Microstructure features of 12 MnNiVR pressure vessel steel welded joint deposited by the high heat input electrogas welding have been systematically investigated. It is revealed that the welded joint is featured by a ...Microstructure features of 12 MnNiVR pressure vessel steel welded joint deposited by the high heat input electrogas welding have been systematically investigated. It is revealed that the welded joint is featured by a heterogeneous juxtaposition. The coarse grained heat-affected zone(CGHAZ) primarily consists of lath bainites and minor granular bainites. The fine grained heat-affected zone(FGHAZ) is dominated by polygonal ferrites, pearlites, and fine cementite particles. Moreover, electron backscatter diffraction results further demonstrate that the CGHAZ is populated by coarse prior austenite grains(PAGs) with high frequency(61.3%) of low angle grain boundaries(LAGBs). On the other hand, the FGHAZ is filled with fine PAGs with a lower frequency(19.6%) of LAGBs. Such microstructural differences may likely contribute to differed mechanical properties for samples tested at designed positions.展开更多
从标准规范、材料、结构等方面介绍了10×104m3大型浮顶油罐的设计要点。着重论述了10×104m3以上大型油罐设计规范的选用及国际上常用的储罐设计规范日本工业标准JIS B 8501和美国石油协会标准API650的区别;并对国产12MnNiVR...从标准规范、材料、结构等方面介绍了10×104m3大型浮顶油罐的设计要点。着重论述了10×104m3以上大型油罐设计规范的选用及国际上常用的储罐设计规范日本工业标准JIS B 8501和美国石油协会标准API650的区别;并对国产12MnNiVR钢板和进口SPV490Q钢板在化学成分、力学和工艺性能进行对比分析。阐述了单盘浮顶和双盘浮顶的优缺点及选用原则,对3种常用的浮顶排水系统进行了比较和说明了常用的防腐结构。展开更多
The weldability of 12MnNiVR was examined in terms of the simulated HAZ continuous cooling transformation (SH-CCT) diagram,microstructure and mechanical properties of the simulated coarse grain heat-affected zone (CGHA...The weldability of 12MnNiVR was examined in terms of the simulated HAZ continuous cooling transformation (SH-CCT) diagram,microstructure and mechanical properties of the simulated coarse grain heat-affected zone (CGHAZ).When t 8/5 is shorter,the microstructure mainly consists of lath bainite.When t 8/5 is 60 s,the microstructure becomes coarser bainite.Some acicular ferrite appears beside lath bainite when t 8/5 =100s.Finally,a microstructure composed of polygonal ferrite,acicular ferrite,and small amount pearlite is obtained with a small amount of bainite at t 8/5 】100s.With the increase of t 8/5,the hardness of CGHAZ decreases considerably.The minimum impact toughness of CGHAZ appears at t 8/5 =100s.The hardness and the toughness of CGHAZ remain above the specified values for steel 12MnNiVR.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51622401, 51628402, 51861145312 and 51861130361)the National Key Research and Development Program of China (2016YFB0300602)+3 种基金the Research Fund for Central Universities (No. N172502004)State Key Laboratory of Solidification Processing, Northwestern Polytechnical University (No. SKLSP201805)the Global Talents Recruitment Program endowed by the Chinese Governmentsupport from Jiangyin Xingcheng Special Steel Works Co., Ltd.
文摘Microstructure features of 12 MnNiVR pressure vessel steel welded joint deposited by the high heat input electrogas welding have been systematically investigated. It is revealed that the welded joint is featured by a heterogeneous juxtaposition. The coarse grained heat-affected zone(CGHAZ) primarily consists of lath bainites and minor granular bainites. The fine grained heat-affected zone(FGHAZ) is dominated by polygonal ferrites, pearlites, and fine cementite particles. Moreover, electron backscatter diffraction results further demonstrate that the CGHAZ is populated by coarse prior austenite grains(PAGs) with high frequency(61.3%) of low angle grain boundaries(LAGBs). On the other hand, the FGHAZ is filled with fine PAGs with a lower frequency(19.6%) of LAGBs. Such microstructural differences may likely contribute to differed mechanical properties for samples tested at designed positions.
文摘从标准规范、材料、结构等方面介绍了10×104m3大型浮顶油罐的设计要点。着重论述了10×104m3以上大型油罐设计规范的选用及国际上常用的储罐设计规范日本工业标准JIS B 8501和美国石油协会标准API650的区别;并对国产12MnNiVR钢板和进口SPV490Q钢板在化学成分、力学和工艺性能进行对比分析。阐述了单盘浮顶和双盘浮顶的优缺点及选用原则,对3种常用的浮顶排水系统进行了比较和说明了常用的防腐结构。
文摘The weldability of 12MnNiVR was examined in terms of the simulated HAZ continuous cooling transformation (SH-CCT) diagram,microstructure and mechanical properties of the simulated coarse grain heat-affected zone (CGHAZ).When t 8/5 is shorter,the microstructure mainly consists of lath bainite.When t 8/5 is 60 s,the microstructure becomes coarser bainite.Some acicular ferrite appears beside lath bainite when t 8/5 =100s.Finally,a microstructure composed of polygonal ferrite,acicular ferrite,and small amount pearlite is obtained with a small amount of bainite at t 8/5 】100s.With the increase of t 8/5,the hardness of CGHAZ decreases considerably.The minimum impact toughness of CGHAZ appears at t 8/5 =100s.The hardness and the toughness of CGHAZ remain above the specified values for steel 12MnNiVR.
