High-alloy steel: description, welding technology, marking and features

In our time it is difficult enough to overestimate the importance of products of metallurgy, which are widely used in industry, construction, manufacturing of household utensils, household items. But special attention deserves alloy steel, without which a large number of industries (machine building, petrochemical, energy, food, the manufacture of special structures, whose main purpose is to work in aggressive conditions) could not perform their basic functions.

A logical question arises: what is alloy steel, its alloys? What is the classification of alloying elements? What are the main characteristics and properties of high-alloy steel? We will try to answer these and some other questions in our article as fully as possible.

What is alloy steel?

Let's first find out what the metal is. Alloyed steel is an alloy of iron with carbon, which has in its composition special elements that affect the main mechanical or physical properties of the final products of the metallurgical industry. Elements that are added to the basic composition of the alloy are called alloying. Chromium, nickel, vanadium, manganese, copper - their main group.

Types of steel

There is a classification of alloying elements, which is based on their percentage content in the alloy:

• High-alloy steel - 10-50%.
• Medium - weighted - 2.5-10%.
• Low - alloy - up to 2,5%.

Types: high-alloy steels, alloys

Let's consider one more interesting moment. High-alloy steel and its alloys are also classified. Each of the following species is used in certain conditions:

• Heat-resistant or heat-resistant steel.
• Corrosion-resistant.

Based on the percentage content of the alloying element, the following types are distinguished:

• Chromo-manganese steel.
• Chromium-nickel.
• Chrome-plated.

Use of high-alloy steels

Where is this metal used? High-alloy steels and their alloys are integral components in the production of various products. The following industries can not do without using them:

• Chemical.
• Oil industry.
• Mechanical engineering.
• Building.
• Manufacturing of structures, the main purpose of which is to work in aggressive conditions (high temperature, swings).

Addition of alloying elements allows to achieve certain mechanical properties. Therefore, high-alloy steel is used as a cold-resistant component. Especially often this metal is found in engineering. The most popular are high-alloyed austenitic steels, in which the alloyed component occupies about 55%, and the rest is iron, chromium (about 18%), nickel (8%). Alloying components of similar composition determine the further purpose of the manufactured products.

Use of corrosion-resistant steels

Corrosion-resistant high-alloy steels are used in a gaseous medium or alkaline acid. Their characteristic difference is the reduced content of carbon - approximately 0.12%. Further alloying and heat treatment make it possible to obtain a special alloy that can withstand the aggressive conditions of a gas or liquid metal medium.

The use of steels containing tungsten or molybdenum at the level of 7% and boron allows working at temperatures up to 1100 degrees. Tungsten and molybdenum are elements that relate to hardeners. In order to increase the scale resistance of the products, silicon or aluminum is added as alloying elements. Such designs can be used as heating elements or furnaces.

Main characteristics of metal

High-alloy steel has properties and characteristics that make it possible to use products more widely. Such steels have the following characteristics:

• Strength (achieved through heat treatment).
• Corrosion resistance.
• Resistance to deformation processes.
• Plasticity (in comparison with carbon steel, plasticity is many times greater).
• Nonmagnitude (steel used in engineering).
• Elasticity.
• Strength.
• Weldability.

Due to the fact that the formula of the alloy is different, the properties are varied. The structure is easily changed due to heat treatment and alloying components. Thus, you can get the properties that are required by the terms of the project. For example, high-alloyed 18% chromium steel can have nickel in the composition, which makes it possible to obtain corrosion resistance and cold-brittleness.

Welding of high-alloy steels allows obtaining products that can be used in any climatic conditions. Thus, the method of stamping allows the final product to be used at critically low temperatures - up to minus 253 degrees Celsius. Special treatment with silicon allows to obtain ferrosilides, which can work in strong acids (nitrogen, phosphoric and others).

High-alloy steel has a hardness, high abrasion. So, acid-resistant materials are - C15 and C17, and chromium, vanadium and manganese increase the wear resistance of the alloy.

Types of high-alloy steels by thermal properties

Based on thermal characteristics, there is the following classification:

• Platinum (EN42) - is used for the production of electrodes, which are used in incandescent lamps. This is because the expansion coefficient is the same as for glass.
• Elinvar (X8N36) - ideal for clock springs and measuring instruments. This is because the modulus of elasticity is constant and does not degrade at temperatures from -50 to +100 degrees Celsius.
• Invar (I36) - is used for the production of standards, calibration elements, since the expansion coefficient is zero.

The intrinsic property of corrosion steel (only high-alloy stainless steel) is magnetic. Therefore, non-magnetic and magnetic types of such metals are distinguished. The former are subdivided into magnetically soft and magnetically hard subspecies, and the latter have cobalt, chromium.

GOST: high-alloy steels

Requirements for such strong metals and heat-resistant alloys are regulated by special regulations, namely GOST 5632-72.

Grades of high-alloy steels

The most popular and known are the following steel grades :

• Ferritic: 15Х28, 12Х17, 08Х18Т1, 15Х25Т, 08Х18Тч, 10Х13СЮ.
• Martensitic: 15Х11МФ, 40Х9С2, 18Х11МНФБ, 40Х10С2М, 95Х18, 25Х13Н2, 20Х17Н2, 13Х11Н2В2МФ, 40Х13, 20Х13, 20Х17Н2, 13Х14Н3В2ФР.
• Austenitic-martensitic: 07Х16Н6, 08Х17Н5М3, 08Х17Н6Т, 09Х17Н7Ю1.
• Austenitic-ferritic: 08Х21Н6М2Т, 08Х22Н6Т, 08Х20Н14С2, 20Х23Н13, 12Х21Н5Т, 03Х22Н6М2.
• Martensitno-ferrite: 12Х13, 18Х12ВМБФР, 14Х17Н2, 15Х12ВНМФ.
• Austenitic: 05Х18Н10Т, 45Х22Н4М3, 45Х14НМВ2М, 10Х14Г14Н4Т, 03Х18Н13М2Б, 12Х18Н12Т, 03Х18Н12, 03Х16Н15М3Б, 10Х11Н23Т3МР, 20Х23Н18, 10Х11Н20Т2Р, 12Х18Н9Т, 12Х18Н9, 20Х25Н20С2.

Application of alloying steel grades:

• 40X13, 30X13 - used for carburetor needles, springs for transport, surgical instruments.
• 12Х17 - a brand of high-alloy steel, used for making kitchen utensils or household items.
• 20Х13, 12Х13, 08Х13 - are used for manufacturing elements of hydraulic installations, structures that operate under mildly aggressive conditions.
• 95Х18 - used for the production of high-pressure ball bearings.