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Titolo:
Strengthening mechanisms of creep resistant tempered martensitic steel
Autore:
Maruyama, K; Sawada, K; Koike, J;
Indirizzi:
Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Aoba Ku, Sendai, Miyagi 9808579,Japan Tohoku Univ Sendai Miyagi Japan 9808579 Ku, Sendai, Miyagi 9808579,Japan Natl Res Inst Met, Tsukuba, Ibaraki 3050047, Japan Natl Res Inst Met Tsukuba Ibaraki Japan 3050047 a, Ibaraki 3050047, Japan
Titolo Testata:
ISIJ INTERNATIONAL
fascicolo: 6, volume: 41, anno: 2001,
pagine: 641 - 653
SICI:
0915-1559(2001)41:6<641:SMOCRT>2.0.ZU;2-C
Fonte:
ISI
Lingua:
ENG
Soggetto:
LONG-TERM CREEP; HIGH-TEMPERATURE; FERRITIC STEELS; MOD.9CR-1MO STEEL; LIFE ASSESSMENT; CHROMIUM STEEL; LATH STRUCTURE; SUBGRAIN SIZE; MICROSTRUCTURE; STABILITY;
Keywords:
steel for elevated temperature service; creep; strengthening mechanism; alloy design; microstructure; microstructural degradation;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
Citazioni:
77
Recensione:
Indirizzi per estratti:
Indirizzo: Maruyama, K Tohoku Univ, Grad Sch Engn, Dept Mat Sci, Aoba Ku, Aobayama, Sendai, Miyagi 9808579, Japan Tohoku Univ Aobayama Sendai Miyagi Japan 9808579 808579, Japan
Citazione:
K. Maruyama et al., "Strengthening mechanisms of creep resistant tempered martensitic steel", ISIJ INT, 41(6), 2001, pp. 641-653

Abstract

The creep deformation resistance and rupture life of high Cr ferritic steel with a tempered martensitic lath structure are critically reviewed on thebasis of experimental data. Special attention is directed to the followingthree subjects: creep mechanism of the ferritic steel, its alloy design for further strengthening, and loss of its creep rupture strength after long-term use. The high Cr ferritic steel is characterized by its fine subgrain structurewith a high density of free dislocations within the subgrains. The dislocation substructure is the most densely distributed obstacle to dislocation motion in the steel. Its recovery controls creep rate and rupture life at elevated temperatures. Improvement of creep strength of the steel requires a fine subgrain structure with a high density of free dislocations. A sufficient number of pinning particles (MX particles in subgrain interior and M23C6 particles on sub-boundaries) are necessary to cancel a large driving force for recovery due to the high dislocation density. Coarsening and agglomeration of the pinning particles have to be delayed by an appropriate alloy design of the steel. Creep rupture strength of the high Cr ferritic steel decreases quickly after long-term use. A significant improvement of creep rupture strength can be achieved if we can prevent the loss of rupture strength. In the steel tempered at high temperature, enhanced recovery of the subgrain structure along grain boundaries is the cause of the premature failure and the consequentloss of rupture strength. However, the scenario is not always applicable. Further studies are needed to solve this important problem of high Cr ferritic steel. MX particles are necessary to retain a fine subgrain structure and to achieve the excellent creep strength of the high Cr ferritic steel. Strengthening mechanism of the MX particles is another important problem left unsolved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 22/09/20 alle ore 22:25:35