Steel 12X13 - chrome stainless

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 %.

Table 1 – Chemical composition of steel 12X13 in accordance with GOST 5632-72stal-12x13-ximicheskiy-sostav

Steel class 12X13 according to GOST 5632-72

Martensite-ferritic.

Transformations and microstructure of steel 12X13

  1. 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.
  2. Isothermal holding at 800-550 °C leads to the decomposition of austenite into a ferrite-carbide mixture.
  3. The range of martensitic transformation of steel 12X13 is from 335 (Mn) to 245 °FROM (Mk), moreover, all austenite undergoes martensitic transformation.
  4. 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.
  5. 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

Table 2 - Mechanical properties of steel 12X13 at 20 °FROMstal-12x13-mexanicheskie-svojstva

Table 3 - Mechanical properties of steel 12X13
at high temperaturesstal-12x13-mexanicheskie-svojstva-temperatura

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.

Table 4 - Mechanical properties of steel 12X13
at elevated temperatures 12x13-mexsvojstva-vysokaja-temperatura

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.

Sources:
Ulyanin EA. Corrosive steels and alloys, 1991.
Gulyaev A.P.. Metallurgy, 1986.