等温热处理对U-2Nb合金力学性能的影响  

Effects of Isothermal Heat Treatment on Mechanical Properties of U-2Nb Alloy

作　　者：芮克强 尹嘉清 莫文林 汪青海 法涛[1] Rui Keqiang;Yin Jiaqing;Mo Wenlin;Wang Qinghai;Fa Tao(Institute of Materials,China Academy of Engineering Physics,Mianyang 621900,China;Rocket Force Equipment Department,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院材料研究所,四川绵阳621900 [2]火箭军装备部驻绵阳地区第二军事代表室,四川绵阳621900

出　　处：《稀有金属材料与工程》2021年第1期271-278,共8页Rare Metal Materials and Engineering

基　　金：核基础科学挑战专题(TZ2016004);国家重点研发计划(2016YFB070040401);国家自然科学基金(51701193)。

摘　　要：采用光学显微镜、扫描电镜、拉伸、压缩实验等分析测试方法,系统地研究了U-2Nb合金450~635℃的等温相变过程及其对应的力学性能变化,对结构与性能的关联做了分析总结。结果表明,U-2Nb合金在550~635℃的等温热处理过程中存在两类特征鲜明的显微组织样貌,影响它们力学性能的主要因素是针状组织或者胞状组织的片层间距,受温度与时间的共同影响。片层间距主要取决于其形成温度,温度越高,片层间距越大,强度随之降低,塑性随之提升,等温时间与片层间距呈正相关。这一温区内获得的最好综合性能为延伸率22%,断面收缩率27.4%,抗拉强度875 MPa,屈服强度410 MPa。在450~500℃进行淬火并回火的样品主要组织形貌特征为针状马氏体与回火形成的团状组织共存状态,影响其力学性能的主要因素可能是针状马氏体的织构与回火生成的颗粒状组织的分布与大小,其整体强度高,均在1000 MPa以上,塑性差,延伸率与断面收缩率均在5%以内。等温温度对其强度的影响相对塑性更大,延长等温时间对其塑性有微弱改善。The phase transformation of U-2Nb alloy under isothermal condition and the mechanical properties corresponding to the morphological changes were studied within 450~635℃.By applying the optical microscope,scanning electron microscope techniques,and tensile and compression tests,the relationship between the structure and properties was discussed.The results show that the alloy has two distinct microstructure features during isothermal heat treatment from 550℃to 635℃,The main factor affecting the strength and plasticity is the lamellar spacing of the dual-phase in the range of 550~635℃.which is mainly determined by the formation temperature.The higher the temperature,the greater the lamellar spacing,the lower the strength,and the higher the plasticity.The isothermal holding time is positively correlated to the lamellar spacing.The best general properties obtained in this study are elongation of 22%,reduction area of 27.4%,tensile strength of 875 MPa and yield strength of 410 MPa.Quenching and annealing techniques were applied for samples treated at the temperature within 450~500℃.The main factors influencing the mechanical properties within this temperature range are speculated to be the texture of the acicular martensite and the distribution or size of the granular structure.All samples with quenching+annealing treatment show strength higher than 1000 MPa,but with low plasticity.Elongation and reduction of area are within 5%.The annealing temperature affects the strength much more than plasticity.The plasticity improves slightly by extending the annealing time.

关 键 词：铀铌合金 等温热处理 力学性能 片层结构 

分 类 号：TL214[核科学技术—核燃料循环与材料]