deposited sample.The results of high temperature tensile properties and high cycle fatigue property of annealed samples suggest that compared with the forging standard,the tensile strength index is higher while ductility index corresponds to the standard.The fatigue limit is 295 MPa which reaches 70% of the forging standard.At last,failure behavior and fracture mechanism of laser repair samples under different loading modes are analyzed.