Creep ductility of iron at very low strain rates: The effects of sulfur

Conference · Thu Dec 31 04:00:00 EST 1992

OSTI ID:10164657

George, E P ^[1]; Sklenicka, V ^[2]; Pope, D P ^[3]

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1. Oak Ridge National Lab., TN (United States)
2. Ceskoslovenska Akademie Ved, Brno (Czech Republic). Ustav Fyzikalni Metalurgie
3. Pennsylvania Univ., Philadelphia, PA (United States). Dept. of Materials Science and Engineering

Creep ductility of iron containing sulfur (200, 20 and 1 wt ppm) was measured as a function of stress and temperature in constant-stress creep tests at 673, 773, 873, and 973 K in H{sub 2}. Failure times ranged from one minute to one year. Creep strengths of the 20 and 1 ppm S material were similar, but the 200 ppm S material was stronger than the other two, especially at very low strain rates. Also, at a given strain rate, a ductility minimum is seen at 873 K, the depth of which increases with sulfur content and is result of increased intergranular failure. The strain rate (or reciprocal of failure time) at which the failure mode changes from transgranular to intergranular fracture decreases with decreasing sulfur content. Intergranular creep cavities were found to nucleate on sulfides in the high-sulfur material, and on unidentified small particles{emdash}presumably oxides{emdash}in the other two. It is concluded that creep cavities nucleate easily on FeS particles but that nucleation on oxide particles is more difficult, especially when the interfacial sulfur content is low. However, it is not possible to totally prevent cavity nucleation even after reducing the sulfur level to 1 ppm. 17 refs, 7 figs, 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States); Electric Power Research Inst., Palo Alto, CA (United States); National Science Foundation, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 10164657
• Report Number(s): CONF-9211117--8; ON: DE93015490; CNN: Grant DMR91-20668
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103
CAVITIES
CREEP
DUCTILITY
FAILURE MODE ANALYSIS
FRACTOGRAPHY
FRACTURES
IRON
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
NUCLEATION
STRAIN RATE
SULFUR