Spring-spring steels are characterized by a fairly high modulus of elasticity. This indicator is possessed by carbon and alloyed metal grades.
Alloy and carbon materials
This type of material is used for the production of rigid (force) elastic elements. The reason for this particular application was that the high modulus of elasticity of this steel severely limits the elastic deformation of the part, which will be produced from spring-spring steel. It is also important to note that this type of product is high-tech and at the same time quite affordable. In addition to use in auto and tractor manufacturing, this type of material is also widely used for the manufacture of power elements in various devices. Most often, parts that are made of this steel are called by one common name - general purpose spring steels.
In order to ensure the necessary performance of elastic force elements, it is necessary that spring steel has a high limit of not only elasticity, but also endurance, as well as relaxation resistance.
The properties
In order to satisfy such requirements as endurance, resilience and relaxation resistance, materials with a high carbon content are used. The percentage of this substance in the product used should be in the range from 0.5 to 0.7%. It is also important to harden and temper this type of steel . It is necessary to carry out these procedures at temperatures from 420 to 520 degrees Celsius.
It is worth noting that spring steel hardened to martensite has a low coefficient of elasticity. It rises significantly only on vacation, when the troositite structure is formed. The process guarantees an increase in the ductility of steel, as well as its fracture toughness. These two factors are important in order to reduce sensitivity to voltage concentrators, as well as increase the endurance limit of the product. It can be added that isometric quenching for lower bainite is also characterized by positive qualities.
Knives
Spring steel for a knife for some time was the most common material, especially among car owners. The manufacture of sharp objects was really carried out from old springs, which had become unusable for use in a vehicle. The use of knives from such an unusual material was carried out both for various household needs, and for the usual cutting of products in the kitchen. The choice fell on this detail not by chance. There were several reasons why spring steel became the main material for the home-made production of good knives.
The first reason is that due to the poor quality of the roads, such a part as a spring often and quickly deteriorated. Because of this, many car owners had these nodes in abundance. Details just lay in garages. Availability was the first reason.
The second reason is the spring design, which included several sheets of carbon steel. It was from these elements that one could make a pair of solid knives.
The third reason is the high elasticity of spring steel, which allows you to process the material with only a minimal set of tools.
Knife Features
A significant reason why this particular type of steel has become widely used for the manufacture of knives is the composition of the product itself. In production, this composition was called spring-spring steel 65G. As the name implies, this material is widely used for the production of springs, springs, washers, as well as some other details. The cost of this particular steel grade is considered one of the lowest among carbon materials. But at the same time, its characteristics, that is, strength, flexibility and toughness, are at their best. In addition, the hardness of the steel itself has also increased. All these features of carbon metal also played a decisive role in the choice of material for creating knives.
Steel 65G
Spring steel 65G is a structural high-carbon steel that is supplied in accordance with GOST 14959. This brand belongs to the group of spring-spring steels. Two of the most important requirements for this type of steel are high surface strength, as well as increased elasticity. In order to achieve the necessary strength, up to 1% manganese is added to the metal. In addition, in order to achieve all the required indicators, it is necessary to conduct proper heat treatment of parts made from this brand.
The wide and effective use of this type of steel is due to the fact that it belongs to the class of economically alloyed, that is, cheap. The main ingredients of this product are components such as:
- carbon, the content of which is from 0.62 to 0.7%;
- manganese, the content of which does not exceed from 0.9 to 1.2%;
- the content of chromium and nickel in the composition from 0.25 to 0.3%.
Other components that make up the steel are sulfur, copper, phosphorus, etc. These are impurities, the percentage of which is regulated by the state standard.
Heat treatment
There are several heat treatment modes for this type of steel. Any of them is selected in accordance with the production requirements that apply to the finished product. Most often, two methods of heat treatment are used, which guarantee the necessary properties from a chemical and physical point of view. These methods include normalization and hardening followed by tempering.
When conducting heat treatment, it is necessary to choose the right temperature parameters, as well as the time that is needed for the operation. To correctly select these characteristics, one should start from what type of steel is used. Since 65G grade material belongs to the hypereutectic type, this product contains austenite, presented as a solid mechanical mixture with a small amount of ferrite. Austenite is a harder material in terms of structure than ferrite. Therefore, for heat treatment of 65G steel, it is necessary to create a lower interval of quenching temperatures. Given this fact, similar indicators for this type of metal range from 800 to 830 degrees Celsius.
Hardening mode
How to harden spring steel? It is necessary to create the desired temperature regime, choose the right time, and also correctly calculate the time and temperature of the vacation. In order to give steel all the necessary characteristics that are set by the future technical conditions for the operation of the part, it is worthwhile to conduct the necessary hardening. To select the appropriate mode for carrying out this procedure, they rely on such characteristics:
- Important is not only the hardening method, but also the equipment that is used to heat the steel.
- Choose the necessary temperature regime of hardening.
- Choose a suitable time period for steel hardening.
- Choose the right environment for the hardening process.
- It is also important to choose the right technology for cooling the part after the hardening process.
Steel grade
The supply of steel for the manufacture of springs is carried out in the form of strips. After that, blanks are cut from it, quenched, released and collected in the form of packets. Grades of spring-spring steel, such as 65, 70, 75, 80, etc., are characterized by the fact that their relaxation resistance is small, especially this drawback is noticeable when the part is heated. These steel grades cannot be used to work in an environment whose temperature exceeds 100 degrees Celsius.
There are cheap siliceous grades 552, 60C2, 70. They are used for the manufacture of springs or springs, the thickness of which will not exceed 18 mm.
Higher-grade steel grades include 50, 50. Compared with silicomanganese and siliceous materials, the temperature is much higher during tempering - about 520 degrees. Due to this processing procedure, these steel grades are characterized by high heat resistance, as well as low sensitivity to notching.