What is the high temperature resistance limit of stainless steel 304?

The high temperature resistance limit of 304 stainless steel is 800 degrees.

Identification method of 304 stainless steel plate;

Stainless steel identification agent is used for identification.

(1) Stainless steel appraisers are used to detect the nickel content of steel to distinguish which series of stainless steel it is. Rapid detection of 200 series, 300 series, 400 series and other stainless steels has a variety of specifications. The use method of stainless steel appraiser is very simple, just drop it directly on the stainless steel plate. General stainless steel appraisers can take effect in about 2-3 minutes, and different colors correspond to different types of stainless steel materials.

(2) Ordinary 20 1 stainless steel 10 seconds turns red (manganese exceeds the standard); Authentic 20 1 stainless steel turns red in about 50 seconds (manganese exceeds the standard); 202 stainless steel turns red about 1 min (manganese exceeds the standard); 30 1 stainless steel will turn red in 2-3 minutes, but the color is very light, so you need to look carefully. If the color doesn't change within 3 minutes, and the color at the bottom is slightly darker, this is authentic SUS304 stainless steel.

(3) Generally, stainless steel appraisers are equipped with contrast color cards. It is very convenient to know the model of stainless steel plate by directly comparing the appraisal results.

Identification of 304 stainless steel by magnetism.

(1) First of all, we know that 304 stainless steel belongs to the austenitic type, but the austenitic type is nonmagnetic or weakly magnetic, so people will think that a good stainless steel is nonmagnetic. However, it is neglected that 304 stainless steel may appear magnetic when its chemical composition fluctuates or its processing state is different due to the smelting process, but it cannot be considered as a counterfeit or unqualified product. In addition, the microstructure of 304 stainless steel will also transform into martensite after cold working. The greater the cold deformation, the more martensite transformation and the stronger the magnetic properties of steel.

(2) On the contrary, the inferior quality 200 series stainless steel is likely to be nonmagnetic, so it is a big mistake to judge that it is genuine stainless steel. In particular, the magnetism of 304 stainless steel caused by the above reasons is not at the same level as that of other stainless steels, that is to say, the magnetism of 304 steel is always weak. This tells us that if stainless steel has weak magnetism or no magnetism at all, it should be judged as 304 or 3 16 material; If it is the same as carbon steel, it shows strong magnetism, because it is judged that it is not made of 304 material.

Identified with copper sulfate. Remove the oxide layer from the steel, drop a drop of water on it and wipe it with copper sulfate. If it does not change color after wiping, it is generally stainless steel; If it turns purple, high manganese steel is nonmagnetic, while ordinary steel or low alloy steel is magnetic.

, grinding identification. Grinding identification is to grind stainless steel on a grinding machine and observe its sparks. If the spark is streamlined and has many dense knots, it is high manganese steel or manganese-nitrogen steel with high manganese content; If there is no knot, it is chrome steel or chrome-nickel stainless steel.

Chemical qualitative identification method.

(1) chemical qualitative method is a method to identify whether magnetic stainless steel contains nickel. The method is to dissolve a small piece of stainless steel in aqua regia, dilute the acid solution with clear water, add ammonia water for neutralization, and then gently inject nickel reagent.

(2) If there is red fluff floating on the liquid surface, it means that the stainless steel contains nickel; If there is no red velvet substance, it is proved that stainless steel does not contain nickel (however, due to the low nickel content in stainless steel, which is generally only a few percent, it is difficult to reveal or determine how much nickel is contained, and it is generally necessary to conduct many experiments with standard samples to master it).