K465高温合金短时超温后的显微组织退化及拉伸性能  

Microstructural Degradation and Tensile Properties of K465 Equiaxed-cast Superalloy After Short-time Overheating

作　　者：郭小童 郑为为[1] 肖程波 郑运荣[1] 冯强[1] GUO Xiao-tong;ZHENG Wei-wei;XIAO Cheng-bo;ZHENG Yun-rong;FENG Qiang(State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing,Beijing 100083,China;Science and Technology on Advanced High Temperature Structural Materials Laboratory,AECC Beijing Institute of Aeronautical Materials,Beijing 100095,China)

机构地区：[1]北京科技大学新金属材料国家重点实验室,北京100083 [2]中国航发北京航空材料研究院先进高温结构材料重点实验室,北京100095

出　　处：《材料工程》2018年第10期77-86,共10页Journal of Materials Engineering

基　　金：国家高技术研究发展计划项目(2012AA03A513);教育部支撑计划重点项目(625010337)

摘　　要：航空发动机涡轮叶片在非正常工况下服役会发生短时超温的现象,导致叶片严重损伤。本工作利用高温拉伸实验设备,对航空发动机涡轮叶片用K465合金在1180~1270℃短时超温条件下的瞬时拉伸性能进行了测试。利用SEM、XRD和物理化学相分析的方法观察和定量表征拉伸前后的显微组织,研究了短时超温过程中显微组织的演变规律及其对拉伸性能的影响。结果表明:随超温温度增加,K465合金中γ′相、碳化物和晶界γ′膜逐步回溶;γ′相形成元素在枝晶间的富集导致枝晶间γ′相完全溶解温度显著高于枝晶干。在1270℃下,晶界与枝晶间残余共晶处发生初熔。合金的屈服强度随着超温温度的增加显著降低,由1000℃时的439MPa急剧下降至1180℃时的85MPa和1240℃时的26MPa。一次γ′相与晶界γ′膜的回溶及初熔是影响拉伸性能的主要因素。Turbine blades of aircraft engines may suffer serious degradation caused by overheating service exposures.In this paper,microstructure characteristics and tensile properties of K465 alloy,which is an equiaxed cast superalloy and widely used in turbine blades and vanes,were investigated after overheating treatment at 1180~1270℃.The microstructure before and after overheating was also examined and quantitatively characterized using SEM,XRD and physicochemical phase analysis.The relationship between microstructural degradation after overheating and tensile properties was investigated.The results indicate that primaryγ′phase,carbides and grain boundaries are gradually dissolved in K465 alloy with increasing the overheating temperature;γ′phase distributed in the interdendritic region has a higher dissolution temperature than that in the dendrite core region due to a higher content ofγ′phase forming elements.Incipient melting mainly occurs at the residual eutectic region and grain boundaries at 1270℃.The tensile properties are decreased significantly with increasing the overheating temperature,the yield strength was 439MPa at 1000℃and dramatically decreased to 85MPa and 26MPa at 1180℃and 1240℃,respectively.The tensile properties are mainly influenced by the dissolution behaviors of primaryγ′phase andγ′film along grain boundaries as well as the influence of incipient melting.

关 键 词：K465合金 涡轮叶片 超温 显微组织 拉伸性能 

分 类 号：TG132.32[一般工业技术—材料科学与工程] TG156.1[金属学及工艺—合金]