Stainless steel refers to steel that is resistant to weak corrosive media such as air, steam, water, and chemically etched media such as acids, alkalis, and salts. It is made of iron-chromium alloy and other trace elements. Due to its good metal properties and corrosion resistance compared to other metals, the finished vessel is aesthetically pleasing and durable.

1. Does stainless steel really rust?

Real stainless steel products should last for hundreds of years without rusting. But the stainless steel we see on the market can still be rusted and corroded, but in general, the rate of corrosion is very slow. I have done this test: two pieces of stainless steel and ordinary carbon steel with a weight of 20 grams were put together in dilute nitric acid for a day and night. As a result, ordinary steel was strongly corroded, leaving only 13.6 grams, while stainless steel weighed 19.8. Gram. Because stainless steel is not easy to rust, many corrosion-resistant equipment in chemical plants is made of stainless steel.

Whether stainless steel is prone to rust, the content of chromium is the key. In China, the minimum chromium content in stainless steel is not less than 12%. Due to the high proportion of chromium in the stainless steel composition, the surface is always in a passivated state under normal conditions (neutral and alkaline), that is to say, it has a tight protective film to protect it from rust. If the chromium content is low, that is, inferior stainless steel, the surface cannot produce a sufficiently tight passivation film, which cannot protect it. The stainless steel still needs to rust. In another case, the stainless steel encounters a very active substance (such as salt in life) and contains high chlorine or fluoride ions. Even the high-quality stainless steel with high chromium content will destroy the passivation film on the surface. In order to make the surface of the stainless steel active, stainless steel will not only rust, but also dissolve heavy metal ions harmful to the body.

2. How to choose qualified stainless steel products?

Household stainless steel cutlery can be divided into three levels of 430, 18-8, and 18-10. 430 stainless steel, which is composed of iron +12% or more, can prevent oxidation caused by natural factors. It is called stainless steel, but it will rust after prolonged use. 18-8, its composition is iron +18% chromium +8% nickel, 18-10 its composition is iron +18% chromium +10% nickel. Chromium is a material that does not rust the product, and nickel is a corrosion-resistant material. The higher the nickel content, the better the quality of the product and the more expensive it is. Strictly speaking, products containing only chromium and not containing nickel are stainless steel, and products containing both it is usually possible to try it with a magnet when it is purchased. Stainless steel products are attracted to the magnet and stainless steel products are not attracted to the magnet. There have been two types of stainless steel products marked "201" on the market, the composition of which does not meet the relevant standards of stainless steel, but the brand of stainless steel appears on the market. On the surface, this product is difficult to distinguish from ordinary stainless steel, and it is non-magnetic, which is very easy to cause confusion among consumers. It is the "Li Gui" in stainless steel. The simplest way to judge it is that it is cheap. Real high-quality stainless steel must be a price-for-money, expensive reason. Chemical method can be used to identify the authenticity of stainless steel. In 100mL distilled water, 8g of anhydrous copper sulfate is added, and then 3 drops of concentrated sulfuric acid are added. The solution is dropped on the surface of the stainless steel product for 6 minutes, and the surface of the real stainless steel product does not change. A layer of red material is produced on the surface of the unqualified product.

In addition to the purchase of stainless steel products should also pay attention to the following two aspects: a look at the color, the color is black and black, it is likely to be stainless iron; the color is dark and red, it is likely to replace nickel with manganese. 2 touched by hand, the edge can not have burrs, the surface is smooth, no scratches, no blisters.

3. How to maintain stainless steel kitchen utensils?

In the home, the kitchen utensils are the most frequently used and the most vulnerable. Kitchenware always has to deal with water and fire. If you don't take care of it, your life will be shortened. How should we maintain it so that it can be as new as ever?

before use:

(1) When the stainless steel cookware is used for the first time, it should be boiled with water for half an hour, then soaked for several hours, then replaced with new water and repeatedly boiled and soaked. Generally, repeated three times or more will reduce the heavy metal migration to a safe level.

(2) A thin layer of vegetable oil can be applied to the surface of the vessel and then dried on the fire. This is equivalent to wearing a yellowish oil film "clothing" on the surface of the vessel. In this way, it is easy to clean and extend the service life.

when using it:

(1) tableware should avoid collision with sharp objects, so as to avoid scratches and scars affecting the appearance and sealing performance.

(2) Due to the small thermal conductivity of stainless steel, the heat dissipation at the bottom is slow, and the temperature is easy to concentrate. Therefore, when using stainless steel cookware, the firepower should not be too large. The bottom heating surface should be as wide and uniform as possible so as to save fuel and avoid burning of food at the bottom of the pan. .

(3) It is not allowed to hold salt, soy sauce, vinegar, vegetable soup, etc. for a long time. Because these foods contain a lot of electrolytes, if they are kept for a long time, stainless steel will also react with these electrolytes like other metals. Toxic metal elements are dissolved.

(4) It is not possible to use traditional Chinese medicine in stainless steel pots, because Chinese medicine contains a variety of alkaloids, organic acids and other ingredients, especially under heating conditions, it is very likely that chemical reactions will occur, which may cause the drug to fail and even produce some more toxic. substance.

After use:

(1) Wash with warm water immediately after use to avoid the effects of oil stains, soy sauce, vinegar, tomato juice and other utensils on the surface of the tableware, resulting in dull color and even dents on the surface of the stainless steel. When washing, be careful not to scratch the surface, avoid using bleaching ingredients and abrasive-containing washing liquid, steel balls, grinding tools, etc., and wash them with soap and weak washing. If the bottom of the pot is cokeed with food, it can be softened with water and then scraped off with bamboo and wood chips. After the utensils are cleaned, the water traces on the outside should be dried. Remember to keep the appliance dry.

(2) After using the tableware for a period of time, the surface of the stainless steel will have a mist, which will make the surface of the tableware dark. At this time, you can use a soft cloth dampened with decontamination powder or detergent to restore the light. This method can also be used if the outer surface is blackened by smoke.

(3) If the stainless steel tableware has turned black, if you want to make it shine as before, you can use the commercially available “electroplating rust remover” for maintenance and rust removal. If there is rust, you can soak it in water for one night, then use a small piece of 1000 water sandpaper and use your fingers to carefully grind it in the blackened area.