DECISION ON AGING IN CHROME-MOLYBDENUM STEEL

摘要

PURPOSE:To decide on aging in Cr.Mo steel non-destructively and at a high accuracy, by employing an aqueous solution with a specified composition of picric acid, dodecyl sodium benzenesulfonate of dimethyl sodium benzenesulfonate as an electrolytic liquid. CONSTITUTION:An aqueous solution containing 0.15-0.16wt.% of picric acid and 0.07-0.3wt.% of dodecyl sodium benzenesulfonate or demithul sodium benzenesulfonate or dimethyl sodium benzenesulfonate is used as electrolytic liquid for decision on aging caused by the high temperature use of Cr.Mo steel. After immersed into the electrolytic liquid for about five minute, a sample electrode of Cr.Mo steel to be measured is swept in the reverse direction from the natural potential A and after held for two minute at the passivity potential C, it is swept reversely at the same speed again to measure the maximum D of current density in a polarization curve. The maximum D is called as minimum current density D. The value D in creases with aging and has a high correlation with Charpy fracture transition temperature. This enables non- destructive measurement of aging non-destructively in a short time at a high density and at a high accuracy.