Soldering steel has been known since ancient times. This method of combining metals was common in ancient Rome, ancient Greece, ancient Egypt. Soldering is the process of forming permanent joints of metals between which solder is injected. This molten material fills the space between the two parts, thereby firmly connecting them. After complete solidification of the solder, a strong one-piece connection is formed.
High-temperature brazing of steel is performed when the solder is heated to a melting point above 450 ° C.
There are several classifications of soldering. Depending on the melting point of the solder, the process of joining parts can be divided into high-temperature and low-temperature.
High-temperature soldering occurs when the solder is heated, for example, with a gas torch to a melting point above 450 ° C. This method results in bonds that can withstand a large load. At high-temperature soldering, hermetic and vacuum-tight connections are formed, capable of operating at high pressure.
Low-temperature soldering can be used to connect small parts and thin films. This method allows you to bind dissimilar metals. This type of soldering is quite simple in execution.
Compound carbon low alloyed alloys
Tools required for soldering.
Low carbon steels are general purpose steels. They are widely used because of their low prices in shipbuilding, bridge construction, boiler houses and other special areas.
Low-carbon steel brazing is the simplest process to join products. For this you can use various solders. A chemically unstable oxide film is formed on the surface of these alloys, which is not difficult to restore and dissolve in the fluxes.
Copper or its derivatives are often the binding element. Lead or tin-lead binders are less commonly used. The protective environment in such a process is a reducing atmosphere.Back to table of contents
Construction Steel Coupling
Structural steel with chromium content. An example would be corrosion-resistant, heat-resistant or high-strength alloys. The combination of such metals has a number of difficulties. Due to the presence of chromium in their composition, it is very difficult to remove a chemically resistant film. Due to this fact, the production of permanent connection is made using active fluxes. The gas medium in this case is a compound of boron trifluoride and nitrogen (or argon). Such a process can be carried out in a vacuum.
The soldering scheme became hard solder.
When carrying out the soldering process, it is best to use certain devices designed to control the characteristics and composition of the protective atmosphere, as well as the degree of vacuum. This is a fairly expensive tooling. To minimize the cost of these devices most often on the surface, prepared for the connection, put special compounds. An example of such a coating can be copper, zinc or nickel. These compounds protect the steel from the formation of iron oxides on its surface, prevent alloying components from burning out.
Compound structural steels should not be made at temperatures above 1100 ° C. When this indicator is exceeded, the ductility decreases in corrosion-resistant steels, strength characteristics deteriorate in heat-resistant steels, and brittleness increases in high-strength steels.
Nickel, copper, silver and other metals are most often used as solder in such processes.Back to table of contents
Connection of heat-resistant steels
The procedure for the soldering of steel pipes.
In the technique often used heat-resistant alloys, consisting of one phase and more. They consist of combinations of nickel-chromium, nickel-iron-chromium or other metals. These alloys are characterized by increased strength and heat resistance, resistant to corrosion.
The process of combining these metals occurs at a temperature of about 1100-1150 ° C. Excess of this temperature can lead to a deterioration of ductility, as well as burnout.
If the alloy contains refractory components, then upon receipt of permanent connections, a stable oxide film is formed on the surface of the metals. These alloying additives must first be removed with acid-base solutions. After that, the metal surface is treated with nickel.
Copper or nickel is used as binding elements.
The protective medium in such a soldering process is a neutral gaseous medium or vacuum without the use of fluxes.Back to table of contents
Compound tool and hard alloys
Tool steels are very durable, hard, have low cost and high availability. Because of these positive characteristics, this type of alloy has gained immense popularity in the production of various tools.
Scheme of capillary soldering steel.
Soldering of this type of alloy produced in the same way as low-carbon. However, at heating temperatures above 200 ° C, hardness of these metals decreases, the heat resistance of the material decreases. This disadvantage is eliminated by the addition of tungsten to tool steels. The use of this additive raises the soldering temperature to 550-600 ° C.
In this case, nickel or ferroalloys will serve as solders. Soldering of tool steels should be carried out by induction using boride fluoride fluxes. Soldering in salt baths or gas-flame furnaces is suitable for this process.
For the connection of hard alloys, the same fluxes are used as for tool steels, and in this case copper-zinc alloys with the addition of manganese, nickel or aluminum, less often copper-manganese alloys will serve as solders. With this type of soldering, a mechanized or automatic method of heating the metal is used.Back to table of contents
Steel soldering technology
Independent connection of steel parts using soldering does not cause much difficulty. Steel products can be soldered using ordinary tin.
The simplest type of soldering occurs in the sequence:
- Cleaning products from contamination.
- Mechanical cleaning of the surface of the oxide film with a sanding cloth or a metal brush.
- Surface degreasing with sodium carbonate, caustic soda, acetone or other solvent.
- The junction of steel parts is coated with flux.
- Details are collected and recorded.
- The product heats up. The connecting seam heats up, at the same time it is necessary to apply solder to it. When the required temperature is reached, the solder will begin to melt.
- After the end of the soldering process, the seam is cleaned of the flux residues and solder.
It must be remembered that the soldering temperature depends on the solder used. Heated to a higher temperature should not be.
If you do not distribute the solder on the surface of the connecting seam, the reasons may be:
- insufficient cleaning of the metal surface;
- use of flux that is not suitable for this type of soldering;
- use of the wrong type of binding element;
- insufficient warm-up temperature.
Soldering - one of the most common processes for obtaining one-piece connection parts. The result of such an impact will be a durable product. The easiest way to solder steel can be done with your own hands, the main thing - to know some of the features.