440 steel - stainless steel. Steel 440: Characteristics

Steel is the compound of iron and carbon.The types of this material are determined not by the ratio of the main components, but on the basis of impurities and additives, which endow the product with different properties and characteristics.

Types of steel, according to the pricing policy, you candivided into subgroups: cheap, popular and expensive. It all depends on the purpose of the material, the difficulties of its production. And there is no uniquely bad or good alloy, since this material contains a whole range of characteristics that meet certain conditions. Specifically, this can be seen if we consider, for example, 440 steel.

Steel Components

Качественная сталь должна характеризоваться at the same time wear resistance, durability, elasticity, plasticity, rigidity, anticorrosive ability and sharpening hold. In practice, almost all of the listed properties contradict each other. One of the main elements of the alloy, responsible for hardness and rigidity, is carbon. Compounds with a high content include those whose concentration of this chemical element is more than 0.5%. The property of wear resistance and low propensity to corrosion gives steel chrome. If its level is more than 13%, then it is a stainless steel product.

Grit, strength, stiffness gives the alloy manganese. It is used at the stage of forging and rolling. This is the so-called deoxidized steel.

To prevent products made from this material from being brittle and brittle and yet resistant to heat, molybdenum is added to the compound. In this case, the alloy is called quenched in air.

Helps reduce the risk of corrosion and gives nickel hardness. The property of the fortress provides the material with silicon. Tungsten and vanadium give the alloy strength and durability.

Features of steel grade 440

440 steel refers to stainless materials.It is used primarily for the manufacture of knives, building structures. A distinctive feature of this alloy is corrosion resistance and high strength. Also the advantage of this series is the resistance to the action of environmental factors, water, food, weak acids and alkalis.

Steel grade 440 includes subspecies 440A, 440V,440C, with the 440A series being softer than others, and 440C being harder. However, the minus 440C is brittleness and relatively low rust resistance with respect to 440A and 440V. It turns out that prolonged contact with moisture or aggressive media may cause corrosion. Although additional properties that prevent rust, attached to this alloy due to the smooth polished surface.

It is not recommended to use 440 steel at a temperature higher than its heating during tempering, since in this case the mechanical properties of the alloy will be lost.

Chemical composition 440 steel

Steel 440, the characteristics of which directly depend on the chemical composition, according to the series, contains the elements shown in the table below.

As can be seen from the table, the lowest contentcarbon in the 440A series, the highest - 440C, that is, the last mark is the strongest of all, and the first is the most resistant to corrosion. Although all the series of this brand are quite high quality and tolerate load.

Physical properties and heat treatment of stainless steel 440

Steel 440 physical characteristics for series A, B and C has the following:

• material density - 7650 kg / cu. m;
• elastic modulus - 200 GPa;
• thermal conductivity - 242 W / m KB .;
• specific heat capacity - 460 J / kg.kb .;
• electrical resistivity - 600.

The hardness of steel 440 varies between 56-58 units.

The average coefficient of thermal expansion, which is measured in mm / m / degrees Celsius, for the 440A series is 10.1; 440B - 10.3; 440C - 11.7.

Heat treatment of this material passes the following stages:

• annealing;
• quenching;
• vacation.

Annealing takes place at a temperature of + 850-900 degreescentigrade, followed by a constant decrease to _600. Cooling occurs by air. Then - the procedure of decaying annealing at 735-785 degrees and cooling in the furnace.

Hardening is carried out at + 1010-1065 degrees Celsius. Quenching - using warm oil or air.

Vacation takes place at a temperature of + 150-370degrees, thanks to which the material is given the necessary hardness. Among the varieties of a material such as steel 440, the mechanical impact characteristics are the best for the 440C grade. This alloy is the most expensive and reliable. It defines the quality standard of products.

440 steel application areas

In most cases, stainless steel 440 is used to make knives. Rental of this alloy is intended for construction products that have welded or other compounds.

Листы готовой продукции выпускаются толщиной от 4 up to 50 mm. 440 steel does not require additional heating and heat treatment during welding. Convenient and reliable alloy for the production of bearings, parts of pipeline valves.

From brand 440A produce large awkwardknives, including for underwater work, hunting. Blades from the 440C series have excellent cutting properties and good sharpening shutter speed, therefore this steel is used for the production of elite cutting tools.

Need to know when buying a knife marked "440",that less expensive alloy is used here - 440A. In the case of using more expensive 440B and 440C connections, manufacturers always pay attention to this.

Alternative brands

There are a number of alternative brands thatYou can replace this alloy. For example, the 440A / B series has additional properties that improve corrosion resistance. Steel 440F has a higher workability with similar strength. The brand 420 yields the characteristics on hardness. 416 a series has the increased workability, but lower reliability.

Если изготавливать ножи из марки 440А и ее analogues, such products are suitable for everyday use. Although, it is necessary to take into account the quality of hardening. Well established in this process firm Sog. Rendell mainly manufactures 440B steel knives.