Microstructure and creep strength evolution in G115 steel during creep at 650 °C

Abstract

Microstructure and creep strength evolution in the ruptured 2.6 wt% W G115 specimens after creep tests were investigated under stresses of 120∼200 MPa at 650 °C. The growth of the lath during the creep tests was accompanied with the coarsening of second phase particles and the reduction of dislocation density. The tempered martensitic lath structure (TMLS) transformed into polygonal sub-grain structure when the pinning force due to the precipitates was lower than about 0.68 MPa. The Laves phase particles were irregular during the short-term creep and grew to be equiaxed shape after long-term creep.

Keywords

• long-term creep
• 650 °C
• microstructure evolution
• laves phase
• G115 steel