Critical Contents of Nickel and Chromium Required for SCC Resistance of High Alloy Oil Country Tubular Goods

Based on the laboratory SCC test results of 10 to 37% Cr, 25 to 45% Ni, 3% Mo, bal. Fe alloys, it is shown that the beneficial effect of increased Ni content on SCC resistance is retained only when the Cr content is appropriate. Good SCC resistance is obtained when the stability of austenite is above a critical value; therefore, the content of ferrite formers, e.g., Cr and Mo, should not exceed a certain limit determined by the content of austenite formers, e.g., Ni. The critical stability of austenite depends on the annealing temperature, a higher temperature requiring a higher stability of austenite.