The use of steel 12X13
Stainless steel grade 12X13 is used as a corrosion-resistant structural material, including, welded parts and products with increased strength requirements, plasticity and impact strength, also resistance to mildly aggressive environments. Besides, steel grade 12X13 is used as a heat-resistant material at temperatures up to 400-450 °C and as heat-resistant - up to 700 ºS.
Chemical composition of steel 12X13
The chemical composition of steel 12X13 differs from the chemical composition of steel 08X13 only in the carbon content: 0,09-0,15 %, instead 0,00-0,08 %.
Steel class 12X13 according to GOST 5632-72
Transformations and microstructure of steel 12X13
- When heated annealed steel 12X13 polymorphic alpha-gamma transformation occurs in the interval between the lower and upper critical points: from 730 to 850 °FROM. The reverse transformation on cooling occurs in the Ar1-Ar3 range: from 820 to 700 °FROM.
- Isothermal holding at 800-550 °C leads to the decomposition of austenite into a ferrite-carbide mixture.
- The range of martensitic transformation of steel 12X13 is from 335 (Mn) to 245 °FROM (Mk), moreover, all austenite undergoes martensitic transformation.
- When tempering hardened steel 12X13, martensite decomposes into a ferrite-carbide mixture. Carbide formation starts at temperature 350-400 °FROM, and at lower temperatures only the removal of internal stresses occurs.
- An increase in the tempering temperature of the martensitic structure of steel 12Kh13 leads to a decrease in strength and an increase in plasticity and impact toughness with a slight decrease in corrosion resistance.
Steel assortment 12X13
The following products are made from 12X13 steel:
- thick sheet according to GOST 7350-77;
- thin sheet according to GOST 5582-75;
- tape according to GOST 4986-78;
- long products according to GOST 5949-75;
- hot-deformed pipes according to GOST 9940-81;
- cold-deformed and heat-deformed pipes in accordance with GOST 9941-81.
Mechanical properties of steel 12X13
Corrosion resistance of steel 12X13
Steel 12X13, like steel 08X13, has the first (higher) toughness score:
- in nitric acid with concentration 10-20 % at 40 °FROM;
- in nitric acid with concentration 30 % at 20 °FROM;
- in aqueous solutions of ammonia of all concentrations at a temperature 20-100 °FROM;
- in ethyl alcohol at room temperature;
- in sulfuric acid with concentration 90-100 % at room temperature.
Heat-resistant and heat-resistant properties of steel 12X13
As a heat-resistant material, steel 12X13 is used for the manufacture of turbine blades, fittings for cracking units, fasteners, bandages, details, boilers and other products for work with 450-550 °FROM.
As a heat-resistant material, steel 12X13 is used in ovens in pallets, screens, burners and other parts of furnaces at temperatures to 700 °FROM (table 4).
When steel 12X13 operates in a hydrogen atmosphere, its maximum permissible parameters are 600 °With and 80 MPa.
Physical properties of steel 12X13
Density of steel 12X13 – 7,75 g / cm3
Thermal conductivity of steel 12X13 – 28 W /(m ·°FROM)
Welding of steel 12X13
Steel 12X13 is satisfactorily welded by electric arc and argon-arc automatic and manual welding.
When welding rigid joints, as well as when welding products thicker than 10-12 mm welded joints or products are recommended to be heated to 250-400 °FROM. This is to prevent cold cracking..
After welding, welded joints or welded products must be tempered at 700-750 °C to relieve residual stresses and increase the strength of the weld.
Technological parameters of steel 12X13
- Steel 12X13 is plastically deformed in hot and cold states. The temperature range of hot plastic deformation is from 1200 to 850 °FROM.
- Ingots from steel 12X13 under hot deformation are heated with a landing in the furnace not higher than 800 °FROM.
- For steel 12X13, two heat treatment modes are usually used, providing an optimal combination of corrosion resistance with different levels of strength:
and) Quenching with 980-1020 °C in oil or air and leave at 250-400 °FROM, air cooling;
b) Quenching with 920-950 °C in oil or air and leave at 540-700 °FROM, air cooling.
- To provide steel 12X13 with maximum heat-resistant properties, quenching is used 1000-1050 °With air, in oil or water and leave at 650-750 °C and then air cooling, in oil or water.
- To relieve internal stresses and work hardening, use:
– vacation at 730-780 °With air-cooled or
– annealing at 850-900 °FROM, oven cooling.
Ulyanin EA. Corrosive steels and alloys, 1991.
Gulyaev A.P.. Metallurgy, 1986.