Hastelloy C-276合金多道次退火晶粒团簇组织的演变  

Microstructure Evolution of Grain Cluster in Hastelloy C-276 Alloy during Multi-Path Annealing

作　　者：张晓宇 钟军 赵军 郭胜利 孟建涛 Zhang Xiaoyu;Zhong Jun;Zhao Jun;Guo Shengli;Meng Jiantao(College of Material Engineering,North China Institute of Aerospace Engineering,Langfang 065000,China;National Engineering and Technological Research Center for Nonferrous Metal Composites,General Research Institute for Nonferrous Metals,Beijing 100088,China;Hebei Huizhong Pipeline Equipment Co.Ltd.,Cangzhou 061300,China)

机构地区：[1]北华航天工业学院材料工程学院,河北廊坊065000 [2]有色金属工程技术研究院有限公司国家有色金属复合材料工程技术研究中心,北京100088 [3]河北汇中管道装备有限公司,河北沧州061300

出　　处：《稀有金属》2021年第9期1053-1061,共9页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(50834008);北华航天工业学院博士科研启动基金项目(BKY-2017-02);河北省高等学校科学技术研究重点项目(ZD2018239);河北省高等学校科学技术研究项目(QN2019221);廊坊市科技局科学技术研究与发展计划项目(2018011049)资助。

摘　　要：采用电子背散射衍射(EBSD)技术研究了固溶处理后Hastelloy C-276合金,在5%变形条件下,不同温度多道次退火热处理中Σ3^(n)(n=1,2,3…)晶粒团簇及晶界特征分布演变规律。结果表明,两步退火热处理可以明显改善合金晶界特征分布,小变形样品经1000℃低温退火5 min后,再进行1100℃高温退火15 min热处理,晶粒组织发生再结晶,产生较多孪晶组织,形成内部互有Σ3^(n)取向关系的大尺寸晶粒团簇组织,Σ(9+27)/Σ3达到了0.125,特殊晶界比例达到78.8%,晶界特征分布得到优化。初始退火温度较高会使得变形储存能迅速释放,大角度晶界快速迁移,不利于产生Σ3退火孪晶晶界;而较长时间二次退火也不利于晶界反应,使得Σ9和Σ27晶界比例降低。退火过程中产生较多Σ9和Σ27晶界是晶界特征分布优化的关键。而过高的初始退火温度或过长的二次退火时间,抑制或消除了退火孪晶的产生,无法形成大尺寸晶粒团簇组织。Hastelloy C-276 was a type of Ni-Cr-Mo superalloy,and had been widely used as one of critical components in aerospace,chemical and nuclear industries because of its excellent corrosion resistance to acids and high temperature strength.Intergranular corrosion was a serious damage phenomenon in nuclear industries under complex working environments.Especially,it usually occurred at intersection sites of grain boundaries in materials,and thus led to material failure.Since intergranular corrosion among grain boundaries was a key factor to impact the lifetime of high temperature service of superalloys,how to improve the resistance to intergranular corrosion in superalloys had become an important scientific research topic.As we had known,grain boundaries played an important role in material properties.Furthermore,a so-called“grain boundary engineering(GBE)”had aimed at improving the resistance to intergranular corrosion by optimizing the grain boundary character distribution(GBCD).For example,the so-called“coincidence site lattice(CSL)”boundaries with higher ordering degree,lower interface energy and stronger resistance to grain boundary failure etc.were increased by means of the thermal-mechanical processing in the GBE,in which the low-Σ CSL boundaries(Σ≤29)were called“special grain boundaries”.Therefore,the GBE had been regarded as an effective technology for various superalloys with low stacking fault energy by increasing the fraction of special grain boundaries in materials.Because of those special grain boundaries,some highly twinned grain clusters with large sizes were typical microstructures produced by the GBE,which was the main reason of enhancing the intergranular corrosion resistance.Thus,in superalloys,all of grains would possess Σ3^(n) mutual misorientations regardless whether they were adjacent or not.Moreover,along the penetration path in grain clusters,intergranular corrosion would stop its forward step if it encountered a triple junction composed of special grain boundaries.While it mig

关 键 词：Hastelloy C-276合金 多道次退火 晶粒团簇 特殊晶界 

分 类 号：TK91[动力工程及工程热物理]