Inhibition of hydrogen embrittlement in high strength steel. Technical report. [AISI 4340]

Technical Report · Tue Feb 01 04:00:00 EST 1977

OSTI ID:7255156

Kortovich, C S

The addition of rare earth gettering agents to trap hydrogen was evaluated as a method of reducing the embrittlement problems in steel cathodically charged with hydrogen. Additions of lanthanum and cerium made to AISI 4340 steel were used in the 0.03--0.17 weight percent range. Mechanical property results were comparable for both elements and indicated that, while some degradation in property levels occurred, particularly at the high rare earth content, most of the aircraft quality specification minimums for 4340 high strength steel were attained. An important exception was the Charpy impact strength, which was approximately 15% below the minimum. Property loss was attributed to the formation of continuous rare earth oxide inclusions at prior austenite grain boundaries. Delayed failure test results indicated substantial improvements in hydrogen embrittlement resistance for high rare earth content (>0.15 weight percent) steels. This was manifested in terms of increased time to crack initiationn (incubation time), increased failure time, higher values for the lower critical stress intensity and lower crack growth rates compared to baseline 4340 or the low rare earth modifications. Cerium was slightly superior to lanthanum only in terms of resulting in a higher level for the lower critical stress intensity.

• Research Organization: TRW, Inc., Cleveland, OH (USA)
• OSTI ID: 7255156
• Report Number(s): AD-A-037355; TRW-ER-7814-2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CERIUM ADDITIONS
CERIUM ALLOYS
CRYOGENIC FLUIDS
ELEMENTS
EMBRITTLEMENT
FAILURES
FLUIDS
GETTERS
HYDROGEN
IMPACT STRENGTH
IRON ALLOYS
IRON BASE ALLOYS
LANTHANUM ADDITIONS
LANTHANUM ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
NONMETALS
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
STEELS