Si对一种9Cr铁素体/马氏体钢显微组织和力学性能的影响  

Effect of Si on Microstructure and Mechanical Properties of a 9Cr Ferritic/Martensitic Steel

作　　者：张乾坤 胡小锋[1] 姜海昌[1] 戎利建[1] ZHANG Qiankun;HU Xiaofeng;JIANG Haichang;RONG Lijian(CAS Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China)

机构地区：[1]中国科学院金属研究所中国科学院核用材料与安全评价重点实验室,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016

出　　处：《金属学报》2024年第9期1200-1212,共13页Acta Metallurgica Sinica

基　　金：中核集团领创科研项目,中国科学院青年创新促进会项目No.Y2021059;中国科学院战略重点研究项目No.XDA28040200。

摘　　要：基于ASME标准成分的P91钢,设计了一种Si增强型的9Cr铁素体/马氏体钢(记为H-Si钢)。利用OM、FESEM、TEM、EBSD、拉伸和冲击等分析和检测技术,对P91和H-Si合金钢铸态、均质化态、回火态和时效态(550℃时效3000 h)的显微组织和力学性能进行了研究。结果表明,Si增强后会在合金钢中引入体积分数为3.9%的δ铁素体,但通过均质化处理可以将其完全消除。回火处理后,H-Si钢因Si含量较高,会形成富Si层包裹M_(23)C_(6)的现象,该富Si层阻碍了M_(23)C_(6)的粗化长大,使M_(23)C_(6)的尺寸小于P91钢中M_(23)C_(6)的尺寸。与此同时,在550℃时效处理时该富Si层同样会减缓M_(23)C_(6)的长大,同时还促进了Laves相的形核和生长,造成时效态H-Si钢具有较细的M_(23)C_(6)和较粗的Laves相。回火态H-Si钢因较高的Si含量和较细的M_(23)C_(6),强度明显高于P91钢,而时效处理后因Laves相的析出,强度进一步提高。回火态P91和H-Si合金钢具有相近的冲击功(约210 J),断裂模式均为韧性断裂。时效处理后由于Laves相的析出,导致P91和H-Si合金钢的冲击功下降。因H-Si钢中Laves相的尺寸较大、数量较多,使H-Si钢出现了一定比例的解理区,导致冲击功下降更明显。Due to the worsening of environmental pollution and energy shortage,nuclear energy has become an increasingly important energy source,offering clean,high-energy,safe,and stable power to meet the needs of modern life and production.P91 steel is an excellent heat-resistant steel,widely used in nuclear power plants for its good mechanical properties,high thermal conductivity,and low irradiation swelling rate.However,with the emergence of lead and lead-bismuth eutectic(LBE)cooled fast reactors(LFRs),P91 steels inferior compatibility with LBE has limited its use in LFR construction.To address this issue,9Cr ferritic/martensitic steel with high Si content(H-Si steel)was designed in this study to develop a compatible structural material for LFR heat exchange tubes.In addition,the effects of Si on the microstructure and mechanical properties of as-cast,homogenized,tempered,and aged H-Si steel were investigated using various techniques,including OM,FESEM,TEM,EBSD,tensile,and impact tests.The results show that the increase in Si content leads to 3.9%δferrite(volume fraction)in as-cast H-Si steel,which can be eliminated completely by homogenization heat treatment.Tempering produces a Si-enriched layer around M_(23)C_(6)due to the high Si content in the H-Si steel,which can suppress the rapid growth of M_(23)C_(6)and maintain a smaller size of M_(23)C_(6)than that of M_(23)C_(6)in P91 steel.Meanwhile,the Sienriched layer can slow down the growth of M_(23)C_(6)and promote the nucleation and growth of the Laves phase during aging at 550°C,which induces smaller M_(23)C_(6)and larger Laves phase in aged H-Si steel than that in aged P91.Due to the higher Si content and smaller M_(23)C_(6),the tempered H-Si steel exhibits significantly higher strength than P91.After aging,the strength of H-Si steel further increases because of the precipitation of the Laves phase.Both tempered alloy steels have similar impact energy(about 210 J)and the fracture mode is ductile fracture.However,the precipitation of the Laves phase after aging dec

关 键 词：SI M_(23)C_(6) LAVES相 Δ铁素体 力学性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]