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Title: Microstructural evolution in a ferritic-martensitic stainless steel and its relation to high-temperature deformation and rupture models

The ferritic-martensitic stainless steel HT-9 exhibits an anomalously high creep strength in comparison to its high-temperature flow strength from tensile tests performed at moderate rates. A constitutive relation describing its high-temperature tensile behavior over a wide range of conditions has been developed. When applied to creep conditions the model predicts deformation rates orders of magnitude higher than observed. To account for the observed creep strength, a fine distribution of precipitates is postulated to evolve over time during creep. The precipitate density is calculated at each temperature and stress to give the observed creep rate. The apparent precipitation kinetics thereby extracted from this analysis is used in a model for the rupture-time kinetics that compares favorably with observation. Properly austenitized and tempered material was aged over times comparable to creep conditions, and in a way consistent with the precipitation kinetics from the model. Microstructural observations support the postulates and results of the model system. 16 refs., 10 figs.
Authors:
; ;
Publication Date:
OSTI Identifier:
6412280
Report Number(s):
CONF-910202-2
ON: DE91006471
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Annual meeting and exhibition of the Minerals, Metals and Materials Society, New Orleans, LA (USA), 17-21 Feb 1991
Research Org:
Argonne National Lab., IL (USA)
Sponsoring Org:
DOE/NE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; STAINLESS STEELS; CREEP; TENSILE PROPERTIES; DEFORMATION; KINETICS; MICROSTRUCTURE; PRECIPITATION; RUPTURES; ULTIMATE STRENGTH; ALLOYS; CRYSTAL STRUCTURE; FAILURES; HIGH ALLOY STEELS; IRON ALLOYS; IRON BASE ALLOYS; MECHANICAL PROPERTIES; SEPARATION PROCESSES; STEELS 360103* -- Metals & Alloys-- Mechanical Properties; 360102 -- Metals & Alloys-- Structure & Phase Studies