When processing non-ferrous metals, difficulties often arise, since at high temperatures their physical properties change. Particularly noteworthy is the welding of brass, in which the active evaporation of zinc occurs. Despite the difficulties, it is quite possible to work with this alloy in domestic conditions.
Basic material properties and preparation
Before brass welding is considered in detail, it is necessary to familiarize yourself with the characteristics of the material itself. The alloy contains two base metals - copper and zinc. The content of the latter may vary between 5-45 percent. It is introduced not only to improve physical properties, but also to reduce the cost of the final product.
A large number of products are made from brass. These include all kinds of bushings, adapters, pipes and various decorative elements. In their production, alloying elements can be added , affecting the quality characteristics:
- tin can increase corrosion resistance:
- aluminum to some extent reduces the volatility of zinc;
- silicon improves weldability with a slight loss of strength;
- lead makes it possible to obtain less hard products for convenient processing by cutting.
Zinc and copper billets, as well as some types of other metals, act as initial raw materials for the manufacture of the alloy. In some cases, domestic waste may be used. Melting is carried out in rooms with exhaust ventilation through induction furnaces.
Difficulties in creating one-piece connections
In order for brass welding at home to be performed efficiently and safely, you need to know about the problem points. Permanent joints obtained by local heating will be reliable only if special requirements are met. In the course of work, one must not forget about safety measures, since during thermal exposure hazardous fumes are emitted.
The main problem lies in the active burnout of zinc, which is associated with its low melting point (only 419 degrees). Most of the substance during the work disappears. In this case, some part interacts with oxygen, forming a white powder, which subsequently covers areas near the seam.
Work Precautions
Self-welding of brass should not lead to the formation of dangerous conditions for the human body. In connection with the increased activity of the allocation of volatile compounds, respirators should be used during work. Even with the use of special technological techniques, the burning of zinc ranges from 25 to 30 percent.
It is not allowed to carry out welding activities near materials and substances that ignite very quickly. In the immediate vicinity of the workplace, there should be no gasoline, wood shavings, tow or gas cylinders. A prerequisite is the presence of ventilation in the room.
Element Preparation Activities
When brass is welded to a small thickness, there is no need to preheat. When connecting massive elements, local heat treatment is recommended. Edge preparation may not be performed for products with a thickness of 1.5-6 mm.
If the elements have a larger cross section, then in any case, a V-shaped cutting of the seams is required. It is simple, but not optimal. It is best to carry out an X-shaped groove at which the opening angle is 30-45 degrees on each side.
Types and comparison of applied technologies
In many cases, brass is welded with argon. The technology of connecting parts in an inert environment is considered the most promising, as it allows to achieve a high speed of work. Other advantages of this option include:
- the possibility of obtaining seams with a clear geometry and purity;
- uniformity of structure in places of permanent connections;
- reliability of joints;
- profitability due to the use of inexpensive tungsten electrodes.
Another technology is gas welding. It does not involve the use of a source of electrical energy, which in some cases is very justified. With its application, it is possible to regulate the power of the outgoing flame in a fairly wide range. With the correct selection of filler materials, high-quality seams are formed.
Argon Brass Welding: Process Description
The environment from the protective gases provides an opportunity to mitigate the negative effects. Welding of bronze and brass with this option takes place using direct current having direct polarity. Due to the high probability of burn-through, it is recommended to process the docking place by means of a long arc.
The electrode is inserted into the burner, which is a conductive mechanism. After that, the unit is turned on. The operation itself is accompanied by increased crackling, which appears due to the release of zinc vapor. The filler wire is inserted into the seam manually.
Parts are combined by separate rollers, and not by continuous cooking technology. When closing the crater, it is desirable to slightly reduce the arc voltage. At the final stage, it needs to be removed to the side. Operating voltage should not decrease immediately, but gradually.
Use of gas equipment
In areas with no electrical source, arc technology cannot be applied. However, in this case, gas welding of brass is perfectly acceptable. When it is used, durable compounds are obtained, however, quite dangerous substances are required for work, which together with oxygen form explosive mixtures.
During work, the excessive evaporation of zinc can be avoided by using an oxidizing flame in a working burner. Oxygen should be much more than hydrogen. When processing the joint, an oxide film appears on the surface, which allows to some extent protect the surrounding space from zinc emissions.
When welding, filler wire is recommended to be placed at an angle of 15 to 30 degrees to the side edges. Transverse vibrations should be avoided during the operation. The burner should be at an angle of 70 to 80 degrees to the workpiece.
The filler material is placed above the molten bath directly into the flame of the burner. Do not immerse the used bar in the inside of the seam. When driving, it is advisable to adhere to a certain speed. Usually it is 15-25 cm per minute.
If billets of large thickness are connected, then they should be positioned at an angle of 10 to 15 degrees to the horizontal. Welding is carried out on the rise. As a rule, ceiling joints in this case are not performed, since the material is fluid.
Welding with other metals and alloys
Sometimes it is required to combine brass with other dissimilar materials. In this case, you need to know about the features of such work. When combined with steel, some difficulties may arise, which is associated with various physicochemical characteristics of the two alloys.
A common defect in welding is the appearance of cracks on the steel surface immediately below the brass layer. To reduce the risk of such defects, it is recommended to use a nickel alloy. Argon arc technology performed using tungsten electrodes is best suited.
The combination of titanium with copper alloys can lead to the formation of brittle chemical bonds. The best effect is achieved when using intermediate inserts. They are made of a titanium alloy alloyed with niobium or molybdenum. In some cases, the use of combined alloys is allowed.
The physical properties of niobium are in many respects similar to titanium; therefore, it satisfactorily welds with brass. However, the operation must be carried out in an inert environment. Often, special cameras are used, in which the atmosphere is completely controlled.
The final part
It should be noted that brass welding technology has its own characteristics, which should be taken into account when creating one-piece joints at home without the involvement of specialists. When studying all the subtleties of the process, it is quite possible to achieve a high-quality connection of the workpieces. As for the choice of methodology, it is more dependent on the availability of specific equipment and the conditions of work.