Optimizing surface quality of stainless alloys and using a modified ASTM G48B procedure for acceptance testing

The formation of high-temperature oxide scales and Cr-depleted zones on sta inless alloys, such as 6% Mo superaustenitic steels, can significantly redu ce their corrosion resistance. Effective methods to remove these layers and restore the surface to an "optimized" condition are detailed. Also, an acc eptance test using a modified ASTM G 48B method at 35 degrees C (95 degrees F) for 72 h with a specimen having a crevice, and special corrosion criter ia for failure, are described. Comparison of this test method with one usin g an uncreviced specimen at lower temperatures and for less time is discuss ed.