In this article, we will talk about the all-known brand of HVG steel, discuss its purpose, application, touch upon the topic of similar steels produced abroad, and describe the technology of heat treatment of this alloy.
Using
And in order for all the material presented below to become more clear to you, it is worth starting with why this alloy is used at all. Due to its special characteristics, the use of CVG steel is most often observed in the manufacture of high-precision measuring tools, such as, for example, calipers familiar to many, as well as long cutting tools, such as taps, broaches, drills or reamers.
Such a list allows us to safely say that CVG is a high-strength steel suitable for processing other, softer metal breeds. Also, do not forget that with an increase in the length of the product, the chance of its deformation increases. And since long products are made from the HVG steel grade, we can conclude that it has an increased resistance to deformation.
GOST
To learn more about what constitutes the steel we are interested in, we turn to the regulatory documents that mark the HVG brand as alloy steel. Even this seemingly very short wording gives us some information. The fact is that tool steel is called that steel whose carbon content exceeds 0.7%. Alloy steel is an alloy of iron, carbon and some other additives designed to improve the structure of steel.
Oddly enough, but we can learn a little about the alloying elements present in the composition of CVG. To do this, refer to the GOST system, where it is indicated that each such element is assigned a specific letter denoting it. Thus, we become aware that the composition of HVG steel includes:
- X is chrome;
- B - tungsten;
- G is manganese.
Structure
Characteristics and use of CVG steel are interrelated phenomena. The alloy will not be in demand if its mechanical and physical properties do not meet specified standards. In turn, the properties of steel are set by introducing various elements from the periodic table into its composition. Therefore, it is very important to pay attention to the chemical composition of the described alloy in order to better understand the limits of its capabilities.
It looks as follows (only average values are indicated in the list, indicating the mass fraction of all elements):
- carbon - 9.5%;
- silicon - 0.25%;
- Manganese - 0.95%;
- nickel - up to 0.4%;
- chromium - 1%;
- tungsten - 1.4%;
- copper - up to 0.3%.
In addition to the above additives, the alloy also contains so-called harmful ligature elements, such as sulfur and phosphorus, but their mass fraction does not exceed 0.03%, which means that their detrimental effect on the properties of steel is insignificant.
Analogs and substitutes
We are sure that for many it has ceased to be a secret that the named alloy is very popular and necessary in its field of application. The characteristics of CVG steel in this case are not the result of a successful combination of circumstances, but the result of the work of scientists who created the necessary formula. And in view of the high demand for this or a similar formula, it is successfully applied not only in our homeland, but also beyond its borders.
We can provide a small list of similar or just as similar as possible steel grades used in other countries of the world.
- United States of America - 01 or T31507;
- China - CrWMn;
- Europe - 107WCr5;
- Japan - SKS2, SKS3, SKSA.
Technology
In the event that a sample of HVG steel falls into your hands and you decide to make something out of it, some knowledge in the field of metalworking will be very useful to you. Particular attention should be paid to temperature. Indeed, depending on what temperature regime you use for processing, the characteristics and use of CVG steel at the end of the process can change greatly. To protect you from this, below we describe the main technological processes associated with heat treatment, and recommendations for their implementation.
Annealing. It is produced at the very beginning, that is, before any mechanical processing of the product. Annealing is designed to level the initial hardness of the alloy and facilitate subsequent machining. For HVG steel, annealing occurs at a temperature of 800 ° followed by a decrease in temperature at a rate of 50 ° / hour and up to 500 ° . After the product cools to room temperature in air.
Forging. The goal of this process is to give the workpiece the desired shape. In this case, it is very important not to overheat or not to warm the steel. This threatens the formation of internal and / or external defects, as well as a change in the structure of the alloy at the cellular level for the worse. Therefore, forging the workpiece is recommended in the temperature range from 1070 to 860 ° C.
Quenching. A procedure consisting of two processes: heating to a certain temperature and subsequent sharp decrease in temperature. Such a procedure greatly increases the hardness of steel, but reduces its ductility, which makes it brittle. Hardening of HVG steel is carried out by heating to 850 ° C, subsequent immersion in oil and cooling in it to a mark of 200 ° C. Further, the workpiece cools in the air.
Vacation A simple, but rather important process, designed to remove excessive stress in the metal, reduce brittleness and increase ductility. It is carried out at a temperature of 200 ° C for two hours. The final hardness of the steel will be within 63 units of the Rockwell scale.