The effect of hot working on structure and strength of a precipitation strengthened austenitic stainless steel

Journal Article · Wed Feb 01 04:00:00 EST 1984 · Metall. Trans., A; (United States)

DOI:https://doi.org/10.1007/BF02645121· OSTI ID:6795044

Mataya, M C; Carr, M J; Krauss, G

The development of microstructure and strength during forging a ..gamma..' strengthened austenitic stainless steel, JBK-75, was investigated. The specimens were deformed in a strain range of 0.16 to 1.0, from 800 /sup 0/C to 1080 /sup 0/C at approximate strain rates of 2 (press forging) and 2 X 10/sup 3/ S/sup -1/ (high energy rate forging). Mechanical properties were determined by tensile testing as-forged and forged and aged specimens. The alloy exhibited a wide variety of structures and properties within the range of forging parameters studied. Deformation at the higher strain rate via high energy rate forging resulted in unrecovered substructures and high strengths at low forging temperatures, and static recrystallization and low strengths at high temperatures. In contrast, however, deformation at the lower strain rate via press forging resulted in retention of the well developed subgrain structure and associated high strength produced at high forging temperatures and strains. At lower temperatures and strains during press forging a subgrain structure formed preferentially at high angle grain boundaries, apparently by a creep-type deformation mechanism. Dynamic recrystallization was not an important restoration mechanism for any of the forging conditions. The results are interpreted on the basis of stacking fault energy and the accumulation of strain energy during hot working. The significance of microstructural differences for equivalent deformation conditions (iso-Z, where Z is the Zener-Holloman parameter) is discussed in relation to the utilization of Z for predicting hot work structures and strengths. Aging showed that ..gamma..' precipitation is not affected by substructure and that the strengthening contributions were independent and additive. Applications for these findings are discussed in terms of process design criteria.

• Research Organization: Rockwell International Energy Systems Group, Golden, CO
• OSTI ID: 6795044
• Journal Information: Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 15A:2; ISSN MTTAB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
360102 -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
AUSTENITIC STEELS
CHROMIUM ALLOYS
CORROSION RESISTANT ALLOYS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DEFORMATION
FABRICATION
GRAIN BOUNDARIES
HARDENING
HOT WORKING
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSTRUCTURE
MORPHOLOGICAL CHANGES
PHASE TRANSFORMATIONS
PRECIPITATION HARDENING
STACKING FAULTS
STAINLESS STEELS
STEELS
STRAIN RATE
TEMPERATURE EFFECTS