J Mater Sci Technol ›› 2003, Vol. 19 ›› Issue (02): 126-128.

• Research Articles • Previous Articles     Next Articles

Microstructural Evolution of 2.25Cr-1.6W-V-Nb Heat Resistant Steel during Creep

Lihui ZHU, Xueming MA   

  1. School of Materials Science and Engineering, Shanghai University, Shanghai 200072, China...
  • Received:1900-01-01 Revised:1900-01-01 Online:2003-03-28 Published:2009-10-10
  • Contact: Lihui ZHU

Abstract: 2.25Cr-1.6W-V-Nb developed in Japan, is a low alloy heat resistant steel with good comprehensive properties. Influence of long term creep at elevated temperature on the structure of 2.25Cr-1.6W-V-Nb steel was studied in this paper, and the micromechanism of creep strength degradation was elucidated, too. Both TEM observation and thermodynamic calculation reveal that during creep the transformation occurs from M7C3 and M23C6 to M6C, which can be cavity nucleation sites. Besides, creep at 600℃ also leads to the decrease of dislocation density, the coarsening and coalescence of M23C6, the nucleation of cavities and development of cracks. The strength decrease of 2.25Cr-1.6W-V-Nb steel after long term creep is related to the decrease of dislocation hardening, precipitation hardening, solution hardening, the nucleation of cavities and development of cracks.

Key words: Heat resistant steel, Creep, Microstructural evolution