Metallographic examinations of Type 304 stainless steel (heat 9T2796) tested in high-temperature uniaxial and multiaxial experiments
The results obtained from a number of metallographic examinations of Type 304 stainless steel specimens were compiled. Samples were obtained from uniaxial and multiaxial tests covering a very broad span of temperatures and times. Special emphasis was on the identification of failure modes, cracking patterns, grain distortion, and grain-boundary microstructures. Uniaxial specimens exhibited the following sequence of failure modes with increasing temperature and time: ductile plastic tearing, ductile plastic shear, wedge cracking, and microvoid cracking. Over most of the temperature range examined (482 to 871/sup 0/C), M/sub 23/C/sub 6/ precipitated on grain boundaries at long times. Sigma phase and possibly ferrite were often present in the stressed areas at temperatures as low as 482/sup 0/C (900/sup 0/F). These metallurgical features promoted a severe loss in creep ductility at long times and low temperatures. Most multiaxial tests were performed under conditions that promoted wedge cracking. Stress gradients also favored surface crack initiation rather than bulk damage. Testing times for multiaxial tests were less than 10,000 h; hence, there was insufficient time for the development of embrittling features such as microvoids, sigma, and ferrite. Long-time multiaxial tests to failure are recommended.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5112482
- Report Number(s):
- ORNL-6013; ON: DE84010637
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
STAINLESS STEEL-304
MECHANICAL TESTS
MICROSTRUCTURE
CRACK PROPAGATION
CREEP
FAILURE MODE ANALYSIS
FATIGUE
METALLOGRAPHY
ALLOYS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
CRYSTAL STRUCTURE
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MATERIALS TESTING
MECHANICAL PROPERTIES
NICKEL ALLOYS
STAINLESS STEELS
STEELS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
TESTING
360102* - Metals & Alloys- Structure & Phase Studies