Microstructural basis of alloy design for high-strength, tough structural steels

Conference · Tue Sep 01 04:00:00 EDT 1981

OSTI ID:6880246

Thomas, G; Sarikaya, M; Smith, G D.W.; Barnard, S J

Optimum mechanical properties may be obtained in medium carbon steels with microstructures consisting of dislocated lath martensites in which laths are surrounded by films of retained austenite. Direct studies of the chemical composition of the retained austenite phase, using the experimental technique of atom probe microanalysis, show that the austenite is substantially enriched in carbon and a large peak in carbon concentration is found at the austenite/martensite interface even in the as-quenched condition. Carbon partitioning depleting the martensite matrix must occur during transformation. Although the enrichment of austenite by carbon provides some chemical stability, mechanical stabilization must also be a major factor. The austenite may be destabilized by tempering or by plastic deformation. The relationship between these results and the strength and fracture toughness properties of a range of Fe-Cr-0.3C steels containing Mn or Ni are presented, together with recent results of in-situ studies of fracture in a high voltage electron microscope. 6 figures, 3 tables.

• Research Organization: Lawrence Berkeley Lab., CA (USA); Oxford Univ. (UK). Dept. of Metallurgy and Science of Materials
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6880246
• Report Number(s): LBL-13048; CONF-8109190-1; ON: DE83003664
• 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
CARBON ADDITIONS
CARBON STEELS
CRYSTAL STRUCTURE
FRACTURE PROPERTIES
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
MICROSTRUCTURE
OPTIMIZATION
STEELS
TEMPERING