According to the physico-mechanical characteristics, titanium acts as the most important modern structural material. It is quite widely used in industry and everyday life, therefore, in some cases it is soldered. Its weight is almost 2 times less if compared with carbon steels and a number of non-ferrous alloys. Its density is equivalent to 4.5 g / cm3. Titanium is very durable (the minimum σb value is 300 MPa), ductile (δ is equivalent to the limit from 25 to 50%) metal; The indicator of its corrosion resistance in some aggressive media exceeds this characteristic, characteristic of corrosion-resistant steels.
Argon arc welding of titanium.
Features of soldering titanium
On the surface of titanium there is an alpha plaque, which suggests the presence of atmospheric gases. Before the soldering process, the above layer should be removed using sandblasting, which can be replaced by etching in a mixture with a specific composition: 20-30 ml H2NO3, 30-40 ml HCl and 1 liter of water. The period of etching should be limited to 5-10 minutes. whereas the temperature indicator should be equal to 20 ° C. After such a treatment, an oxide deposit of an insignificant thickness will still be present on the surface of the material; it will prevent the base from being wetted by solder. For this reason, at home, masters are trying to solder the material using special fluxes, the composition of which is similar to the one that have fluxes designed for working with aluminum. However, it is worth being prepared for the fact that the conjugations obtained by means of such fluxes do not have considerable strength and quality.
The scheme of laser soldering propping plates.
As a rule, titanium and its alloys undergo soldering under vacuum or argon conditions, the latter must be freed from particles of oxygen, water vapor and nitrogen. Exceptionally, under ideal conditions, oxide and nitride deposits on the surface of the material are neutralized in the metal, which is true if the temperature regime during work exceeds 700 ° C. This causes work with titanium at a temperature range from 800 to 900 ° C, which guarantees quick cleaning of the material base and intensive wetting with solders.
Soldering of titanium alloys at significant temperatures is carried out not so often, which is especially true for furnace smelting. This is explained by the fact that during prolonged heating, when the temperature exceeds 900 ° C, there is a tendency to increase the grain and deteriorate the plastic characteristics. Since the level of strength of the main metal is almost unchanged, in some cases, the pairing of titanium alloys by the method of soldering is carried out at a mark of 1000 ° C.
Hydrogen present in titanium and lowering its plasticity is eliminated during the soldering process or during heating at 900 ° C. Therefore, work with titanium should be carried out in a space devoid of air, this is preferable to work in a neutral atmosphere.
Titan, although it involves the provision of difficult conditions, but still amenable to smelting, while cast iron refers to difficult-to-weld metals.
Increasing the temperature during welding and subsequent cooling contribute to changes in the structure of the characteristics of cast iron in the areas of melting and weld, which indicates that it is very difficult to obtain joints devoid of defects with the required level of properties.
- the need to use special fluxes;
- the need for a vacuum;
- It is recommended to use silver as a solder base.
Installation of wave soldering.
Before you solder titanium at home, you need to choose the right solder, method and features of the work. It should be noted that titanium contributes to the formation of brittle intermetallic compounds in the solder joint with almost all the elements that are in the solder. For this reason, as a base for solder, silver is usually preferred, which forms not so brittle intermetallic compounds with titanium as compared to other metals.
It is very problematic to make high-quality soldering of cast iron independently, as regards the soldering of titanium in vacuum by means of aluminum without additives. This is explained by the fact that intermetallic phases arise in the seam, and the conjugation does not have any strength.
The thickness of the interlayer can be minimized by using Ni-doped aluminum as the solder. This and some other elements of 1% each affect the displacement of the intermetallic layer.
Soldering of alloys of the described metal by means of tin-lead or other low-temperature solders is used infrequently. In this case, before starting work, titanium needs to be coated with nickel using a chemical or electroplating method. But if it is necessary to use cast iron in the process of soldering, then it is preferable to entrust the matter to professionals.