Modification of ASTM Standard B117 Salt Spray Corrosion Test for Improved Correlation to Field Measurements

Modification of ASTM Standard B117 Salt Spray Corrosion Test for Improved Correlation to Field Measurements

Ye Wan, Robert G. Kelly

Dept. of Materials Sci. & Eng., Univ. of Virginia

Charlottesville, VA, USA 22904

yw8h@virginia.edu

This work is concerned with the modification of the conventional salt spray corrosion test (e.g., ASTM Standard B117) that is often used to accelerate the natural marine atmospheric corrosion of materials. The conventional B117 test creates and maintains a controlled salt spray environment to which materials of interest are exposed. However, the results from the B117 test are seldom correlated with the corrosion behavior and performance observed in actual exposures.  For example, silver, when exposed to actual atmospheric environments forms an AgCl film the thickness of which depends on the corrosivity of the exposure site.  When exposed to the B117 environment, silver forms no AgCl even after four months of testing.  Recent work has shown that the more oxidizing character of natural environments relative to B117 can be reproduced in the laboratory testing via the introduction of UV light and ozone to the test environment.   Two subsystems were designed and constructed to modify the commercial chamber.  A UV light resource rack consists of UV lamps mounted on a removable rack, which allows them to be positioned to achieve the desired UV light intensity.  An ozone system consisted of a commercial ozone generator and a distribution system that allowed a uniform concentration of ozone throughout the chamber up to 20ppm.  Details of the modifications as well as results for silver and steel will be presented.