THE EFFECTS OF THREE AQUEOUS ENVIRONMENTS ON HIGH STRESS LOW-CYCLE FATIGUE OF 18% NICKEL MARAGING STEELS.

Base plate and weld specimens of 200 ksi and 250 ksi nominal yield grades of 18 Ni maraging steels were tested as side-grooved plane-strain cantilever beam specimens in distilled water, water inhibited with NaCrO4, and 3-12 NaCl solution, to determine the susceptibilities of these steels to both corrosion fatigue and sustained load crack growth. Stress intensities below which negligible crack growth occurred during twenty cycles were found to be about 95 of K sub Ic for 250 grade base plate in distilled water, 73 of K sub Ic for 250 grade tested in either the salt water or the sodium chromate solution, 88 of K sub Ic for the 200 ksi grade base plate in all three environments, and essentially 100 of K sub Ic for the 200 ksi weld metal in all three environments. Crack extension was found to be negligible in twenty cycles at a K sub I of 65 ksi square root inches in the 250 ksi grade welds in all environments. Author