The pores are Medical titanium material Common process defects in welding. The mechanism of pore formation is that the gas mixed with liquid metal in the welding process forms bubbles through diffusion, dissolution, nucleation, growth and other processes. As the solidification and crystallization speed of the molten pool is very fast, the grown bubbles will remain in the solid metal in the form of pores when it is too late to escape from the liquid metal. Gases such as hydrogen and carbon monoxide that form pores are mainly generated by the thermal action of organic pollutant crystal arc. Sometimes the weldments and welding materials are fully cleaned, cleaned and varnish protected before welding, but there are still pores in the cold wind. This indicates that the important pollution source has not been removed. Practice has proved that an important air source is often neglected, that is, the moisture in the air. A comparative experiment proves this point. Welding in two environments with different air humidity: one is in rainy weather, with relative humidity above 90%; the other is in sunny weather, with humidity less than 40%. Other pre welding cleaning, cleaning and welding operations are identical. When the air humidity is high in rainy days, there are many and large pores in titanium welds, while when the air humidity is low, there are no pores in the welds. This fully shows that the generation of pores is closely related to the air humidity.

In order to reduce this adverse effect, titanium welding should try to use a softer welding specification, that is, smaller welding line energy and faster cooling speed. Titanium has high chemical activity and high affinity with oxygen and nitrogen in the air.

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