At normal temperature, titanium reacts with oxygen to form a dense oxide film, which gives it high chemical stability and corrosion resistance. In the welding process, the welding temperature is as high as 5000 ~ 10000℃, and titanium and its alloys react quickly with oxygen, hydrogen and nitrogen. According to the test, titanium alloy in the welding process, the temperature above 300℃ can quickly absorb hydrogen, above 450℃ can quickly absorb oxygen, above 600℃ can quickly absorb nitrogen. When these harmful gases are invaded in the molten pool, the plasticity and toughness of the welded joint will change significantly, especially above 882 ℃, the joint grain is severely coarse-enlarged, and the martensitic structure is formed during cooling, so that the strength, hardness, plasticity and toughness of the joint are reduced, the overheating tendency is serious, and the joint is seriously embrittle.
Therefore, when welding titanium alloys, comprehensive and reliable gas protection should be carried out for the molten pool, the molten drop and the high temperature zone, whether on the front or the back. This is the key to ensure the welding quality of titanium and its alloys. In a period of time after welding, the near seam zone of titanium and its alloys is prone to crack, which is caused by the diffusion of hydrogen from the high temperature molten pool to the low temperature heat affected zone. With the increase of hydrogen content, the precipitated titanium hydrogen compound increases, the brittleness of the heat affected zone increases, and the structural stress caused by the volume expansion of the precipitated hydride leads to the generation of cracks. If you want to know more please clickhttps://www.lionsemachining.com/contact.html
