Difference between 316 head and 304 head

Can the appearance of 316 head and 304 head be seen? 316 stainless steel head and 304 stainless steel head can not be distinguished by the naked eye. I look at it closely and I can't tell the difference.

Can the appearance of 316 head and 304 head be seen? 316 stainless steel head and 304 stainless steel head can not be distinguished by the naked eye. I look at it closely and I can't tell the difference.

Stainless steel refers to alloy steel with Cr content greater than or equal to 13% and stainless steel in the atmosphere. Various heads, oval stainless steel heads, spherical seals and other common materials are 304 and 316. Stainless steel, ordinary people understand, stainless steel is not rust steel. But in fact, there is no stainless steel material is super corrosion resistant, in popular terms, stainless steel is not easy to rust steel. In the end, stainless steel is a piece of steel with more impurities, but these impurities are more corrosion resistant than steel. 304 stainless steel --18/8 stainless steel. The GB brand is 0Cr18Ni9. The standard ingredient is 18% chromium and 8% nickel. Stainless steel that is non-magnetic and cannot change its metallographic structure by heat treatment. However, some magnetism is produced in the head products of the cold drawing process. The main difference between 316 and 304 in chemical composition is that 316 contains Mo. After 304, stainless steel model 316 is the second most widely used steel class.

All metals react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the iron oxide formed on ordinary carbon steel continues to oxidize, allowing the rust to expand and eventually form holes. The surface of carbon steel can be secured by electroplating with paint or oxidation-resistant metals such as zinc, but, as is known, this protection is only a thin film. If the protective layer is broken, the steel underneath will begin to rust. The corrosion resistance of stainless steel depends on chromium, but because chromium is one of the components of steel, the protection method is not the same. When the amount of chromium added reaches 10.5%, the atmospheric corrosion resistance of the steel is significantly increased, but when the chromium content is higher, although the corrosion resistance can still be improved, it is not obvious. Because when chromium is alloyed on steel, the type of surface oxide is changed to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface from further oxidation. This oxide layer is extremely thin, through which you can see the natural luster of the steel surface, giving stainless steel a unique surface. Moreover, if the surface layer is damaged, the exposed steel surface will react with the atmosphere to repair itself, re-forming this oxide "passivation film", which continues to play a protective role.

Compared with 304 stainless steel heads, 316 stainless steel heads have better corrosion resistance and are more resistant to corrosion at high temperatures than 304 heads. In concentrated sulfuric acid environment, do not use 316 at high temperature. 304 stainless steel head is widely used in food production equipment, drinking water equipment, general chemical equipment, nuclear energy and other equipment. Stainless steel 316 head is generally used in chemical industry equipment, pharmaceutical equipment, and Marine environment equipment, equipment with high corrosion resistance requirements.