Study of hydrogen induced cracking in iron

Thesis/Dissertation · Tue Jan 01 00:00:00 EST 1985

OSTI ID:7046479

Armstrong, J H

The hydrogen assisted crack growth of Armco iron from cathodic charging was studied using continuous measurements of the modulus and internal friction. A Marx composite piezoelectric oscillator was used to measure resonant frequency and internal friction during the cathodic charging. Internal friction measured before and after cathodic charging was separated into dislocation and magnetic effects. The effects of charging time, vibratory strain amplitude and charging current density were studied. In all cases the modulus decreased continuously during cathodic charging. The internal friction increased rapidly during the early portion of cathodic charging and leveled off during the latter portion. Using a composite sample model (a cracked thin outer layer with a solid core), the change in modulus was found to be proportional to the quantity na/sup 3/..delta..d, where n is the crack density, a is the average crack radius and d is the depth of cracking. The kinetic behavior of both the internal friction and modulus change were found to be a two-part parallel exponential process. The rapid process was quite rapid and was found to be consistent with the initiation and growth of cracks due to the combination of hydrogen and carbon found at grain boundaries. The rapid increase in internal friction during the first process was attributed to the rapid plastic deformation from the initiation of the cracks.

• Research Organization: Denver Univ., CO (USA)
• OSTI ID: 7046479
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
IRON
CRACK PROPAGATION
HYDROGEN EMBRITTLEMENT
CATHODIC PROTECTION
DEFORMATION
GRAIN BOUNDARIES
INTERNAL FRICTION
MEASURING METHODS
YOUNG MODULUS
CORROSION PROTECTION
CRYSTAL STRUCTURE
ELEMENTS
EMBRITTLEMENT
FRICTION
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
TRANSITION ELEMENTS
360105* - Metals & Alloys- Corrosion & Erosion
360103 - Metals & Alloys- Mechanical Properties