Effects of aluminum content on the mechanical properties of a 9Cr-0.5Mo-1.8W steel

Journal Article · Thu May 01 04:00:00 EDT 1997 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/s11661-997-0284-2· OSTI ID:509178

Naoi, H; Ohgami, M; Liu, X ^[1]; Fujita, T ^[2]

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1. Nippon Steel Corp., Chiba (Japan). Steel Research Labs.
2. Univ. of Tokyo (Japan)

The effects of aluminum content on mechanical properties of a 9Cr-0.5Mo-1.8W steel have been investigated. It was found that aluminum addition had a beneficial effect on toughness, but significantly reduced the creep resistance of the steel, especially on the long-term side. Examination of the microstructure and precipitation characteristics revealed that almost all of the aluminum added existed as AlN-type nitrides after normalizing and tempering. The undissolved AlN in high aluminum steels resulted in a dramatic refinement of prior austenite grains, which contributed to the improvement of toughness and was also partially responsible for the decreased creep rupture strength. The formation of AlN suppressed the precipitation of VN-type nitride; AlN also provided formation sites for Nb(C, N) and M{sub 23}C{sub 6} type, which had an equivalent effect to the coalescence of these precipitates on AlN, resulting in the reduction of precipitate density and, therefore, decreased creep resistance.

• Sponsoring Organization: USDOE
• OSTI ID: 509178
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 5 Vol. 28; ISSN 1073-5623; ISSN MMTAEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ADDITIONS
CHROMIUM STEELS
CONCENTRATION RATIO
CREEP
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
MICROSTRUCTURE
MOLYBDENUM
PRECIPITATION
TENSILE PROPERTIES
TUNGSTEN