Results of corrosion fatigue tests of a plain carbon steel in brines containing oxygen, carbon dioxide, hydrogen sulfide and combination of these gases are presented.
Apparatus was designed to fatigue test sheet specimens in any environment in the absence of air. The arrangement provided for complete immersion of four samples while applying cyclical bending stresses.
AISI 1035 steel sheets with a 29,000 psi air endurance limit at a cycling frequency of 600 cycles per minute were tested. Aeration of the brine reduced this endurance limit by 65 percent to a value of 10,000 psi. Removal of oxygen from brine increased the endurance limit to 30,000 psi.
The endurance limit in brine saturated with CO2 gas was 17,000 psi. Oxygen introduced into this system did not have a pronounced effect on corrosion fatigue performance. H2S-saturated brine had the least damaging effect of all environments. Endurance limit of the steel in H2S-saturated brine was 23,000 psi. When air or CO2 was introduced into this system endurance limits were reduced by 52 percent and 62 percent, respectively.
Test results are discussed in the light of information on corrosion reactions in these environments.
