SEDL / STP / STP610-EB / STP28675S

Stress-Corrosion Crack Growth in Surface-Cracked Panels of High-Strength Steels

Shahinian, P
Consultant and head, Naval Research Laboratory, Washington, D. C.

Judy, RW
Consultant and head, Naval Research Laboratory, Washington, D. C.

Pages: 15    Published: Jan 1976

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Abstract

Stress-corrosion crack growth in 17-4PH and 4340 steels in 3.5 percent sodium chloride solution was examined over a wide range of K^Iscc/σ^ys values by electrochemically coupling the 17-4PH steel to aluminum, zinc, magnesium, and open circuit and by testing the 4340 steel at three strength levels in open circuit.

It was demonstrated that the parameter, K^Iscc, determined from small cantilever bend specimens can be used to predict the flaw size/stress level combinations required for the onset of crack growth in large surface-cracked tensile panels. For this purpose the stress-intensity values for the surface-cracked panels were calculated from the basic surface-flaw equation.

The microfracture processes in the stress-corrosion cracking included intergranular, cleavage, and microvoid coalescence, the proportion of intergranular became greater with increase in negative electrochemical potential.