激光沉积修复DD5合金的枝晶外延生长控制与显微组织特征  

Control of dendrite epitaxial growth and microstructure characteristics of laser deposition repaired DD5 alloy

作　　者：卞宏友 徐效文 刘伟军 王蔚 邢飞 王慧儒 Bian Hongyou;Xu Xiaowen;Liu Weijun;Wang Wei;Xing Fei;Wang Huiru(School of Mechanical Engineering,Shenyang University of Technology,Shenyang 110870,China)

机构地区：[1]沈阳工业大学机械工程学院,辽宁沈阳110870

出　　处：《红外与激光工程》2023年第5期130-142,共13页Infrared and Laser Engineering

基　　金：辽宁“百千万人才工程”资助项目(LNBQW2020B0050);辽宁省“兴辽英才计划”项目(XLYC1902022)。

摘　　要：采用DZ125高温合金粉末对DD5合金进行激光沉积修复,通过正交试验的方法,研究了激光功率、扫描速度和送粉量对单道单层沉积区枝晶外延生长的影响,实现了沉积区枝晶外延生长的控制。在此基础上,进行单道多层沉积修复试验,分析测量了单道多层沉积区的显微组织和硬度。结果表明:较低的热输入量和送粉量可显著提高沉积区枝晶外延占比;当激光功率为420 W、扫描速度为6 mm/s、送粉量为1.5 g/min时,单道单层沉积区枝晶外延占比约为100%。单道多层沉积区中下部为平面晶、沿沉积方向外延生长的柱状晶,顶部为等轴晶;沉积区γ′相不均匀地分布在γ相中,枝晶间区域的γ′相尺寸大于枝晶干区域的γ′相尺寸;沉积区底部短棒状MC碳化物沿枝晶间分布,且Ta元素含量较高;沉积区顶部的小块状以及八面体状MC碳化物随机分布。DD5合金基体平均显微硬度为425 HV_(0.5),沉积区平均显微硬度略高于基体,为449 HV_(0.5);与沉积区中部相比,沉积区底部和顶部的显微硬度略高,沉积区底部显微硬度最高。Objective DD5 nickel-based single-crystal(SX)alloy has been widely applied to manufacture the aeroengine turbine blades due to its excellent high-temperature strength and creep resistance.However,many types of damage to SX turbine blades,e.g.,blade tip erosion,crack,are unavoidable in the harsh working environment,which shortens the service life of SX turbine blades.Therefore,it is urgent to study the repair of damaged SX turbine blades.The laser deposition technology,which can provide high temperature gradients and allows the addition of controlled amounts of material to required locations,is beneficial to repair the damaged SX alloy parts.According to investigation on laser deposition repair of SX alloy by scholars,the damaged SX alloy can be successfully repaired by properly controlling laser process and repairing SX alloy with different materials has bright prospects.At present,minimal reports have discussed the laser deposition repair of DD5 SX alloy using different materials.Therefore,the DD5 SX alloys are repaired by laser deposition technology using the DZ125 superalloy powder.The influence of laser power,scanning velocity and powder-feeding on dendrite epitaxial growth is systematically investigated by the orthogonal experiment method.The microstructure and microhardness of the single multi-layer as-deposited sample are analyzed.This study is aimed at providing a guide for the repair of damaged DD5 SX alloy.Methods The gas-atomized DZ125 superalloy powders were used as the depositing materials in this experiment and the cast DD5 SX alloys with the crystallographic orientation((001)/[100])normal to the depositing surface were applied as the substrate.Firstly,the DD5 SX alloys were repaired by laser deposition technology.The influence of laser power,scanning velocity and powder-feeding on dendrite epitaxial growth is systematically investigated by the orthogonal experiment method.Then,the laser deposition experiment of single multi-layer was carried out.The microstructure of the single multi-layer as-depos

关 键 词：DZ125高温合金 DD5单晶合金 激光沉积修复 枝晶外延生长 显微组织 

分 类 号：TN249[电子电信—物理电子学]