DETECTION OF CHROMIUM SHORTAGE LAYER IN STAINLESS STEEL

PURPOSE:To obtain a method of detecting a chromium shortage layer existed in a high chromium stainless steel raw material and product in high accuracy and simply by utilizing a color developing reaction of Cu obtained from painting a stainless steel surface with an aqueous solution containing a prescribed concn. of Cu and Cl and of pH value controlled to a prescribed range as a detection liquid. CONSTITUTION:Cu concn. in the aqueous solution is in the range of 0.08-0.4 mol/l, and the color developing reaction of Cu is insufficient in 0.4mol/l concn. The Cl concn. in the aqueous solution is in the range of 0.2-0.7mol/l, the detecting sensibility is not raised in 0.7mol/l. The pH value of aqueous solution is in 0.3-3.5 range. Also the normal part is color developed in 3.5pH. The detecting liquid prepared thereby is coated on the stainless steel surface and the existence of Cu color developing (red color) is examined. Thereby, the chromium lack layer existed in the stainless steel can be detected highly precisely.