Role of microstructure on hydrogen-assisted cracking in high strength steels. [9Ni-4Co steel and 4140 steel]
- Carnegie-Mellon Univ., Pittsburgh, PA (USA)
The effect of precharged hydrogen on crack initiation and propagation has been studied in bainite and martensite in both a 9Ni-4Co 0.35% steel and a 4140 steel. Tests were conducted in both microstructures at equal yield strength and at equal toughness to evaluate the importance of these parameters. An acoustic emission technique was used to detect crack initiation in cathodically-charged four-point bend specimens of varying notch root radii. In general embrittlement increased at higher yield strengths in both microstructures. Crack growth rate was studied using precracked double-cantilever-beam specimens. Tempered martensite displayed better resistance to embrittlement than lower bainite at 1300 MPa yield strength in the 9Ni-4Co steel. However, lower bainite performed better than tempered martensite at other strength levels in these steels. Hydrogen permeation tests and transmission electron microscopy were used as measures of hydrogen trapping behavior.
- OSTI ID:
- 5450855
- Report Number(s):
- CONF-840909-; CODEN: TMPSA
- Journal Information:
- TMS (The Metallurgical Society) Paper Selection; (USA), Vol. 56; Conference: TMS-AIME fall meeting, Detroit, MI (USA), 16-20 Sep 1984; ISSN 0197-1689
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BAINITE
HYDROGEN EMBRITTLEMENT
MICROSTRUCTURE
MARTENSITE
STEELS
ACOUSTIC EMISSION TESTING
COBALT ALLOYS
CRACK PROPAGATION
CRACKS
FRACTURE PROPERTIES
HYDROGEN
NICKEL ALLOYS
PERMEABILITY
TRANSMISSION ELECTRON MICROSCOPY
YIELD STRENGTH
ACOUSTIC TESTING
ALLOYS
CARBON ADDITIONS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ELEMENTS
EMBRITTLEMENT
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS TESTING
MECHANICAL PROPERTIES
MICROSCOPY
NONDESTRUCTIVE TESTING
NONMETALS
TESTING
360102* - Metals & Alloys- Structure & Phase Studies
360103 - Metals & Alloys- Mechanical Properties