Accession Number:

AD0725166

Title:

The Role of Passive Film Growth Kinetics and Properties in Stress Corrosion Susceptibility

Descriptive Note:

Technical summary rept. no. 2, 1 Mar 1970-28 Feb 1971

Corporate Author:

NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD

Report Date:

1971-05-13

Pagination or Media Count:

67.0

Abstract:

A new technique has been developed for studying the rate of repassivation of a stressed metal surface exposed by film rupture. This technique, which removes the film on a metal by abrasion and then follows film regrowth and metal dissolution by transient ellipsometry and current transients, was applied to low carbon steel in a nitrate solution where it stress cracks and a nitrite where it does not. The rate of repassivation was greater in the non- susceptible solution while the ratio of current going into film formation to that producing metal dissolution was less. Another new technique was developed which measures the ductility of films on metal surfaces by determining by ellipsometry the amount of thinning the film undergoes upon straining the metal. The technique gives values for maximum ductility of the film rather than the fracture strain that other techniques give. Measurements were made on anodic films on Ta, Al and Al-4 Cu.

Subject Categories:

  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE