Propagation of stress corrosion cracks in alpha-brasses
- Univ. of Illinois, Urbana-Champaign, IL (United States)
Transgranular and intergranular stress corrosion cracks were investigated in alpha-brasses in a tarnishing ammoniacal solution. Surface observation indicated that the transgranular cracks propagated discontinuously by the sudden appearance of a fine crack extending several microns ahead of the previous crack tip, often associated with the detection of a discrete acoustic emission (AE). By periodically increasing the deflection, crack front markings were produced on the resulting fracture surfaces, showing that the discontinuous propagation of the crack trace was representative of the subsurface cracking. The intergranular crack trace appeared to propagate continuously at a relatively blunt crack tip and was not associated with discrete AE. Under load pulsing tests with a time between pulses, Δt greater than or equal to 3 s, the transgranular fracture surfaces always exhibited crack front markings which corresponded with the applied pulses. The spacing between crack front markings, Δx, decreased linearly with Δt. With Δt less than or equal to 1.5 s, the crack front markings were in a one-to-one correspondence with applied pulses only at relatively long crack lengths. In this case, Δx = Δx* which approached a limiting value of 1 μm. No crack front markings were observed on intergranular fracture surfaces produced during these tests. It is concluded that transgranular cracking occurs by discontinuous mechanical fracture of an embrittled region around the crack tip, while intergranular cracking results from a different mechanism with cracking occurring via the film-rupture mechanism.
- Research Organization:
- Univ. of Illinois at Urbana-Champaign, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC02-76ER01198
- OSTI ID:
- 7084372
- Report Number(s):
- DOE/ER/01198-1328
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BRASS-ALPHA
STRESS CORROSION
AMMONIA
AQUEOUS SOLUTIONS
CRACKS
DYNAMIC LOADS
INTERGRANULAR CORROSION
PULSES
SOUND WAVES
SURFACES
ALLOYS
BRASS
CHEMICAL REACTIONS
COPPER ALLOYS
COPPER BASE ALLOYS
CORROSION
DISPERSIONS
HYDRIDES
HYDROGEN COMPOUNDS
MIXTURES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
SOLUTIONS
ZINC ALLOYS
360105* - Metals & Alloys- Corrosion & Erosion