Validity of a new fracture mechanics technique for the determination of the threshold stress intensity factor for stress corrosion cracking (KIscc) and crack growth rate of engineering materials

A novel fracture mechanics technique has been employed for the determination of crack growth rate and threshold stress intensity factor for stress corrosion cracking (KIscc) using small circumferential notch tensile (CNT) specimens. The technique was applied successfully for testing SCC susceptibility of heat treated 4340 steel in sodium chloride (NaCl) solutions at room temperature. Crack growth rates have been determined at different stress intensity factors (KI), and the KIscc has been determined to be 15 MPa m1/2. The obtained KIscc value using CNT specimen was found to be very close to KIscc values obtained by others using standard specimens.