Forging welding is perhaps the oldest way to bond metal. Blacksmithing was the only method of steel processing for several millennia, until in the XIX century, experts mastered the foundry. And in the XX century, technological progress was developed, as a result of which other progressive methods of metal bonding became available to humanity. Because of this, forging has lost its relevance. Today, this craft exists only formally, at the request of some artisans.
Basic principles
Forging is called a manufacturing process in which inextricable joints of metal components are created using high temperature and impact pressing. In other words, metal fragments are heated in a special furnace to a fluid state and, using percussion instruments on a metal base, they are joined. The whole process consists of the following steps:
- preliminary preparation of the joined surfaces;
- thermal heating to a predetermined temperature;
- connection with percussion instruments;
- final forging to establish the desired shape.
The most important condition in this case is the heating of the metal using high temperatures. Bringing the metal to the required temperature is controlled by changing the color of the hot surface. Thus, reaching a temperature of 1300 degrees, the iron becomes a bright yellow color. With an increase in heating to 1400 degrees, it begins to become bright white. Upon reaching the required temperature state, the connection should be made immediately. Otherwise, the quality of the product may suffer due to burnout of the material, which is accompanied by the formation of an excessive layer of scale.
Features
The flexibility of the compounds, due to thermal diffusion, using high pressure, when bringing the material to a soft plastic state, as a rule, for different types of metals and components has significant differences. Thus, low carbon steels with a carbon percentage not exceeding 0.6% are considered to be compliant with the compounds. In the case of an increase in percentage, the overall ability to combine is weakened.
Alloy steels and non-ferrous metals, including their alloys, are difficult to forge. In addition, all varieties of cast iron is absolutely impossible to connect in this way. The main obstacle to the bonding process in the process of thermal diffusion is the formation of a layer of scale on a heated surface. This interlayer is formed by refractory oxides under the names FeO and Fe 3 O 4 , which have a weak ability to melt under the influence of temperature, which is sufficient to weaken the main metal surface.
To reduce the effect of interfering oxides, the surface to be subjected to the procedure is coated with special fluxes for forging. They are acidic in nature. Most often, table salt or boric acid is used for this purpose. A calcined drill for blacksmithing may also be suitable. In other cases, the use of flux is replaced by some improvised materials. Such, for example, can be a glass battle, as well as fine sand from the river bank, which can replace blacksmith welding with brown.
This welding is considered one of the complex processes in technological terms, as it requires a lot of knowledge and practical skills from a specialist. For example, it should be understood that the ability to connect metal appears only when a certain temperature is reached. In case of insufficient heating of the surface, a defect will be obtained, called a lack of fusion. And if the metal is overheated, a burn is formed, which also will not lead the product to a high-quality shape.
Ways
There are a number of simple joining methods that do not require lengthy preparatory steps for blacksmithing. The following technique names are used:
Conditions
To perform actions using these techniques, you must adhere to only one mandatory rule - the ends of the workpieces must have a convex shape, and also have thickenings at their ends. This condition must be observed because in the process of forging by forging during heating of the workpiece on the metal surface, a slag film is formed. And if the surface has bulges, then the particles of slag can be squeezed out. The bulges formed at the ends of the blanks intended for forging serve as a technological reserve in the process of acquiring the desired shape.
Other technologies
There are also more sophisticated blacksmith welding technologies that allow you to create products that play the role of components in complex mechanisms or represent decorative elements in various design compositions:
- One such method is proven splice welding. This technique was used before, connecting steel strips, in the process of manufacturing metal tires needed by village carts.
- The next method is welding using drafts. This technique is effective in connecting the overall components.
For welding in the split, the processed edges of the strips undergo special training. They are first pulled and then chopped so that before welding there is the possibility of joining by overlapping. Only after this, the fragment is heated to the desired temperature and is welded using forging. The second method of forging steel welding involves the use of an additional element. These elements are called checkers.
Application area
Forging welding today is no longer the main way of joining metals. It is used mainly for the manufacture of complex metal components in intricate patterns of forging masters. Artistic welding of metal fragments allows you to create the most incredible forms that adorn various facades.
In addition, this welding method sometimes finds application for the manufacture of some hand tools needed in everyday life. And it lost its industrial value due to low productivity against the background of other connection methods.
Minuses
The disadvantages of this technology include:
- low heating rate;
- insufficient strength of the obtained compounds;
- significant heterogeneity of the process of precipitation;
- high qualification requirements from performers.
Only a few industrial divisions continue to use forge welding. Currently, using this technology, they continue to produce metal water pipes whose diameter does not exceed 100 mm. Creating the conditions for this procedure, strip steel is heated in special furnaces, and then rolled linearly through the coils. Then drag it through the mandrel at high speed. In this way, the joint of the seam of the water pipe under the influence of high pressure occurs.
Also on an industrial scale, forging welding is still used in the manufacture of complex bimetallic plates. Usually for this they use joint rolling of hot billets through special rollers or apply the pressing method using thermal furnaces, having vacuum conditions. Forging welding allows you to give a multilayer structure to products, which in some cases is of great importance.
Equipment and materials
To set up a small forge for the handicraft production of some products or the manufacture of art forging elements, not so much is needed.
If you have certain equipment and a few tools, you can easily establish your own production of metal forging welding:
- First of all, you need one stationary horn and one portable. This is a special tool necessary for heating the surfaces to be welded. A portable gasoline automobile may well become a portable mountain.
- Next, a group of anvils is required. It is important that it be sure to be both large and small. Moreover, having only a two-horned anvil is not enough. One-horned must also be present.
- A set of blacksmith mites made up of as many sizes as possible.
- A set of forging hammers, which will allow for the main forging process.
- Two tanks designed for cooling materials. One of them must be filled with water, and the other with oil.
Important
It is imperative to provide the forge with all necessary safety equipment. In addition, personal protective equipment should be included in the package - glass glasses, a protective leather apron, thick canvas gloves.