Circumferential Notched Tensile Testing for Correlation of the Stress Intensity Factor (K _I ) and Stress Corrosion Crack Growth Rate

A novel fracture mechanics technique has been employed for the determination of crack growth rate and threshold stress intensity factor (K _ISCC) for stress corrosion cracking (SCC) using small circumferential notch tensile (CNT) specimens. The technique was applied successfully for testing SCC susceptibility of AISI 1020 mild steel in 12.5 M NaOH at 150 °C. The crack growth rate of mild steel in 12.5 M NaOH solution at 150 °C has been determined at different stress intensity factors (K _I ), and the K _ISCC has been determined to be 29 MPa·m^1/2. The surfaces of fractured specimens have been examined by scanning electron microscopy (SEM) in order to establish intergranular propagation of stress corrosion cracks. The CNT testing is a simple, relatively fast, and cost-advantageous approach for generating crack growth rate and K _ISCC data.