Stainless steel grades and properties commonly used in instruments

1. 304 stainless steel. It is one of the most widely used austenitic stainless steels. It is suitable for the manufacture of deep-drawn parts and acid pipelines, containers, structural parts, and various instrument bodies. It can also be used to manufacture non-magnetic, low-temperature equipment and part.


2. 304L stainless steel. In order to solve the serious intergranular corrosion tendency of 304 stainless steel under some conditions due to the precipitation of Cr23C6, the ultra-low carbon austenitic stainless steel is developed, and its resistance to intergranular corrosion in the sensitized state is significantly better than that of 304 stainless steel. Except for slightly lower strength, other properties are the same as 321 stainless steel. It is mainly used for corrosion-resistant equipment and parts that cannot be solid solution treated after welding. It can be used to manufacture various instrument bodies, etc.


3. 304H stainless steel. The internal branch of 304 stainless steel has a carbon mass fraction of 0.04%-0.10%, and its high temperature performance is better than that of 304 stainless steel.


4. 316 stainless steel. Adding molybdenum on the basis of 10Cr18Ni12 steel makes the steel have good resistance to reducing medium and pitting corrosion resistance. In seawater and various other media, the corrosion resistance is better than 304 stainless steel, and it is mainly used for pitting corrosion resistant materials.


5. 316L stainless steel. Ultra-low carbon steel, with good resistance to sensitized intergranular corrosion, is suitable for the manufacture of welded parts and equipment with thick cross-sectional dimensions, such as corrosion-resistant materials in petrochemical equipment.


6. 316H stainless steel. The internal branch of 316 stainless steel has a carbon mass fraction of 0.04%-0.10%, and its high temperature performance is better than that of 316 stainless steel.


7. 317 stainless steel. Pitting corrosion resistance and creep resistance are better than 316L stainless steel, used in the manufacture of petrochemical and organic acid corrosion resistant equipment.


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8. 321 stainless steel. Titanium-stabilized austenitic stainless steel, adding titanium to improve intergranular corrosion resistance, and has good high-temperature mechanical properties, can be replaced by ultra-low carbon austenitic stainless steel. Except for special occasions such as high temperature or hydrogen corrosion resistance, it is not recommended for general use.


9. 347 stainless steel. Niobium-stabilized austenitic stainless steel, adding niobium to improve intergranular corrosion resistance, corrosion resistance in acid, alkali, salt and other corrosive media is the same as 321 stainless steel, good welding performance, can be used as corrosion-resistant materials and Hot steel is mainly used in thermal power and petrochemical fields, such as making containers, pipes, heat exchangers, shafts, furnace tubes in industrial furnaces, and furnace tube thermometers.


10. 904L stainless steel. Super complete austenitic stainless steel is a super austenitic stainless steel invented by Outokumpu Company of Finland. Its nickel mass fraction is 24%-26%, carbon mass fraction is less than 0.02%, and has excellent corrosion resistance. , has good corrosion resistance in non-oxidizing acids such as sulfuric acid, acetic acid, formic acid, phosphoric acid, and has good crevice corrosion resistance and stress corrosion resistance. It is suitable for sulfuric acid of various concentrations below 70°C, and has good corrosion resistance in acetic acid of any concentration and temperature under normal pressure and the mixed acid of formic acid and acetic acid. The original standard ASMESB-625 classified it as a nickel-based alloy, and the new standard classified it as a stainless steel. China only has a similar grade of 015Cr19Ni26Mo5Cu2 steel, and a few European instrument manufacturers use 904L stainless steel as the key material. For example, the measuring tube of the mass flow meter of E+H is made of 904L stainless steel, and the case of Rolex watches is also made of 904L stainless steel.


11. 440C stainless steel. Martensitic stainless steel has the highest hardness among hardenable stainless steel and stainless steel, with a hardness of HRC57. It is mainly used to make nozzles, bearings, valve cores, valve seats, sleeves, valve stems, etc.


12. 17-4PH stainless steel. Martensitic precipitation hardening stainless steel, with a hardness of HRC44, has high strength, hardness and corrosion resistance, and cannot be used at temperatures higher than 300°C. It has good corrosion resistance to the atmosphere and diluted acid or salt. Its corrosion resistance is the same as that of 304 stainless steel and 430 stainless steel. It is used to manufacture offshore platforms, turbine blades, valve cores, valve seats, sleeves, and valve stems. wait.