The hydrogen embrittlement of Ni-Cr-Fe alloys

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:296642

Symons, D M

It has been proposed that the stress corrosion cracking (SCC) of nickel-based alloys in low-temperature hydrogenated water is due to hydrogen embrittlement. The purpose of this work was to investigate the role of chromium on hydrogen embrittlement of Ni-Cr-Fe alloys and thus develop a better understanding of the low-temperature SCC phenomenon. The effect of chromium on the hydrogen embrittlement was examined using tensile tests followed by material evaluation via scanning electron microscopy and light optical microscopy. Four alloys were prepared with chromium contents ranging from 6 wt. percent to 35 wt. percent. In the noncharged condition, ductility, as measured by the percent elongation or reduction in area, increased as the alloy chromium content increased. Hydrogen appeared to have only minor effects on the mechanical properties of the low chromium alloys. The addition of hydrogen had a marked effect on the ductility of the higher chromium alloys. In the 26% chromium alloy, the elongation to failure was reduced from 53% to 14% with a change in fracture mode from ductile dimple to intergranular failure. A maximum in embrittlement was observed in the 26% Cr alloy. The maximum in embrittlement coincided with the minimum in stacking-fault energy. It is proposed that the increased hydrogen embrittlement in the high-chromium alloys is due to increased slip planarity caused by the low stacking-fault energy. Slip planarity did not appear to affect the fracture of the noncharged specimens.

• Research Organization: Bettis Atomic Power Lab., West Mifflin, PA (United States)
• Sponsoring Organization: USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
• DOE Contract Number: AC11-93PN38195
• OSTI ID: 296642
• Report Number(s): WAPD-T--3110; CONF-9605346--; ON: DE99000449
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHROMIUM
CHROMIUM ALLOYS
CRACK PROPAGATION
DUCTILITY
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
METALLURGICAL EFFECTS
MICROSTRUCTURE
NICKEL BASE ALLOYS
STRESS CORROSION
TENSILE PROPERTIES