The use of microstructure control to toughen ferritic steels for cryogenic use. II. Fe--Mn steels

Conference · Wed Dec 01 04:00:00 EST 1976

OSTI ID:7144113

Hwang, S K; Morris, Jr, J W

The research reported here addresses the microstructural modification of ferritic Fe-Mn alloys to improve low temperature properties. The alloys Fe-12Mn-0.2Ti and Fe-8Mn-0.2Ti were specifically studied. In the as-quenched condition the alloys have ductile-brittle transition temperatures near -50/sup 0/C and room temperature respectively. The brittleness of Fe-12Mn is due to the intrusion of an intergranular fracture mode; that of Fe-8Mn is due to quasi-cleavage. The transition temperature of the 12Mn alloy may be suppressed by annealing in the two-phase (..cap alpha.. + ..gamma..) range to introduce a distribution of austenite or by grain refinement through deformation processing. In the latter case an excellent combination of strength and toughness is obtained at liquid nitrogen temperature. The 12Mn alloy may not be thermally processed to fine grain size because of the malevolent influence of the epsilon-martensite phase present in the as-quenched structure. No such phase is present in the 8Mn alloy. This alloy may be thermally processed to ultrafine grain size with a concommitant marked improvement in low temperature mechanical properties.

• Research Organization: California Univ., Berkeley (USA). Lawrence Berkeley Lab.
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 7144113
• Report Number(s): LBL-5782; CONF-761085-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
CRYSTAL STRUCTURE
DUCTILITY
GRAIN SIZE
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
MICROSTRUCTURE
PHASE TRANSFORMATIONS
SIZE
TENSILE PROPERTIES
TITANIUM ALLOYS