When purchasing stainless steel pipe fittings, facing various brands, manufacturers and models, everyone does not know how to choose qualified products. Therefore, everyone must master the correct identification method. Today, I will introduce to you how to identify the authenticity, hoping to help you choose the products you are satisfied with.
1. Identification of color
The surface color of stainless steel pipe fittings after pickling is silvery white and smooth: chromium-nickel stainless steel is silvery white and jade-colored; chromium stainless steel is white and slightly gray and has a weak luster; the color of chromium-manganese-nitrogen stainless steel is similar to chromium-nickel stainless steel and slightly lighter. The surface color of stainless steel that has not been pickled: chromium-nickel steel is brown-white, chromium steel is brown-black, and chromium-manganese-nitrogen is black (these three colors refer to the colors of heavier oxidation). Cold-rolled chromium-nickel stainless steel that has not been annealed has a silvery white and reflective surface.
2. Identification with a magnet
Magnets can basically distinguish between two types of stainless steel. Because chromium stainless steel can be attracted by magnets in any state; chromium-nickel stainless steel is generally non-magnetic in the annealed state, and some will be magnetic after cold processing. However, high manganese steel with a high manganese content is non-magnetic; the magnetic situation of chromium-nickel-nitrogen stainless steel is more complicated: some are non-magnetic, some are magnetic, and some are non-magnetic in the longitudinal direction but magnetic in the transverse direction. Therefore, although magnets can basically distinguish chromium stainless steel and chromium-nickel stainless steel, they cannot correctly distinguish some special types of steel, let alone specific steel grades.
3. Identification with copper sulfate
Remove the oxide layer on the steel, put a drop of water on it, and rub it with copper sulfate. If it does not change color after rubbing, it is generally stainless steel; if it turns purple-red, it is high manganese steel that is non-magnetic, and magnetic steel is generally ordinary steel or low alloy steel.
