时效处理对新型耐热钢组织及力学性能的影响  

Effect of aging treatment on structure and mechanical properties of new heat-resistant steels

作　　者：杜京伦 杨苏冰 丁恒楠 王资兴 刘天 罗锐[1] DU Jinglun;YANG Subing;DING Hengnan;WANG Zixing;LIU Tian;LUO Rui(School of Materials Science and Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu,China;School of Agricultural Engineering,Jiangsu University,Zhenjiang 212013,Jiangsu,China;Institute of Novel Metals and Applied Technologies,Jiangsu Industrial Technology Research Institute,Changshu 215506,Jiangsu,China)

机构地区：[1]江苏大学材料科学与工程学院,江苏镇江212013 [2]江苏大学农业工程学院,江苏镇江212013 [3]江苏省产业技术研究院先进金属材料及应用技术研究所,江苏常熟215506

出　　处：《钢铁》2024年第7期130-138,共9页Iron and Steel

基　　金：江苏省自然科学基金资助项目(BK20220548)。

摘　　要：新型含铝奥氏体耐热钢(AFA)在650~700℃温度范围内,具有组织稳定、高温性能优异以及制备成本较低等优点而成为超超临界火电机组的候选材料。为了系统阐明新型含铝奥氏体耐热钢在700℃下的第二相短时析出行为及与力学性能的关系,采用时效热处理、第二相析出粗化模型和综合力学试验相结合的方法,分析了700℃短时(≤500 h)时效对新型含铝奥氏体耐热钢Fe-18.4Cr-31Ni-1Nb-2.9Al(质量分数,%)的微观结构和力学性能的影响。研究结果表明,Laves相和B2-Ni Al相尺寸会随着时效时间的延长而逐渐增大。当时效至20 h,Laves相开始沿晶界析出,随着时效时间的延长,其尺寸粗化并覆盖晶界。相比之下,100 h时B2-Ni Al相在晶内析出,并由短棒状长为针状。随着时效时间从100 h延长至500 h,Laves相和B2-Ni Al相的平均尺寸从449 nm增加到706.9 nm。用Lifshitz-Slyozov-Wanger(LSW)粗化模型理论定量分析Laves相和B2-Ni Al相粗化动力学和等温时效时间的关系。计算得析出相的粗化速率k为1.9258×10^(-27)m^(3)/s,表明Laves相和B2-Ni Al相的长大速率由溶质原子扩散所控制。基体中Laves相和B2-Ni Al相的析出导致硬度和高温拉伸性能的增强。0~500 h,硬度持续增加,而抗拉强度先增加后降低。这是由于在0~200 h,Laves相和弥散的B2-Ni Al相析出,而200~500 h,B2-Ni Al相长大,使得抗拉强度降低,而伸长率增加。与未时效状态的抗拉强度528 MPa,伸长率76%相比,500 h时效后,其抗拉强度增至579 MPa,伸长率为52%。The new alumina-forming austenitic heat-resistant steel(AFA)has become a candidate material for ultra-supercritical thermal power units because of its stable microstructure,excellent high-temperature performance,and low preparation cost in the temperature range of 650-700℃.The new alumina-forming austenitic heat-resistant steel can be used for the thermal power units of ultra-supercritical thermal power plants.In order to systematically elucidate the short-time precipitation behavior of the second phase of the new alumina-forming austenitic heat-resistant steel at 700℃ and the relationship with the mechanical properties,the effect of short-time(≤500 h)aging at 700℃ on the microstructure and mechanical properties of the new alumina-forming austenitic heat-resistant steel Fe-18.4Cr-31Ni-1Nb-2.9Al(mass percent,%)has been analyzed using a combination of aging heat treatment,the second-phase precipitation model of coarsening,and the comprehensive mechanical test.The results show that the size of Laves and B2-NiAl phases increases gradually with the aging time.When aging to 20 h,the Laves phase starts to precipitate along the grain boundaries,and its size coarsens and covers the grain boundaries with the extension of aging time.In contrast,at 100 h,the B2-NiAl phase precipitates within the grain and grows from a short bar to a needle.The average size of the Laves and B2-NiAl phases increased from 449 nm to 706.9 nm with the extension of the aging time from 100 h to 500 h.The relationship between the coarsening kinetics and isothermal aging time of the Laves and B2-NiAl phases was quantitatively analyzed using the Lifshitz-Slyozov-Wanger(LSW)coarsening model theory.The coarsening rate k of the precipitated phases was calculated to be 1.9258×10^(-27) m^(3)/s,indicating that the growth rates of the Laves and B2-NiAl phases are controlled by the diffusion of solute atoms.The precipitation of Laves and B2-NiAl phases in the alloys leads to enhancement of hardness and high temperature tensile properties.The hardness

关 键 词：新型含铝奥氏体耐热钢 时效 析出相 粗化速率 力学性能 

分 类 号：TG142.73[一般工业技术—材料科学与工程] TG156.92[金属学及工艺—金属材料]