Alloy steel

When choosing a material for the manufacture of a metal product, several characteristics, including its rigidity modulus, must be taken into account. This structurally insensitive indicator depends only on the nature of the material from which the force elements are made - stringers, frames, flat plates, etc.

The highest rigidity module has steel, which in its chemical composition is of two kinds. Firstly, it is alloy steel, into which alloying elements are specially added to obtain any necessary properties.

The main elements that affect the property of steel are carbon, silicon and manganese. Carbon with increasing its content makes the steel stronger and harder, while reducing its plasticity. Silicon is introduced as a deoxidizer, but if it contains more than one percent, weldability of steel deteriorates much : the weld is made brittle. And an element such as manganese increases the cold-brittleness and toughness of steel, also being a good deoxidizer.

As a rule, in addition to iron and carbon, any one component is added, so the alloyed steel is classified as a three-component, four-component, etc. It sometimes differs by the name of the alloying element, for example, chromium, chromium-nickel, chromium-nickel-molybdenum, etc.

Alloyed steel contains more than one percent chromium or nickel. If more than 0.5% of vanadium, titanium, molybdenum, niobium, nitrogen, copper, etc. are present in it, then it is considered to be alloyed with these elements.

Depending on the number of added components, alloy steel is divided into the following subclasses:

- High-alloy steel, in which the total content of alloying elements is not less than ten percent;

- medium-alloyed - no more than eight percent;

- low-alloy steel, in which only one element is added with an upper limit of not more than two percent.

Usually alloying elements significantly increase the cost of steel, especially since some added elements are in themselves deficit expensive metals. Proceeding from this, their addition to steel should be necessarily justified.

Alloyed steel has the following markings: the first two digits show the carbon content (hundredths of a percent), the letters conditionally indicate the added alloying element, the figure after them is the percentage of this element. The letter "A", which stands at the end of the marking, means that this steel is of high quality with a reduced content of phosphorus and sulfur.

Another kind of steel in terms of chemical composition is carbonaceous. Its because of the simplicity of production and cheapness is more often used in many industries.

One of the purposes of steel is its use in the manufacture of measuring and cutting tools, machine parts, stamps with cold and hot deformation.

Instrumental steel is both alloyed and carbonaceous, and depending on the standards regulated by GOST, for each specific metal product it is necessary to use steel having a certain chemical composition.

For example, for surgical instruments, drills, chisels, hammers, screwdrivers, saws, mills, etc., steel of a certain category is used - high-alloy, high-speed. It has a high hardness, heat resistance and wear resistance. These unique properties are obtained by special alloying with the addition of tungsten carbide, as well as complex heat treatment.

For hammer, cold and hot dies, molds, etc., steel of such brands as X6VF, 9X, 5XNM, etc. is used.