Response of ferritic steels to nonsteady loading at elevated temperatures

Conference · Sun Apr 01 04:00:00 EST 1984

OSTI ID:6695064

Swindeman, R W

High-temperature operating experience is lacking in pressure vessel materials that have strength levels above 586 MPa. Because of their tendency toward strain softening, we have been concerned about their behavior under nonsteady loading. Testing was undertaken to explore the extent of softening produced by monotonic and cyclic strains. The specific materials included bainitic 2 1/4Cr-1Mo steel, a micro-alloyed version of 2 1/4Cr-1Mo steel, a micro-alloyed version of 2 1/4Cr-1Mo steel containing vanadium, titanium, and boron, and a martensitic 9Cr-1Mo-V-Nb steel. Tests included tensile, creep, variable stress creep, relaxation, strain cycling, stress cycling, and non-isothermal creep ratchetting experiments. We found that these steels had very low uniform elongation and exhibited small strains to the onset of tertiary creep compared to annealed 2 1/4Cr-1Mo steel. Repeated relaxation test data also indicated a limited capacity for strain hardening. Reversal strains produced softening. The degree of softening increased with increased initial strength level. We concluded that the high strength bainitic and martensitic steels should perform well when used under conditions where severe cyclic operation does not occur.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6695064
• Report Number(s): CONF-840647-23-Draft; ON: DE84014280
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
CONTAINERS
CREEP
FATIGUE
HIGH TEMPERATURE
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS TESTING
MECHANICAL PROPERTIES
NIOBIUM ADDITIONS
NIOBIUM ALLOYS
PRESSURE VESSELS
RELAXATION
STEELS
STRAIN SOFTENING
STRESS RELAXATION
TEMPERATURE DEPENDENCE
TENSILE PROPERTIES
TESTING
TITANIUM ADDITIONS
TITANIUM ALLOYS
VANADIUM ADDITIONS
VANADIUM ALLOYS