Effect of Salt Water Temperature on the Crack Growth Characteristics of 12 Chrome Steel

Abstract

The corrosion fatigue crack growth rates on 12 chrome steels of typical composition, 12Cr, 0.2C, 1Mo, 1W, of 150,000-ksi yield is relatively unaffected by 4.5 percent NaCl salt water solution at room temperature. There is a significant rise in the crack growth rates of 12 chrome steels with increasing temperature for salt water corrosion fatigue of about 4 to 1 for 160 deg F—4.5 percent solution. In correlating rotating beam understressing data on average crack growth rate versus stress intensity factor with 0-maximum data generated by other techniques, the value 1 − R Kmax equivalent to n = 0.5 in the expression Keff = Kmax (1 − R)n correlates the rotating beam data adequately with the 0-Max data for other techniques. A correction factor for eccentric crack fronts on solid round specimens for rotating beam crack growth data to calculate stress intensity factors for solid notched round bars has been developed. The correction term is 4rd2 for the following stress intensity expression. K1=2.257Mr3+4rd20.80t+7.12r−1/2