What kind of corrosion is stainless steel afraid of? Under what circumstances is ordinary stainless

Stainless steel is resistant to acids and high-temperature corrosion. Stainless steel is soaked in acids or burned at high temperatures to reduce its corrosion point, and the corrosion point of rusty steel occurs from individual points on the surface of stainless steel, and then expands to depth. Stainless steel if exposed to contain halogens.

The aqueous solution of ions, these active ions can destroy the passivation film on the surface of stainless steel, and this pitting corrosion will be caused in the weak part.

It is most afraid of acids and high-temperature corrosion. Stainless steel is resistant to air, steam, water and other weak corrosive media or stainless steel grades, the full name is stainless acid resistant steel, after acid soaking or high temperature burning will reduce the anti-corrosion point of stainless steel, so as to be corroded.

Different grades of stainless steel have different resistance to different corrosion.

Generally speaking, stainless steel without molybdenum is less resistant to chloride corrosion;

The resistance of most stainless steels to biological acids is not ideal;

Almost all stainless steels are not resistant to galvanic corrosion;

The corrosion resistance and non-corrosion resistance of stainless steel are usually relative. Industrial storage tanks, pipes that become thinner by one or two millimeters per year can be considered corrosion-resistant. And a small trachoma that has been corroded for a few years can be considered not corrosion-resistant.

My stainless steel planters all started to corrode and perforate at the surface of the soil, that is, at the interface between the soil and the air, so I think it was potential corrosion.

Ordinary stainless steel can be toxic in the following situations:

1. Long-term salt, light soy sauce, scalding water, etc., because this food contains a lot of electrolyte solution, such as long-term storage, stainless steel plate will be like other metal materials, and this electrolyte solution produces electrochemical corrosion, so that the harmful chemical elements are dissolved.

2. Clean stainless steel cookware with strong alkali or strong oxidizing organic chemicals, such as baking soda, bleach, calcium hydroxide, etc. Since this substance is an electrolyte solution, it will have chemical changes with stainless steel plates, and then cause substances that are harmful to the body.

3. Use stainless steel plate containers to boil Chinese herbal medicines. Because Chinese herbal medicines contain many flavonoids, citric acid and even ingredients, especially under the heating standard, it is difficult to prevent chemical changes with them, which makes the drug ineffective, and even converted into some more toxic compounds.

Common metal cutlery:

1. Copper tableware: copper is easy to produce patina (copper hydrogen dioxide dicooxide) in a humid environment, and it is easy to oxidize in the air to produce green powder (copper oxide). These substances are harmful to human health. As a result, copper cutlery has been gradually phased out.

2. Iron tableware: Iron tableware itself is non-toxic, but iron utensils are easy to rust, and after rusting, they exude a bloody smell, which will lead to nausea and poor appetite. Moreover, iron tableware is not suitable for holding cooking oil, oil and iron products are easy to oxidize and deteriorate together, and iron containers are not suitable for holding tea and coffee.

3. Stainless steel tableware: stainless steel metal has good performance, corrosion resistance than other metals, and the tableware made is beautiful and durable. Therefore, stainless steel is increasingly used to make tableware and gradually enter the majority of households.

4. Aluminum tableware: Aluminum tableware is non-toxic and lightweight, but long-term use will accelerate human aging and is not good for human memory. Therefore, it is best not to cook acidic and alkaline ingredients for aluminum tableware, and also avoid using it to store meals and salty dishes.

5. Titanium tableware: The unique titanium tableware has a warm luster, a delicate texture comparable to silver tableware, and the material is light in weight and has many excellent characteristics. Titanium tableware is stable in nature, high in aesthetics, and there are almost no contraindications in use, but ** is higher.

Ordinary stainless steel is not toxic. Stainless steel does contain chromium, and it is theoretically possible for chromium to migrate into water as well. However, there are national standards for stainless steel used in catering containers that specify the amount of migration under specific conditions.

The allowable amount of migration itself is much lower than the amount that can be harmful to health, and in reality, the food contained (such as tea) is far milder than the "specific conditions" of the national standard. In other words, in reality, even if there is a precipitation of chromium in normal food, it is far from a "harmful" amount.

Precautions for the use of stainless steel

For any stainless steel pot, do not wash the stainless steel pot with strong alkaline or oxidizing chemicals, such as soda, bleaching powder, sodium hypochlorite, etc., to avoid corrosion of the product. Do not use too much heat to heat (using high heat can easily cause discoloration of the product).

The stainless steel pot contains chromium and nickel, these two elements can withstand high temperatures below 400 without corrosion in a non-strong acid or non-strong alkali environment, but if you are in contact with acid and alkali foods for a long time, it will also cause chemical reactions, so it is not suitable to hold salt, soy sauce, vegetable soup for a long time, and you can not decoction.

The above content refers to Encyclopedia - Stainless Steel.

Stainless steel itself is non-toxic. If it is food-grade stainless steel, such as 304 stainless steel, the stainless steel used for catering containers meets national standards and is generally harmless to the body. Instead of food-grade stainless steel, it contains heavy metals, which are toxic and harmful to the body.

Do not store vinegar, salt, etc.: stainless steel tableware should not hold salt, soy sauce, vinegar, vegetable soup and other liquids for a long time, and should not hold acidic juices such as orange juice.

Do not clean with strong alkaline detergents: such as baking soda, bleaching powder, sodium hypochlorite, etc., these strong electrolytes can "electrochemically react" with metal elements and dissolve harmful elements.

Do not boil traditional Chinese medicine: Chinese medicine contains a variety of alkaloids, organic acids and other components, which may react chemically with the metal elements in the tableware when heated, making the drug ineffective and even generating toxic substances.