Borax in working with metals is primarily associated with flux mixtures, which are indispensable for soldering or forging. Borax is sold in the market in powder form. Its value and irreplaceability are determined by its melting point, which reaches 800 - 900°C. When heated, it turns into a glassy solidified mixture, which provides excellent protection for the work area. In addition to this, borax powder is highly soluble in water. All technical characteristics are described in a separate standard GOST 8429-77 called “Technical Borax”.
What and why is metal sprinkled during forging?
Since at a temperature above the start of forging, intense scale formation occurs and the metal can be burned, then to reduce scale, facilitate its removal and protect the metal from burning, the workpiece is sprinkled with flux. Flux is sprinkled onto the workpiece during the period of heating it to a temperature of 950 ... 1050 ° C.
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About tetraborate and decahydrate
Borax has a serious scientific name because it is nothing more than a combination of a weak acid and a strong base. The name is difficult to remember the first time: sodium tetraborate decahydrate.
This mixture, which cannot be called explosive, is part of all effective fluxes and slag mixtures for forging or soldering complex and capricious metals such as copper, its alloys, cast iron, and steel.
Flux for forge welding is a special technological merit of borax, which needs to be discussed separately.
Warm it up thoroughly
The parts are heated in furnaces or furnaces. The amount of fuel must be precisely calculated - no more and no less. The best fuel for forging is charcoal and coke. But in practice, ordinary coal is more often used.
Metal parts are loaded into the forge only after the coal has completely burned out, so that sulfur is removed from it, the presence of which has a bad effect on the quality of the compound.
The heating temperature of the parts must be higher than the level at which forging begins. The level of heating temperature in figures depends on the percentage of carbon in the steel: the lower its content in the alloy, the higher the heating temperature must be raised to melt.
For low-carbon steel, heating should be no lower than 1350 - 1370°C, the distinguishing feature is the shining white color of the metal. If the steel contains a high proportion of carbon, heating to about 1150°C is sufficient, the color will then have a yellow tint.
Forge welding flux is added for protection. It's all about the abundant formation of scale due to heating. Flux mixtures protect against this. Flux for forge welding is poured at a precisely designated moment - when the heating level is between 950°C and 1050°C.
The basis of the mixture is fine clean river sand with the addition of 10% borax after good calcination. Borax in sand promotes good slag formation and easy cleaning of metal from impurities in the future.
The thickness of the layer matters: if it is too thick, heating the parts will reduce speed and quality. Therefore, flux for forge welding is poured in an even and thin layer. The addition of borax to the flux mixture is especially important and necessary if low-quality coal is used.
Table of norms for borax.
The flux mixture forms slag, which can drain from the metal workpiece, which is very undesirable. To prevent this, add additional portions of sand to the workpieces - carefully and in moderate quantities.
Iron filings of a soft consistency or ferromanganese are an excellent partner for borax. Sawdust is capable of absorbing carbon from the metal surface under high temperature conditions, thereby significantly improving the quality of the welding process.
If you need to weld parts from different metals or steel grades, then first of all, the metal with a lower proportion of carbon is heated due to its higher melting point. And only then do they begin to work with the second part, the metal of which contains a higher percentage of carbon.
Classification
Fluxes are a large group of multifunctional mixtures. They differ in a number of characteristics that form the basis of the classification. Classes are conditional.
According to the method of production, compositions are divided into mixtures obtained by fusion, mechanical mixing and gluing. The latter compositions are called ceramic.
Welding fluxes are transparent, similar to glass, and porous, opaque, similar to pumice. For obvious reasons, the density of the porous composition is less than that of the glassy one. Melting is carried out in furnaces at temperatures reaching 1500 °C.
Inorganic substances and their mixtures are subjected to fusion. Most often used:
- silicon oxides (silica);
- samples of manganese ores;
- fluorite (fluorspar);
- magnesium carbonate (caustic magnesite).
The melts are poured into the solution. After hardening, this welding flux forms granules. Hydrophilic substances that tend to absorb water are granulated dry according to a separate technological scheme.
Bonded welding fluxes, similar to ceramics, are used widely, much more often than mechanical powders. Ceramics does not react to rust residues, scale in the working area, or the presence of traces of water there. If the ceramic mixture is added to the vitreous mixture, you can get a perfect seam even on uncleaned metal.
Fluxes have different chemical natures. They consist of oxides, salts, mixtures of oxides and salts.
Safety and storage rules for borax
The forging drill does not pose any particular danger from the point of view of explosions or fires. Moderate toxicity is observed due to the boric acid content. Borax can enter the body through the respiratory tract in the form of dust or aerosol spray, as a result of which the mucous membranes can be irritated.
In large quantities, borax can cause poisoning. Therefore, it is not recommended to drink, smoke or eat while working with borax. Personal protection is nothing unusual: it is overalls, safety glasses, work gloves, etc.
Borax should be stored indoors and always in packages - no spills. Typically, storage is carried out in special containers that should stand on a hard surface. The shelf life of borax is only six months, which must be taken into account when planning purchases and use.
TECHNOLOGY
Forge welding technology is simple, but at the same time very labor-intensive. It requires iron patience from the blacksmith, since it takes a lot of time and physical strength to complete one stage. But if you do everything right, you will end up with great results. Next, we will tell you all about forging welding technology.
HEAT
It all starts with preheating the parts. Heating is carried out in special furnaces or furnaces. It is important that the flame does not have oxidizing properties and there should be no excess fuel or lighter fluid in the fireplace. We recommend using charcoal as fuel. It has proven itself well because it does not contain sulfur. And excess sulfur leads to deterioration in the quality of the finished seam.
Coal is also used, but it may contain up to 1% sulfur. Make sure that the coal fractions are more or less the same size. The coal itself must be sifted and medium-sized.
First, coal is loaded into the furnace. It must burn well so that a small percentage of the sulfur evaporates. Then you need to heat the ends of the parts, which will then be joined. The average heating temperature is from 1300 to 1400 degrees Celsius. If the steel is low carbon, then when exposed to this temperature it will turn white. If the metal from which the part is made has a high carbon content, then the heating temperature should not exceed 1200 degrees. The metal should change color to white and yellow.
Such high temperatures are used only for heating; during forging, the temperature decreases. Therefore, keep in mind that there is a possibility of overheating of the metal and the formation of scale. To avoid this, you can use flux for forge welding. Flux is applied directly to the part, but not beforehand, but directly during heating. You can buy a special flux in the store, or you can use washed and sifted river sand.
There is no need to pour a thick layer of flux, otherwise the metal simply will not warm up and a lot of slag will form. Sprinkle a thin layer of flux. You can mix river sand with brown sand, then there will be fewer impurities during forging. But you should not use borax if you have high-quality purified coal. This will not bring the desired result. But if the coal is bad and contributes to the formation of slag, then borax can help. By the way, if you don’t have borax, you can use regular table salt.
There is one more trick regarding fluxes. If the part is small, then flux may not be used. Heat the workpiece and then quickly move it into the sand. The sand itself must first be poured into a metal box, which should be placed on the forge. The sand will warm up a little and the temperature difference will not be so large.
Also keep in mind that if you use sand, slag will still form. It will flow off the part along with the sand, so add sand as needed. Usually it requires pouring sand two or three times during the entire heating. It is not necessary to remove the part from the fire at this time.
You can also mix flux with iron filings if the metal contains a lot of carbon. Ferromanganese can also be used. Such mixtures help improve the quality of the seam because they absorb excess carbon.
Sometimes there are situations when you need to weld two parts from different steels. We recommend heating the part with the lowest carbon content first. And the second part should be heated after a short period of time.
FORGING
Now about forging. As soon as the part has warmed up well, it needs to be removed from the furnace or forge and placed on an anvil. Immediately you should make several blows on the anvil. This way you will knock down the slag. Next, you need to dock two heated workpieces and apply several light blows using a forging hammer.
The blows must be frequent and rhythmic, and the parts must be pressed tightly together to avoid oxidation of the metal. Then you need to increase the impact force while maintaining the same speed. Thanks to strong blows, the two workpieces are finally connected to each other and begin to take on a single shape. To increase the strength, you can forge not only the ends of the two parts, but also the areas adjacent to them. The forging itself must be done from the middle of the connection to the edges. This will ensure that the slag leaves the welding zone evenly.
Some craftsmen, after forging, reheat the finished parts. Then the forging is performed again. In appearance, such a product looks more monolithic, but the main thing here is not to overdo it. Otherwise, numerous heating may, on the contrary, deteriorate the quality of the seam. And you must remember that the forge welding joint itself is not that strong.
What is used as fluxes
Man learned to forge metal more than 2 thousand years ago, and the first thing that was sprinkled on metal during forging at the dawn of blacksmithing was sand. It is still used today. It should be fine river sand, dry, free of clay and other impurities.
Sand is the basis of the flux mixture. But to improve its quality, other components are added to the sand:
However, borax is more popular in blacksmithing, and it makes sense to talk about this component of flux mixtures in more detail.
GENERAL INFORMATION
Forge welding (also known as forging welding) is a method of joining metals, the essence of which is to form a weld using forging tools. The metal is brought to a plastic state and struck with a forging hammer. Before the invention of RDS, this welding method was used everywhere. But now forge welding is used only for joining parts made of low-carbon steel.
To get a high-quality seam, you need to thoroughly clean the metal. Contaminants and corrosion should not prevent the weld from forming during forging. But you need to understand that forge welding is labor-intensive and low-productivity work. In addition, the seam is not as strong as desired. For this reason, forging welding is not used in production, but remains the domain of private workshops. However, with the help of such simple technology, you can perform simple repairs in the field with your own hands.
Features of the soldering process
There are various soldering options. Many of them have a similar operating algorithm.
Submerged Soldering
For a quality connection, the following steps are necessary:
- The solder must be applied to a clean surface that acts as a base. It is necessary to remove any oils, paints, waxes and other impurities using a solvent, steel brush, or fine sandpaper.
- In order for the solder to connect to the tip of the soldering iron, heat it up for a few seconds, and only then apply the solder. Hold the soldering iron like a handle, near the base of the tool.
- Both parts of the workpiece that will be soldered must be hot to form a good bond.
- The tip of the soldering iron heats both sides of the workpieces.
- The solder will not flow well on the heated base metal. Enough solder should be used to form a strong connection.
- Remove the tip from the joint area as soon as the solder begins to flow.
- Do not move the solder joint while the solder is cooling. Do not overheat the connection as this may cause damage. Transistors and some other components may be damaged due to the heat of soldering. The alligator clip can be used as a heat sink to protect these components. By absorbing heat, the alligator clip reduces heat, helping prevent damage.
- Soldering a connection can only take a few seconds, and even an amateur can perform the operation. If the seam looks bad, reheat it and try again. Bad bonds (also called dry bonds) must be melted and remade. Wipe the tip of the soldering iron to clean it. Unplug the soldering iron when not in use.
What GOSTs regulate
Until 2009, forge welding was regulated by the document GOST 2601-84 “Welding of metals. Terms and definitions of basic concepts."
This version of the document defines forge welding as “furnace welding in which upsetting is accomplished by hammer blows.” GOST was put into effect on February 29, 1984. A reissue with changes was published in October 1996. The document has become invalid since 07/01/2010.
Active
Types of welding are now regulated:
- GOST R ISO 17659-2009 “Welding. Multilingual terms for welded joints.”
- GOST R ISO 857-1-2009 “Welding and related processes. Dictionary. Part 1. Metal welding processes. Terms and Definitions".
Both GOSTs came into force on 08/04/2009.
The first document defines the general section - pressure welding . This is “a welding carried out by the application of an external force and accompanied by plastic deformation of the mating surfaces, usually without filler metal.” The note specifies that “mating surfaces may be heated to facilitate the formation of the joint” (ISO 857-1).
But the second GOST gives a description of forge welding in paragraph 4.1.6.12 . It reads: “forge welding is pressure welding in which workpieces are heated in a furnace, and the seam is obtained as a result of blows with a hammer or the application of another pulse force sufficient to plastically deform the mating surfaces.”
Forging or forge welding with borax
Use of borax according to standards.
The forging process is characterized by strong heating of the workpieces - these are important technological nuances. As a result of such heating, a significant layer of scale is formed on the surfaces of the metal parts being welded until they burn out.
This is where borax comes into play as a savior: metal surfaces are covered with a layer of a mixture of sand and borax - an excellent flux is obtained.
To understand and appreciate the method using borax flux, you need to understand the process itself. Forge welding is a mixed physical method of influencing metals to join them.
Its essence is mechanical action in the form of blows from a forge hammer combined with heating to increase the ductility of the metal.
Forge welding is used for welding steel alloys with the lowest possible carbon content - at the level of 0.3%. High-carbon steels are not suitable for forging; their weldability is too low for this purpose using this method.
A mandatory requirement before the process is to thoroughly remove any contaminants and oxide films from the surfaces of the workpieces.
It should be noted that forge welding, in principle, does not produce strong metal joints; it is far from the most reliable method of forging. In addition, when using it, you cannot do without the professionalism of a blacksmith - without this nothing will work.
Therefore, it is practically not used for industrial purposes and in factories. But when it comes to repair work in the field and in unfavorable conditions, this method is used quite often.
