The alloy made of titanium and iron, aluminum, vanadium, molybdenum and other metal elements has excellent physical and mechanical properties such as high strength, high heat resistance and good corrosion resistance, and is widely used in chemical industry, marine engineering, transportation, medical treatment, construction As well as high-tech fields such as aerospace and military industry, it is an extremely important lightweight structural material, among which aerospace is an important downstream application field.
Titanium and titanium alloys are active metals and are widely used in aerospace, petrochemical and atomic energy industries. The main problems in brazing of titanium and titanium alloys are as follows:
① The oxide film on the surface is stable, titanium and its alloys have a high affinity with oxygen, and a very stable oxide film is easily formed on the surface, thereby resisting the wetting and spreading of the solder, so it must be removed during brazing.
②It has a strong gas absorption tendency. Titanium and its alloys have a tendency to absorb hydrogen, oxygen and nitrogen during the heating process, and the higher the temperature, the more serious the absorption, so that the plasticity and toughness of titanium metal decrease sharply, so brazing should be Carry out in vacuum or inert atmosphere.
③ It is easy to form intermetallic compounds. Titanium and its alloys can chemically react with most needle materials to form brittle compounds, causing the joints to become brittle. Therefore, brazing filler metals used for brazing other materials are basically not suitable for brazing active metals.
④The organization and performance are easy to change. Titanium and its alloys will undergo phase transformation and grain coarsening when heated, and the higher the temperature, the more serious the coarsening, so the temperature of high-temperature brazing should not be too high.