Modified heat treatment for lower temperature improvement of the mechanical properties of two ultrahigh strength low alloy steels

Journal Article · Tue Jan 01 04:00:00 EST 1985 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02656715· OSTI ID:6303929

Tomita, Y; Okabayashi, K

In this paper, two commercial Japanese ultrahigh strength steels, 0.40 pct C-Ni-Cr-Mo (AISI 4340 type) and 0.40 pct C-Cr-Mo (AISI 4140 type), have been studied to determine the effect of the modified heat treatment, coupled above new heat treatment with repetitive heat treatment, on the mechanical properties from ambient temperature (287 K) to 123 K. The results obtained for various test temperatures have been compared with those for the new heat treatment reported previously. The microstructure consists of mixed areas of ultrafine grained martensite, within which is the refined blocky, highly dislocated structure, and the second phase lower bainite which appears in acicular form and partitions prior austenite grains. This newly developed heat treatment makes it possible to modify the new heat treatment reported previously so as to raise 0.2 pct proof stress to a higher level and keep notch toughness at the same level. The improvement in the mechanical properties is discussed in terms of metallographic observations and the modified law of mixtures.

• Research Organization: Department of Metallurgical Engineering, College of Engineering, University of Osaka Prefecture, Mozu-Umemachi, Sakai, Osaka
• OSTI ID: 6303929
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 15A:1; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101 -- Metals & Alloys-- Preparation & Fabrication
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
BAINITE
CARBON ADDITIONS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
CHROMIUM-NICKEL STEELS
CRYSTAL STRUCTURE
HEAT TREATMENTS
IRON ALLOYS
IRON BASE ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
METALLOGRAPHY
MICROSTRUCTURE
NICKEL ALLOYS
QUANTITY RATIO
QUENCHING
STEELS
TEMPERATURE EFFECTS