Heat-treatment, microstructure and mechanical properties of experimental high strength Fe--4Cr--0. 4C steels

Conference · Mon Dec 01 04:00:00 EST 1975

OSTI ID:7273942

Narasimha Rao, B V; Miller, R W; Thomas, G

The treatments involve high temperature (1100/sup 0/C) austenitizing during the first solution treatment followed by either interrupted quenching (Ms-Mf range) or isothermal transformation to produce lower bainite. Finally, the steels are given a 900/sup 0/C grain refinement treatment. Lower bainite was obtained by isothermally transforming austenite just above the Ms temperature. Tempering after the martensitic and bainitic treatments was also done in an attempt to improve the toughness of the material. The strength and toughness properties of as-quenched martensitic structures are somewhat superior while these properties of lower bainitic structures are comparable to those of a plain 0.4C steel. The properties of the nearly 100 percent bainite structure were unaffected by the cooling rate from the transformation temperature. Elimination of intergranular cracking produced toughness properties in quenched and tempered martensites which are far superior to those of lower bainite at the same strength level. It has also been shown that the toughness properties of as-quenched double-treated steels are superior to single treated steels. The chromium appeared to have a strong influence on the nature and morphology of carbides, as the bainitic as well as the martensitic structures showed marked temper resistance in the tempering range 200 to 500/sup 0/C.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7273942
• Report Number(s): LBL-3982; CONF-760537-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
AUSTENITE
BAINITE
CARBON ADDITIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CRYSTAL STRUCTURE
DUCTILITY
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
PHYSICAL PROPERTIES
QUENCHING
STEELS
TENSILE PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
VERY HIGH TEMPERATURE