Structure-property relations and the design of Fe-4Cr-C base structural steels for high strength and toughness
Some design guidelines for improving strength-toughness combinations in medium carbon structural steels are critically reviewed. From this, quaternary alloy development based on Fe/Cr/C steels with Mn or Ni additions for improved properties is described. Transmission electron microscopy and X-ray analysis reveal increasing amounts of retained austenite in these alloys with Mn content up to 2 wt % and Ni additions at 5 wt % after quenching from 1100/sup 0/C. A corresponding improvement in toughness properties is also found. Grain refining results in a further increase in the amount of retained austenite. In addition, the excellent combinations of strength and toughness in these quaternary alloys are attributed to the production of dislocated lath martensite from a homogeneous austenite phase free from undissolved alloy carbides. The question of thermal instability of retained austenite following tempering is considered in detail and it is shown that the decomposition of retained austenite is closely related to the ease of nucleation and growth of cementite. Thus, graphitizing alloys elements such as Ni are beneficial in postponing the decomposition of retained austenite.
- Research Organization:
- Univ. of California, Berkeley
- OSTI ID:
- 5418861
- Journal Information:
- Metall. Trans., A; (United States), Vol. 11:3; Conference: Symposium on precipitation processes in structural steels, Denver, CO, USA, 27 Feb 1978
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CHROMIUM STEELS
FRACTURE PROPERTIES
MICROSTRUCTURE
NICKEL-CHROMIUM STEELS
CHROMIUM ALLOYS
IRON BASE ALLOYS
MANGANESE ALLOYS
AUSTENITE
CARBON ADDITIONS
CHEMICAL COMPOSITION
MECHANICAL PROPERTIES
QUENCHING
STABILITY
TRANSMISSION ELECTRON MICROSCOPY
ALLOYS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
IRON ALLOYS
MICROSCOPY
NICKEL ALLOYS
NICKEL STEELS
STEELS
360102* - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties