Stainless steel kitchen utensils have a series of high-quality features such as high temperature resistance, non-rust, and acid resistance, which also makes stainless steel kitchenware more and more used in our daily life. So how to identify the quality of stainless steel kitchen utensils?
1. Identification of color
Pickled stainless steel kitchen utensils, the surface color of silver and white smooth: chromium nickel stainless steel kitchen utensils color is white jade; chrome stainless steel kitchen utensils white slightly gray glossy weak; chromium manganese nitrogen stainless steel kitchen utensils and chromium nickel stainless steel kitchen utensils is a bit pale. The surface color of the unpickled stainless steel cookware: Chrome-nickel steel is brownish white, chrome steel is brownish black, and chromium-manganese nitrogen is black (these three shades are heavily oxidized). Cold-rolled unannealed chromium-nickel stainless steel with silver-white surface.
2. Identification with copper sulfate
Can remove the oxide layer of the stainless steel kitchen utensils, put a drop of water, use copper sulfate to wipe, if you do not change color after rubbing, then generally stainless steel; if it becomes purple, non-magnetic high-manganese steel kitchenware, magnetic Generally ordinary steel or low alloy steel. For steels with special properties, we need to adopt the following three methods for identification.
3. Identification with magnets
Magnets can basically distinguish between two types of stainless steel. Because the chromium stainless steel kitchenware can be attracted by the magnet in any state; the chromium nickel stainless steel kitchenware is generally non-magnetic in the annealed state, and after the cold processing, some are magnetic. However, manganese-rich steels with higher manganese content are non-magnetic; chromium-nickel-nitrogen stainless steel kitchenwares are more complex in terms of magnetic properties: some are non-magnetic, some are magnetic, and some have a non-magnetic vertical surface and a magnetic surface. Therefore, although magnets can basically distinguish between chromium stainless steel kitchen utensils and chromium nickel stainless steel kitchen utensils, they cannot correctly distinguish some special-purpose steel grades, and they cannot distinguish specific steel grades. However, some stainless steel kitchenware manufacturers on the market use this point to manufacture stainless steel kitchen utensils that cannot be tested by magnets, so they need to be careful.
4. Annealing identification
Cold-worked chrome-nickel stainless steel cookware, if magnetic, may preferably be red-hot in fire to allow it to cool naturally or in water (annealing). In general, after annealing, the magnetic properties will be significantly reduced or completely disappear. However, some chromium nickel stainless steel kitchenware, such as Cr18Ni11Si4AlTi steel and Cr21Ni5Ti steel, because the steel contains more ferrite elements, a considerable part of its internal structure is ferrite. Therefore, it is magnetic even in the hot working state.
5 grinding flower identification
Grinding is to identify the stainless steel kitchen utensils on the grinder, watch its spark. Such as sparks are streamlined, and there are more dense section of the flower, that is, high manganese high manganese steel kitchen utensils or manganese nitrogen steel kitchen utensils; if no flowers are chromium steel kitchen utensils or chromium nickel stainless steel kitchen utensils.
6. Chemical qualitative identification
Chemical characterization is a method of identifying whether or not kitchenware in a magnetic stainless steel contains nickel. The method is to dissolve the small stainless steel in acid water, dilute the acid with clean water, add ammonia water, and then gently inject the nickel reagent. If there is a red fluffy substance floating on the liquid surface, it means that the stainless steel kitchenware contains nickel; if there is no red fluffy material, it proves that the stainless steel kitchenware is free of nickel (but because of the low nickel content in stainless steel, it is generally only a few percent. Nickel content is not easy to reveal or determine how much, in general, the standard sample must be used after many experiments.)
However, if 100% identification is required, an in-depth investigation and study is required, and the testing unit is required to make a test determination. This is the fundamental way to correctly distinguish stainless steel grades and quality, and it is also the most authoritative method to reduce your exposure to pits!