How to Identify stainless Steel Material Grades?
At present, on Chinese market of stainless steel materials, there are many suppliers passing fish eyes for pearls. So, it is necessary to check whether the flat sheets or plates are real stainless steel. But how to identify these stainless material grades? Below are several methods.
1. PMI machine test.This instrument is small and portable. It can be used to examine the category and elements of each grade of stainless steel.
2. Chemical Reagent: Drop a special reagent named nickel qualitative solution onto the surface of stainless steel, the surface will immediately be oxidized after electrification then
if the surface turns into pale white or light yellow color, it means this stainless steel sheet is nickel free;
if the surface becomes a pale rose red then immediately fades to a deep yellow color which means this stainless steel plate contains about 1%- 2% nickel;
if the rose red color does not fade which means the stainless steel sheet contains more than 4% nickel;
The more vivid rose red the higher nickel content.
Color for the surface of pickled stainless steel sheet
304 grade: silver white and jade
400 series: white and slightly grey with weak luster
200 series and 300 series: slightly lighter color
Color for the surface of non pickled stainless steel sheet
304 grade: brown and white
400 series: brown and black
200 series: black