Characteristics of material steel 20ХН3А

Application

So, let's start with the most obvious, in our opinion, but no less important question, namely, what 20khn3a steel is used for. Most often, parts are made from this type of steel, which are subsequently subjected to a carburizing process. This means that such parts will need to combine surface hardness and internal plasticity in the future.

Such requirements are usually imposed on products that, during their operation, will in one way or another be subject to loads, including shock. In this case, the hard surface layer will prevent deformation of the part, and the inner soft layer will take on all the physical consequences of the impact and absorb them without harm to the part. This category includes shafts, studs, bolts, gears and bushings, and much more.

Steel grade 20ХН

Chemical composition

Mechanical properties

Mechanical properties depending on the section

Mechanical properties of the rod

Technological properties

Critical point temperature

Impact strength

Hardness

Endurance limit

Hardenability

Steel Cementation

And since we mentioned the carburization of steel 20khn3a, it’s worth telling you, albeit briefly, about what this process is. The very essence of the process is to saturate obviously low-carbon (usually up to 0.2% C) steel with this same carbon, thereby giving it hardness. However, one must understand that such a process will carbonize only the surface layer of the metal product in the range from 0.5 to 2 millimeters, leaving the middle soft and pliable.

The carburization process itself, which gives 20khn3a steel the characteristics of increased strength, occurs at elevated temperatures (850-950 °C) in a carbon-containing environment. Enterprises usually use gas carburization using methane or carbon monoxide, but a similar procedure can be carried out using charcoal or sodium carbonate solution.

When heated to the above-mentioned temperature, steel enters the active phase and absorbs carbon from the external environment. However, this process is quite slow. To carburize a layer of one millimeter, it takes from 4 to 10 hours, depending on the carburization method.

Legend

Mechanical properties

Chemical composition

As is known, the characteristics of absolutely all grades of steel depend primarily on the alloying elements in its final composition. It is the addition of chemical elements that ultimately gives steel the necessary properties, be it hardness or, conversely, ductility, resistance to corrosion or shock loads. This is why it is sometimes so important to study the composition of steel. The easiest way to do this is to look at the corresponding GOST. Steel 20khn3a is mentioned in many GOST standards, therefore, in order to make your search easier, we will provide a list of all elements and the values ​​of their mass fraction in the composition of the steel right in this article.

It looks like this:

• Carbon – 0.2%.
• Chromium – 0.75%.
• Nickel – 2.95%.
• Manganese – 0.45%.
• Silicon – 0.27%.
• Copper – 0.3%.
• Sulfur and phosphorus – 0.025%.

Structural alloy steel 20ХН

Brand 20ХН – purpose

Structural alloy chromium-nickel steel 20ХН is used for the manufacture of parts with moderate hardenability and high toughness - hexagons, circles, squares, strips, bushings, gears, fasteners, pins, and other products.

Steel 20ХН - domestic analogues

Characteristics

Material 20ХН – technological properties

Brand 20ХН – chemical composition

Mass fraction of elements no more than, %:

Steel 20ХН – mechanical properties

Material 20ХН – hardness, MPa

Brand 20ХН – temperature of critical points, 0С

Steel 20ХН – impact strength, J/cm2

Material 20ХН – exact and closest foreign analogues

Characteristics

All the basic properties of any steel grade are inevitably studied, further checked and ultimately entered into a regulatory and technical document, that is, GOST. For example, in order to better understand the topic of the article and the topic of metallurgy in general, we advise you to pay attention to GOST 8479-70, as well as GOST 4543-71, 7417-75 and 103-2006. While studying these documents, you will most likely come across incomprehensible terms and designations, which you would also do well to familiarize yourself with so that studying such documents is not so difficult.

However, we are a little distracted from the topic. Since we have already become familiar with the chemical composition of 20khn3a steel, we can quite accurately determine its main properties. This steel, thanks to the admixtures of nickel, chromium and copper, is endowed with good corrosion resistance, which is very important for many parts made from this type of steel. In addition, the increased nickel content increases hardenability, which will undoubtedly facilitate the carburization process.

Carbon is primarily responsible for hardness here, which, undoubtedly, is extremely small to ensure the initial hardness of 20khn3a steel. Silicon and chromium improve the situation slightly, but their effect on the strength and hardness of steel is extremely insignificant.

Properties of steel grade 20ХН3А

The specific gravity of the material is 7850 kg/m3. The final product made of steel of this grade undergoes heat treatment in the form of quenching and tempering.

The primary forging temperature reaches 1220°C, the final temperature is 800°C. Workpieces with a cross-section of up to 100 mm are cooled in the open air. With a cross section of more than 101 mm, the part is cooled in special pits.

The Brinell hardness of the material reaches 10 -1 = 255 MPa. Critical points are reached at temperatures:

• Ac1 = 730°
• Ac3(Acm) = 810°
• Ar3(Arcm) = 700°
• Ar1 = 615°
• Mn = 340°

Machinability is available in the hot-rolled state, with a Brinell hardness of 177 units and a tensile strength of 610 MPa.

The material is classified as having limited weldability. The following welding methods are available for it:

• manual arc (RDS);
• argon-arc submerged arc (ASA).

The alloy is flake-sensitive and has a tendency to temper brittleness.

Characteristics of material steel 20ХН3А

Chemical composition in % of material 20ХН3А

Temperature of critical points of material 20ХН3А

Mechanical properties at T=200C of material 20ХН3А

Physical properties of material 20ХН3А

Technological properties of material 20ХН3А

Designations

Mechanical properties:

Physical properties:

Weldability:

Manufacturing and properties of the most common products made of steel 20ХН3А

Rods GOST 4543-71

These parts are hardened in oil at a temperature of 820°C, then they are tempered in water or oil at a thermometer reading of +500°C. The cross-section of such products is 15 mm. The conditional yield strength reaches 735 MPa.

The parts are quite durable. Their temporary tensile strength can withstand up to 930 MPa. Relative elongation after rupture can reach 12%, narrowing – 55%.

Forgings GOST 8479-70

These products are hardened and tempered. Their cross-sectional diameter reaches 100 mm. The proof strength varies from 590 to 685 MPa. The ultimate tensile strength of products occurs at 735-835 MPa. The relative elongation of the walls of the product after rupture is 13-14%, narrowing 42-45%.