SYMPOSIA PAPER Published: 01 January 1992
STP17940S

Precipitation Evolution in HT-9 Steel Under Thermal Aging and Stress Rupture Conditions

Source

Precipitate development in two heats of HT-9 steels (84425 and 91354) during stressed and stress-free thermal aging treatments was studied. Stress-free thermal aging was conducted from 923 to 1033°K for 500 to 10 000 h while stress rupture conditions of 10.4 to 337 MPa stress at 811 to 1033°K for 60 to 17 754.8 h were utilized. Microdiffraction and energy dispersive X-ray spectroscopy techniques were used to analyze the precipitates. The carbide, M23C6, was the predominate precipitate phase in all conditions, with the exception of stressed specimens tested at 1033°K, where most of the M23C6 was replaced by chromium nitride (Cr2N). Cr2N was found only in stressed specimens at and above 977°K. The presence of Laves phase below 977°K produced a compositional variation in chromium in M23C6 and in the metal carbide phases of the MX type. Sigma phase was found only after long time testing at 811°K at a high stress level. The MX phases generally were found in both heats under all conditions. These phases were vanadium-rich in the stress rupture specimens, while titanium-rich in some of the stress-free thermally aged specimens.

Author Information

Pai, R-N
Materials Engineering Program, Department of Mechanical Engineering, Auburn University, AL
Wilcox, RC
Materials Engineering Program, Department of Mechanical Engineering, Auburn University, AL
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: E10
Pages: 1190–1205
DOI: 10.1520/STP17940S
ISBN-EB: 978-0-8031-5187-1
ISBN-13: 978-0-8031-1477-7