Subgrain refinement strengthening. Annual report, October 1, 1974--September 30, 1975
Investigations were conducted to develop fine subgrains in selected ferritic and austenitic alloys as a possible means of enhancing the creep resistance of such materials. The model systems selected for testing during the report period include an austenitic stainless steel (type 304) and a ferritic stainless steel (26 chromium, 1 molybdenum). Results of tests indicate the strong effect that subgrain refinement may have on the high temperature properties of materials when subgrain strengthening dominates the deformation process. Since subgrain formation is a dominant structural feature of iron base alloys after warm deformation it is clearly worth-while to quantify the possible influence of subgrain size on the creep rate of austenitic and ferritic stainless steels. It was found that the flow stress, sigma, is a function of the subgrain size, lambda, following the relation sigma varies as lambda/sup -0/./sup 35/. It was possible to predict that 304 stainless steel can be increased in strength by a factor of 2.7 over the normally expected strength at 650/sup 0/C and epsilon = 10/sup -10/s/sup -1/ (i.e., a one year rupture life) if stable subgrains 0.2 ..mu..m in size can be developed. It is postulated that the dislocations within the subgrain boundary in 26 Cr--1 Mo steel take on a more perfect ordered array with strain; it is then suggested that a well ordered array may be a poor barrier to plastic flow at warm temperature (where dislocation climb is rate controlling) but is a good barrier at low temperature (where dislocations must break through the subgrain boundary barrier).
- Research Organization:
- Stanford Univ., Calif. (USA). Dept. of Materials Science and Engineering
- OSTI ID:
- 7338024
- Report Number(s):
- SU-326P38X5
- Country of Publication:
- United States
- Language:
- English
Similar Records
Subgrain refinement strengthening. Third quarterly progress report, April 1, 1975-June 30, 1975
Variation in the spacing of dislocations in subgrain boundaries with creep strain in Type 304 stainless steel
Related Subjects
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-MOLYBDENUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
GRAIN SIZE
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
LINE DEFECTS
MECHANICAL PROPERTIES
MICROSTRUCTURE
NICKEL ALLOYS
ORDER PARAMETERS
SIZE
STAINLESS STEEL-304
STAINLESS STEELS
STEELS
STRAINS
STRESSES
YIELD STRENGTH