33 mmX80M钢母材及环焊接头的微观组织和析出物分析

Analysis of microstructure and precipitation of base metal and girth weld joint of 33 mm X80M steel

采用OM,SEM,TEM等手段对33 mm X80M钢的母材及环焊接头的微观组织和析出物的组织状态进行了分析。结果表明,母材组织以针状铁素体为主,含有少量的准多边形铁素体和M/A组织,析出物主要为Nb和Ti的碳氮化物。经过环焊后,热影响区的细晶区组织为多边形铁素体和粒状贝氏体,粗晶区组织为粒状贝氏体和针状铁素体,焊缝组织为准多边形铁素体和晶内针状铁素体。通过TEM观察,焊缝中薄膜状的M/A组织分布于板条贝氏体之间,析出物主要是AlN、TiN和Al_2O_3复合物。

The microstructure and precipitation of base metal and girth weld joint of the 33 mm X80 M steel were analyzed by using OM,SEM and TEM. The results indicate that the microstructure of base metal is mainly acicular ferrite,with a small amount of quasi-polygonal ferrite and M/A. The precipitates are mainly（ Nb,Ti） carbonitride. After girth welding,the microstructure of fine grain in heat affected zone consists of polygonal ferrite and granular bainite; the microstructure of coarse grain heat affected zone is consisted of granular bainite and acicular ferrite; the microstructure of weld zone consists of polygonal ferrite and intragranular acicular ferrite. By TEM observation,the thin film M/A of the weld zone is present between the lath bainite,and the precipitates are mainly consisted of AlN,TiN and Al_2O_3.