科研之友
微信
新浪微博
Facebook
分享链接
摘要
This investigation demonstrates the effectiveness of using a nickel-based interlayer in preventing the formation of hard and soft zones during postweld heat treatment of Grade 22 ferritic steel weld clad with Grade 91 ferritic steel. Since carbon diffusion due to the activity gradient is responsible for the formation of the zones, a nickel-based interlayer (ENiCrFe-3) was introduced by welding to prevent carbon diffusion, thereby controlling the formation of hard and soft zones. Postweld heat treatment of weldments with 0.1-mm-thick interlayers was carried out at 1023 K for 1 and 15 h. Interfacial microstructure and microchemistry between Grade 22/ENiCrFe-3 and Grade 91/ENiCrFe-3 were investigated in detail using electron microprobe and transmission electron microscopy. Formation of a hard zone was not observed at the interface of the P91 steel and ENiCrFe-3 interlayer. However, presence of a zone of retained austenite (similar to 6 mu m in width) at the interface between Grade 22 and ENiCrFe-3 was confirmed. This zone did not show any systematic variation in width with postweld heat treatment schedule. Formation of retained austenite was understood based on nickel dilution across the interface during welding.
- 出版日期2010-4
