Dissolution kinetics of {delta} phase and its influence on the notch sensitivity of Inconel 718

Journal Article · Thu Mar 15 04:00:00 EDT 2007 · Materials Characterization

OSTI ID:21003534

Dayong, Cai ^[1]; Weihong, Zhang ^[1]; Pulin, Nie ^[1]; Wenchang, Liu ^[1]; Mei, Yao ^[1]

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1. State key Laboratory of Metastable Materials Science and Technology, Yanshan University, 066004, Qinhuangdao (China)

The dissolution kinetics of {delta} phase in Inconel 718 at 980 deg. C, 1000 deg. C and 1020 deg. C and its influence on high temperature notch sensitivity have been studied using a quantitative X-ray diffraction (XRD) method and high temperature stress rupture life tests of notched specimens. The amount of {delta} phase decreases gradually during holding time at 980 deg. C, 1000 deg. C and 1020 deg. C. The {delta} phase will be fully dissolved in the austenitic matrix at 1020 deg. C for more than 2 h. A certain amount of {delta} phase still exists after holding at 980 deg. C and 1000 deg. C for times up to 6 h; the amount remaining are 3 wt.% and 0.6 wt.%, respectively. The dissolution rate remains at a high level at the beginning, and then decreases gradually with an increase of holding time. A dynamic equilibrium state can be approached after holding at 980 deg. C for more than 30 min and at 1000 deg. C for more than 2 h. The alloy with {delta} phase amounts higher than 0.62 wt.% does not exhibit notch sensitivity, whereas serious notch sensitivity exists if the concentration is below 0.43 wt.%.

• OSTI ID: 21003534
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 3 Vol. 58; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AUSTENITIC STEELS
DISSOLUTION
INCONEL 718
NOTCHES
RUPTURES
SENSITIVITY
THERMAL STRESSES
X-RAY DIFFRACTION