LC3低温用铸钢CCT曲线的测定和分析  

Determination and analysis of CCT curve of LC3 cryogenic cast steel

作　　者：陈坤 宫文国 常雪婷 尹衍升 Chen Kun;Gong Wenguo;Chang Xueting;Yin Yansheng(College of Ocean Science and Engineering,Shanghai Maritime University,Shanghai 201306,China;Shandong Yanshan Precision Machinery Co.,Ltd.,Jinan Shandong 271100,China)

机构地区：[1]上海海事大学海洋科学与工程学院,上海201306 [2]山东燕山精密机械有限公司,山东济南271100

出　　处：《金属热处理》2024年第12期137-141,共5页Heat Treatment of Metals

基　　金：国家重点研发计划(2022YFB3705303);上海市科委技术标准项目(21DZ2205700);上海深海材料工程技术中心项目(19DZ2253100)。

摘　　要：采用DIL 805A型全自动相变仪测定LC3低温用铸钢在0.05~150℃/s不同冷却速度下的膨胀曲线,采用切线法测定相变点Ac_(1)为700℃,Ac_(3)为849℃;结合显微组织分析和显微硬度确定实际转变产物,利用Origin软件绘制CCT曲线图。结果表明,冷却速度在0.05~2℃/s时,组织为铁素体+珠光体;在5~20℃/s时,组织为铁素体+珠光体+贝氏体;在30~50℃/s时,组织为贝氏体+马氏体;在80℃/s时,组织为马氏体+残留奥氏体;在100~150℃/s时,组织为全马氏体。随着冷却速度的增大,LC3低温用铸钢硬度逐渐提高,硬度由168 HV10增大至453 HV10。马氏体临界冷却速度在80℃/s左右。DIL 805A type fully automatic phase transformer was used to determine the expansion curve of LC3 cryogenic cast steel under different cooling rates between 0.05-150 ℃/s, and the tangent method was used to determine the phase transformation point Ac_(1) of 700 ℃ and Ac_(3) of 849 ℃. Combined with microstructure analysis and microhardness to determine the actual transformation products, and the CCT curve was plotted using Origin software. The results show that the microstructure is ferrite + pearlite when the cooling rate is 0.05-2 ℃/s, ferrite + pearlite +bainite when it is 5-20 ℃/s, bainite + martensite when it is 30-50 ℃/s, martensite + retained austenite when it is 80 ℃/s, and martensite when it is 100-150 ℃/s. Hardness of the LC3 cryogenic cast steel gradually increases from 168 HV10 to 453 HV10 with the increasing of cooling rate. Martensite critical cooling rate is about 80 ℃/s.

关 键 词：LC3低温铸钢 连续冷却曲线 切线法 临界冷却速度 

分 类 号：TG141[一般工业技术—材料科学与工程]