A significant part of technological processes in various fields of industry does not allow the use of ordinary steel grades due to their low resistance to corrosion or the effects of aggressive media. In these situations, the best option is to use stainless steels, among which the most common is the AISI 321 /SS 321 brand, or its Russian counterpart 08X18H10T .
Main characteristics of the AISI 321 brand
Stainless steel AISI 321 according to the site https ://emk24.ru/wiki/astm_steels/stal_aisi_321_4370927/, belongs to the austenitic group and has a high content of chromium (17-19%) and nickel ( 9-12%). As related alloying additives used:
- titanium (up to 0.5%);
- silicon (up to 1%);
- phosphorus (no more than 0.045%);
- manganese (up to 2%).
The presence of titanium in the alloy provides resistance to intercrystalline corrosion. The balanced chemical composition of AISI 321 steel allows it to be used at high temperatures without losing its unique properties. The recommended range is 600-800 gr. Celsius. In this case, the ultimate strength is from 390 to 180 MPa.
AISI 321 steel structures are welded with 347 series Nb-stabilized electrodes. Moreover, the junction of the parts does not require subsequent heat treatment.
If annealing is required, there is no need to use additional ingredients. This operation is carried out at a temperature of 1050-1150 ° C, followed by cooling in the open air.
To reduce gas corrosion, the surface of AISI 321 /SS 321 steel products must be passivated with 20-25% nitric acid solution at a temperature not exceeding 20 ° C. Preliminary cleaning is carried out with a mixture of nitric and hydrofluoric (hydrofluoric) acids. It is possible to use a sulfur-nitrogen solution in the proportion - 10% H2SO4 + 0.5% HNO3. The temperature should not exceed 60 ° C.
Main Applications of AISI 321 /SS 321 Stainless Steel
This grade of steel is in demand in the chemical, petrochemical industry in the manufacture of equipment, parts of which come into contact with aggressive media, are exposed to high temperatures or experience shock effects of various alternating nature.
