晶粒度对K492高温合金疲劳性能的影响  

Effects of Grain Size on Fatigue Properties of K492 Superalloy

作　　者：刘志远 刘勇军 刘鹏[2,3] 崔传勇[2] LIU Zhiyuan;Liu Yongjun;LIU Peng;CUI Chuanyong(China Aviation Development Hunan Institute of Power Machinery,Zhuzhou 412002,,China;Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China)

机构地区：[1]中国航发湖南动力机械研究所,株洲412002 [2]中国科学院金属研究所,沈阳110016 [3]中国科学技术大学材料科学与工程学院,合肥230026

出　　处：《材料研究学报》2018年第11期834-842,共9页Chinese Journal of Materials Research

基　　金：国家自然科学基金(51671189)~~

摘　　要：研究了晶粒度对K492镍基高温合金在700℃和800℃的疲劳性能的影响,并根据扫描电镜和透射电镜的结果分析了疲劳断裂的机理。结果表明,晶粒细化提高了K492合金700℃和800℃的疲劳性能。在700℃进行高周疲劳时在冶金缺陷或某个晶面处产生疲劳裂纹;疲劳实验后位错呈带状分布,γ'相形态不发生变化,位错以切过或Orowan绕过机制通过γ'相。在800℃高周疲劳时疲劳裂纹均在缺陷处产生,部分区域的位错组态与在700℃的实验结果相似,γ'相形态不发生变化。另一部分区域的γ'相发生筏化,位错分布在基体通道中,γ'相失去对位错的钉扎作用。在700℃低周疲劳时疲劳裂纹主要起始于样品表面。在800℃低周疲劳时,疲劳裂纹主要产生于样品次表面或某个晶面处。Effects of grain size on the fatigue properties of Ni-base superalloy K492at 700℃ and 800℃ with various grain sizes were investigated.The fatigue fracture mechanism is analyzed by scanning electron microscopy and transmission electron microscopy.The results show that grain refinement improves the fatigue properties of K492 at 700℃and 800℃.For high-cycle fatigue (HCF)at 700℃,fatigue cracks occur at the metallurgical defect or at a certain crystal plane.The distribution of dislocation configuration is band-like and the morphology of γphase does not change.The dislocations pass through the γ phase by shearing or Orowan loops passing.For HCF at 800℃ the fatigue cracks generated at the defects.In some regions the morphology of dislocation configuration was similar to that at 700℃ HCF and the morphology of γ phase does not change;In the other region,the γ phase rafts and dislocations distribute in the matrix channel,and the γ phase loses the pinning effect of dislocations.For low-cycle fatigue (LCF)at 700℃,fatigue cracks mainly originate from the surface.For LCF at 800℃,fatigue cracks mainly occur at the secondary surface or at a certain crystal plane.

关 键 词：金属材料 高温合金 晶粒细化 疲劳性能 位错组态 断裂机理 

分 类 号：TG146[一般工业技术—材料科学与工程]