热等静压制备TC4合金内筋圆筒件的组织与力学性能

Microstructure and mechanical properties of TC4 alloy cylinder with inner ribs prepared by hot isostatic pressing

采用有限元模拟技术研究TC4合金内筋筒形件在热等静压(HIP)过程中的致密化行为,通过响应面技术获得优化的HIP工艺参数,并开展优化工艺条件下的HIP实验;分别对HIP制备TC4合金内筋筒形件的不同部位开展致密度、力学性能测试以及微观组织和断口形貌表征。结果表明:TC4合金内筋筒形件的外表面优先致密,筒壁和筒底芯部的致密度最高,HIP压力对致密化的影响高于保温保压时间对致密化的影响;HIP制件筒壁和筒底的组织致密均匀、室温拉伸性能接近,筒壁室温拉伸性能均略优。350℃时,筒壁和筒底的拉伸性能差值进一步缩小,抗拉强度保持率达到近70%。室温和350℃拉伸变形试样均以韧性断裂为主的断裂特征。

The densification behavior of TC4 alloy inner ribbed cylindrical parts during hot isostatic pressing(HIP)was studied by using finite element simulation technology.The optimized HIP process parameters were obtained through response surface methodology.HIP experiments were conducted under the optimized process.The density and mechanical properties tests were conducted on different sampling positions of the TC4 alloy inner ribbed cylindrical parts prepared by the HIP.The microstructure and fracture morphology were also characterized.The results show that the outer surface of TC4 alloy inner ribbed cylindrical parts is preferentially densified,with the highest density at the center of the cylinder wall and bottom.The contribution of HIP pressure to densification is more significant than that of insulation and pressure holding time.The microstructures of the wall and bottom of the HIPed product are dense and uniform,with similar room temperature tensile properties.The room temperature tensile properties of the wall are slightly better.At temperature of 350℃,the difference in tensile properties of cylinder wall and bottom is further narrowed and the retention rate of tensile strength reaches nearly 70%.The tensile deformation specimens both at room temperature and 350℃exhibit fracture characteristics dominated by ductile fracture.