长期时效处理对21-4NWNb钢组织与性能的影响  

Effect of long-term aging on microstructure and properties of 21-4NWNb steel

作　　者：赵守忠 王守乾 朱治愿[1] 闵亮 徐超凡 沈佳宝 Zhao Shouzhong;Wang Shouqian;Zhu Zhiyuan;Min Liang;Xu Chaofan;Shen Jiabao(School of Materials Science and Engineering,Jiangsu University of Science and Technology,Zhenjiang Jiangsu 212000,China)

机构地区：[1]江苏科技大学材料科学与工程学院,江苏镇江212000

出　　处：《金属热处理》2024年第7期78-84,共7页Heat Treatment of Metals

摘　　要：研究了经过标准热处理(1050℃×30 min+750℃×4 h)的21-4NWNb钢在750℃长期时效过程中的组织转变和力学性能变化情况。结果表明,长期时效过程中21-4NWNb钢的晶粒尺寸变化不明显,时效200 h时,组织中分布有少量规则块状M_(23)C_(6)型碳化物,时效500 h以后,晶内逐渐出现σ相(AB)。21-4NWNb钢硬度在200 h时最高为324 HV,最大抗拉强度为971 MPa,伸长率为22.2%。时效200 h以后,随着时效时间的延长,其硬度和抗拉强度均表现为逐渐下降的趋势;时效2000 h后钢的伸长率降至15%以下。Microstructure evolution and mechanical properties change of the 21-4NWNb steel after standard heat treatment(1050℃×30 min+750℃×4 h)during long-term aging at 750℃were studied.The results show that the grain size of 21-4NWNb steel does not change obvious during long-term aging.When aged for 200 h,a small amount of regular block M_(23)C_(6) carbides are distributed in the steel.When the aging time extends to 500 h,σ phase(AB)gradually appears in the grain.The hardness of the 21-4NWNb steel reaches the highest value of 324 HV when aged for 200 h with a maximum tensile strength of 971 MPa and a elongation of 22.2%.With the prolong of aging time from 200 h,the hardness and tensile strength show a gradual decline,and the elongation of the steel drops below 15% after aging for 2000 h.

关 键 词：21-4NWNb钢 长期时效 Σ相 

分 类 号：TG156.1[金属学及工艺—热处理]