440 steel - stainless steel. Steel 440: Characteristics

Steel is a compound of iron and carbon. The types of this material are determined not by the ratio of the main components, but based on impurities and additives that impart different properties and characteristics to the product.

Types of steel, according to pricing, can be divided into sub-groups: cheap, popular and expensive. Everything depends on the purpose of the material, the difficulties of its production. And there is no uniquely bad or good alloy, because 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

High-quality steel should be characterized simultaneously by wear resistance, strength, elasticity, plasticity, rigidity, anti-corrosion ability and endurance sharpening. In practice, almost all of the above properties contradict each other. One of the main elements of the alloy, responsible for hardness and rigidity, is carbon. To compounds with a high content are those in which the concentration of a given chemical element is more than 0.5%. The property of durability and low propensity to corrosion empowers chrome steel. If its level is more than 13%, then this is a stainless product.

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

To make the products of this material not brittle and fragile and at the same time are resistant to heat, molybdenum is added to the compound. In this case, the alloy is called quenching in air.

Helps reduce corrosion risks and gives firmness to nickel. 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 mainly for the manufacture of knives, building structures. A distinctive feature of this alloy is its resistance to corrosion and high strength. Also 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, 440B, 440C, with the 440A series being softer than others, and 440C being harder. However, the minus 440C is brittleness and relatively low resistance to rust in relation to 440A and 440V. It turns out that with prolonged contact with moisture or corrosive media, corrosion may appear. Although additional properties that prevent rust, are given to this alloy due to a 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 of 440 steel

Steel 440, whose characteristics directly depend on the chemical composition, according to the series, contains the elements listed in the table below.

As can be seen from the table, the lowest carbon content in the 440A series, the highest is 440C, that is, the last grade is stronger than all, and the first is the most resistant to corrosion. Although all the series of this brand are quite high quality and tolerate loads well.

Physical properties and heat treatment of stainless steel 440

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

• The density of the material is 7650 kg / cu. M;
• Modulus of elasticity - 200 GPa;
• Thermal conductivity - 242 W / m kb;
• Specific heat - 460 J / kg.kb .;
• The electrical resistivity is 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; 440V - 10.3; 440C - 11.7.

The thermal treatment of this material goes through the following stages:

• annealing;
• Hardening;
• Vacation.

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

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

Leave passes at a temperature of + 150-370 degrees, due to which the material is given the necessary hardness. Among the varieties of material such as steel 440, the mechanical properties are the best in the 440C brand. This alloy is the most expensive and reliable. It defines the standard of product quality.

Applications of steel 440

Stainless steel 440 is used in most cases for making knives. Rolled this alloy is designed for building products that have welded or other connections.

Sheets of finished products are available in thicknesses from 4 to 50 mm. 440 steel does not require additional heating and heat treatment when carrying out welding operations. Convenient and reliable alloy for the production of bearings, parts of pipeline valves.

Of the brand 440A produce large ungainly knives, including for underwater work, hunting. Blades from the 440C series have excellent cutting properties and good sharpening time, so this steel is used for the production of elite cutting tools.

You need to know when buying a knife labeled "440", which uses a less expensive alloy - 440A. When using more expensive 440V and 440C connections, manufacturers always pay attention to this.

Alternative stamps

There are a number of alternative brands that 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. Inferior to its characteristics in terms of hardness grade 420. 416 series has increased machinability, but lower reliability.

If you make knives from the brand 440A and its analogs, then such products are suitable for everyday use. Although, it is worth considering the quality of hardening. The company Sog was well proven in this process. The company "Rendel" mainly produces knives from steel 440V.