Microstructure of a Creep-Resistant 10 Pct Chromium Steel Containing 250 ppm Boron
Journal article, 2011

The microstructure of a trial martensitic chromium steel containing a high content of boron (250 ppm) was characterized in detail in the as-tempered and aged conditions. This steel has a similar composition and heat treatment as the TAF steel that still is unsurpassed in creep strength among all 9 to 12 pct chromium steels. Characterization was performed by using scanning electron microscopy, energy-filtered transmission electron microscopy, secondary ion mass spectroscopy, and atom probe tomography. Focus was placed on investigating different types of precipitates that play a key role in improving the creep resistance of these steels. The low tempering temperature of 963 K (690 A degrees C) is enough for the precipitation of the full volume fraction of both MX and M23C6. A high boron content, more than 1 at. pct, was found in M23C6 precipitates and they grow slowly during aging. The high boron level in the steel results in metal borides rather than BN with the approximate formula (Mo0.66Cr0.34)(2)(Fe0.75V0.25)B-2. Two families of MX precipitates were found, one at lath boundaries about 35 nm in size and one dense inside the laths, only 5 to 15 nm in size.

Author

Ardeshir Golpayegani

Chalmers, Applied Physics, Microscopy and Microanalysis

Fang Liu

Chalmers, Applied Physics, Microscopy and Microanalysis

Henrik Svensson

Chalmers, Applied Physics, Microscopy and Microanalysis

MARCUS ANDERSSON

Chalmers, Applied Physics, Microscopy and Microanalysis

Hans-Olof Andrén

Chalmers, Applied Physics, Microscopy and Microanalysis

Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science

1073-5623 (ISSN)

Vol. 42 4 940-951

Areas of Advance

Energy

Materials Science

Subject Categories

Other Materials Engineering

DOI

10.1007/s11661-010-0555-1

More information

Created

10/7/2017