Influence of gas impurities on weld metal properties

Medical titanium material It has high chemical activity and high affinity with oxygen and nitrogen in the air. At a lower temperature, titanium interacts with oxygen to form a dense oxide film. With the increase of temperature, the thickness of the oxide film increases. When the temperature exceeds 600 ℃, titanium begins to absorb oxygen and dissolve oxygen into titanium. At higher temperature, the activity of titanium will increase sharply and react violently with oxygen to form titanium oxide. Titanium begins to absorb hydrogen above 300 ℃ and nitrogen above 700 ℃. The result of oxygen and nitrogen pollution on titanium is that the strength and hardness of titanium increase while the plasticity decreases. Nitrogen has more influence than oxygen. Hydrogen content in titanium from 0.01% to 0.05% will sharply reduce the impact toughness of weld metal, while the plasticity will decrease less. This is the brittleness caused by hydride, which is often called "hydrogen brittleness". Hydrogen is also the root cause of weld porosity.

During fusion welding, the molten pool is like a small metallurgical furnace, and the molten metal is exposed to the atmosphere. If no corresponding protective measures are taken to isolate the molten titanium metal from the air, oxygen, nitrogen, hydrogen and other gas elements will be melted into titanium, forming brittle oxides or nitrides, which will sharply reduce the plasticity of weld metal and increase the tensile strength. In serious cases, brittle fracture will occur, and the plasticity is equal to zero.

In the textile industry, synthetic fiber and other industries are used as spinnerets, continuous bleaching machines, distillation towers, reaction tanks, condensers, heat exchange tubes, centrifuges, spinnerets, valves and pumps.

Titanium has been used as a corrosion resistant metal for 30 years in China, and has achieved great results. The state attaches great importance to the application and promotion of titanium materials. It can be predicted through recent research and application results, Titanium and titanium alloy bars In the future, machining will have a broader development prospect and application value in the field of corrosion prevention.

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