On the origin of the superior long-term creep resistance of a 10% Cr steel

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:713

Article

Mishnev, R.¹  Dudova, N.¹  Kaibyshev, R.¹ 

[1] Belgorod State Univ, Belgorod 308015, Russia

关键词: Martensite;    Steel;    Creep;    Electron microscopy;    Precipitation;    Coarsening;   

DOI  :  10.1016/j.msea.2017.12.066

来源: Elsevier

【 摘 要 】

A low-nitrogen 10% Cr martensitic steel containing 3% Co and 0.008% B was shown to exhibit an extremely long creep rupture time of similar to 4.10(4) h under an applied stress of 120 MPa at 650 degrees C. The creep behavior and evolution of lath martensite structure and precipitates during creep at these conditions were studied. The main feature of the microstructure under long-term creep is retention of the lath structure until rupture. The following micro structural factors affecting the superior creep resistance were analyzed: (1) alloying by (W + Mo) elements; (2) particles of M23C6 and Laves phases; (3) homogeneously distributed M(C,N) carbonitrides. It was revealed that nanoscale M23C6 carbides and M(C,N) carbonitrides compensated the negative effects of W depletion from the solid solution and extensive coarsening of the Laves phase particles. M23C6 carbides demonstrate a high coarsening resistance under creep conditions and exert a high Zener drag pressure before rupture because of the coherency of their interfaces. The strain-induced transformation of a portion of the precipitated V-rich M(C,N) carbonitrides to the Z-phase does not affect the creep strength because the Z-phase particles are nanoscale and negligible in quantity.

【 授权许可】

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