Classification of chromium stainless steels
Steel 30Х13. According to its properties and application, steel 30X13 is similar to steel 40X13. Corrosion resistance of steel 30X13 is slightly higher, than steel 40X13, and the strength characteristics – somewhat lower.
Application of steel 40X13
Steel 40X13 is used:
- as a corrosion-resistant material with high hardness for:
– cutting, measuring and surgical instruments;
– springs, bearings and other products, working for wear in mildly aggressive environments;
– household appliances and household items.;
- as a heat-resistant and heat-resistant material when working up to 400-450 °C for fasteners, shafts, elastic elements, exposed to mildly aggressive environments, eg, in oil refining.
Steel 40X13 is not welded.
Chemical composition of steel 40X13
Steel 40X13 is included in the group of steels of type X13 together with steels 08X13, 12Х13, 20X13 and 30X13. It occupies its own range in terms of carbon content - from 0,36 to 0,45 %, the amounts of other alloying elements and impurities are the same, like other steels of type X13 (table 1).
Transformations and microstructure of steel 40X13
- When heated, 40X13 steel has a polymorphic alpha-gamma transformation in the temperature range from 820 °FROM (As1) to 880 (As3).
- When heated slightly above the temperature of the Ac point3 the steel structure consists of austenite and chromium carbides of the Cr type23C6. Complete dissolution of carbides occurs when 950-1000 °FROM.
- Steel 40X13 has the best corrosion resistance after quenching from temperature, which ensures complete dissolution of carbides.
- Steel 40X13 has a fairly high hardenability: parts can be hardened by cooling in oil or air.
- In steel 40Kh13, before the pearlitic transformation of austenite, Cr carbides are precipitated from it23C6. After depletion of austenite in carbon pearlite transformation of austenite occurs.
- The interval of martensitic transformation in steel 40X13 is 270-80 °FROM. When quenched from temperatures 980-1000 °With almost complete transformation of austenite into martensite occurs.
- Intermediate (bainitic) there is no transformation in steel 40X13.
- Tempering hardened steel 40X13 leads to the decomposition of martensite into a ferrite-carbide mixture. With an increase in the tempering temperature, the hardness of steel 40X13 decreases. On vacation in the interval 480-520 °C, a significant decrease in plasticity and impact toughness occurs due to the development of temper brittleness processes.
- Steel 40X13, depending on the specified hardness, is used either after low-temperature tempering at 200-400 °FROM, or after a high holiday at 600-650 °FROM. For intermediate tempering temperatures, a decrease in corrosion resistance is characteristic.
Steel assortment 40X13
The following products are made from 40X13 steel:
- thick sheet according to GOST 7350-77;
- thin sheet according to GOST 5582-75;
- tape and roll according to GOST 4986-78;
- long products according to GOST 5949-75;
- wire according to GOST 18143-72.
Mechanical properties of steel 40X13
- According to GOST 5582-75 steel 40X13 after softening heat treatment in the form of annealing or tempering at 740-800 ° C must have a tensile strength of at least 560 MPa and elongation not less 15 %.
- According to GOST 5949-75 hot rolled hardness, forged, calibrated and ground steel 40X13 in the annealed or tempered condition should be 229-143 NV.
Mechanical properties of steel 40X13 at elevated temperatures
Influence of temperature rise on mechanical properties of 40Kh13 steel after quenching with 1050 °With and leave at 600 °C shown in the table 2.
Steel 40X13 after quenching and low tempering has good corrosion resistance in atmospheric conditions (except for the marine atmosphere), weak solutions of nitric acid at moderate temperatures, river and tap water.
Corrosion resistance of steel 40X13 depends significantly on the quality of the surface of the products. It is recommended to use a ground and polished surface.
Special properties of steel 40X13
When steel 40X13 operates in hydrogen, the maximum permissible atmospheric parameters are 600 °With and 80 MPa.
Density of steel 40X13 - 7,68 g / cm3.
Technological parameters of steel 40X13
Steel 40X13 has good workability in hot plastic deformation. The temperature range of hot plastic deformation is from 1100 to 850 °FROM. Steel 40X13 is prone to formation at high rates of heating and cooling. Therefore, heating for rolling and forging is carried out slowly until 830 °FROM. After hot deformation, slow cooling is applied.
Cold plastic deformation of steel 40X13 is limited. Annealing is used as a softening heat treatment after hot or holonic plastic deformation. 750-800 °With subsequent cooling with an oven to 500 °FROM and further on air. The final heat treatment is hardening with 950-1000 °With cooling in oil or air for a given hardness and corrosion resistance.
Ульянин Е. A. Corrosive steels and alloys, 1991.
Gulyaev A. P. Metallurgy, 1986.