The stainless steel sulfuric acid test method is mainly used to distinguish 302, 304, 316 and 317 stainless steels. The samples to be identified are firstly ground, and then cleaned and passivated in nitric acid with a temperature of 60-66°C and a volume concentration of 20-30% for half an hour (specific gravity should be 1.42).
When the volume concentration of sulfuric acid solution is 10% and heated to 71°C, when 304 and 302 are immersed in it, they will be corroded rapidly and produce a lot of bubbles, and the sample will turn black in a few minutes; when 316 and 317 are immersed in it Basically not corroded, will not change color in a short time. The identification of stainless steel is meaningful both for the scrap recycling company and for the seller itself.
