Atmospheric stress corrosion cracking of a superplastic 7475 aluminum alloy

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science

DOI:https://doi.org/10.1007/BF02652355· OSTI ID:382513

Tsai, T C; Chuang, T H ^[1]

---

1. National Taiwan Univ., Taipei (Taiwan, Province of China). Inst. of Materials Science and Engineering

The influence of different heat treatments upon the atmospheric stress corrosion cracking (SCC) of fine-grained 7475 Al-alloy plates has been investigated. The small size of the matrix precipitates and grain-boundary precipitates (GBPs) was found to be the main cause of atmospheric SCC susceptibility. Increasing the size of the matrix precipitates and GBPs by increasing the degree of aging could improve the atmospheric SCC resistance. The size of the matrix precipitates was the major factor affecting the atmospheric SCC resistance when GBPs were larger than a critical size that could nucleate hydrogen bubbles. However, if the size of the GBPs was smaller than this critical size, the improvement of atmospheric SCC resistance due to grain refinement, resulting from a more homogeneous slip mode, could not be obtained because hydrogen embrittlement became serious. By measuring the electrical conductivity, the influence of matrix precipitates, but not that of GBPs, on SCC susceptibility could be obtained. Retrogression and reaging (RRA) treatment could effectively improve the atmospheric SCC resistance of T6 temper because RRA temper could produce larger sizes of both the matrix precipitates and GBPs than could T6 tempered condition.

• Sponsoring Organization: USDOE
• OSTI ID: 382513
• Journal Information: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, Journal Name: Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science Journal Issue: 9 Vol. 27; ISSN MMTAEB; ISSN 1073-5623
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
AIRCRAFT
ALUMINIUM BASE ALLOYS
ELECTRIC CONDUCTIVITY
FRACTURE PROPERTIES
GRAIN BOUNDARIES
GRAIN REFINEMENT
GRAIN SIZE
HEAT TREATMENTS
HYDROGEN EMBRITTLEMENT
MAGNESIUM ALLOYS
MATERIALS
PRECIPITATION
SLIP
STRESS CORROSION
ZINC ALLOYS