2018 Volume 67 Issue 4 Pages 168-171
C-ring stress corrosion tests under three conditions were carried out to investigate the effect of humidity and oxygen concentration on stress corrosion cracking of phosphorous deoxidized copper tubes. Three conditions were high humidity, low humidity and low oxygen conditions. The relative humidity and oxygen concentration were 100％ and about 20％ respectively in the high humidity condition. The air in the container with desiccant agent stored at a relative humidity of 90 to 95％ in the low humidity condition. In the low oxygen condition, the air in the container was replaced by the nitrogen gas and kept the concentration of oxygen less than 5％ during the exposure test. Although stress corrosion cracks occurred in the specimens exposed under both high humidity and low oxygen conditions, the time to occurrence of SCC under the low oxygen condition was longer than that under the high humidity condition. No SCC and intergranular corrosion developed in the specimen exposed under the low humidity condition for one week. It was found that lowering the humidity has an inhibitive effect on the SCC of the phosphorous deoxidized copper tube.
