新型耐热合金SP2215组织与性能的关联性  

Correlation Between Microstructure and Properties of New Heat-Resistant Alloy SP2215

作　　者：梁凯 姚志浩[1] 谢锡善[1] 姚凯俊 董建新[1] LIANG Kai;YAO Zhihao;XIE Xishan;YAO Kaijun;DONG Jianxin(School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《金属学报》2023年第6期797-811,共15页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目Nos.51771017和52271087

摘　　要：针对新型SP2215耐热合金,通过一系列持久及冲击实验,研究了其在不同温度和时间时效处理后组织与性能之间的关联性。结果表明,SP2215合金具有优良的高温组织稳定性,在时效过程中会析出富Cu相、MX相、NbCrN相和M_(23)C_(6)等多种纳米级析出相。在时效早期,随着时效温度升高和时效时间的延长,析出相迅速增多,由于析出相的强化作用,合金的强度迅速增加;同时,合金的冲击韧性显著降低,并发生沿晶断裂,JMA相变动力学模型定量计算表明其主要与M_(23)C_(6)碳化物在晶界的连续析出与长大有关。在时效后期,析出相逐渐保持稳定,无有害相析出,晶粒度始终保持在4.5~5级,优异的高温组织稳定性使得SP2215耐热合金在时效后期具有稳定的力学性能,650和700℃的1×10^(5) h持久强度分别达到120和70 MPa级别,可实现对HR3C、Super304H等同类耐热合金的国产替代。With the improvement of the steam parameters of thermal power units,the requirements put forward for the stress rupture strength and structural stability of heat-resistant materials for boiler superheater/reheater pipes become higher.SP2215,as a new heat-resistant alloy,is an excellent candidate for 620-650℃ ultra-supercritical boiler superheater/reheater.In this study,the correlation between microstructure evolution and properties of the SP2215 heat-resistant alloy aging at different temperatures and time was studied via a series of creep and impact tests.The results show that the SP2215 alloy has excellent microstructure stability in high-temperature condition.Moreover,various nanoscale precipitations such as Cu-rich,MX,NbCrN,and M_(23)C_(6)phases occur during aging.In the early period of aging,with the increase in aging temperature and aging time,the precipitations increase rapidly,improving the strength of the material;however,the impact toughness of the SP2215 alloy decreases considerably,with substantial intergranular fracture caused by the continuous precipitation and growth of M_(23)C_(6)at the boundary,as shown with the quantitative calculation using the JMA model.In the late period of aging,the precipitations gradually stabilize,and the grain size remains in the range of 4.5-5 grade.As a result,the 1×10^(5) h stress rupture strength of the SP2215 alloy at 650 and 700℃still remain more than 120 and 70 MPa,respectively.Hence,the alloy can be used as a domestic replacement for foreign HR3C,Super304H,and other similar heat-resistant alloys.

关 键 词：SP2215耐热合金 长期时效 析出相 持久强度 性能 

分 类 号：TG132.3[一般工业技术—材料科学与工程]