Titanium tube weld cracks and pores problems titanium alloy pump

Titanium tube weld crack problem

When the possibility of titanium sunrui titanium alloy pump welding, thermal cracking of welded joints is small, it is because few impurities

in titanium and titanium alloys S, P, C , etc. , low melting point of S, P eutectic formed at the grain boundaries

rarely generation, coupled with effective crystallization temperature range narrow, titanium and titanium alloy

solidification when a small amount of shrinkage , weld metal does not produce heat cracks.
When titanium and titanium alloy welding, weld when an oxygen , nitrogen is high , the performance of the weld heat

affected zone or become brittle in the larger weld stress, cold cracking occurs . Characterized by cracks in the

weld called a few hours or even longer delay cracks. The study showed that the hydrogen diffusion welding process is

the main cause of such cracks. Hydrogen in the welding process to a lower temperature by diffusion of the high

temperature heat affected zone deep pool , the area increase the hydrogen content of the precipitates increased so

that the amount of TiH2 , brittle heat affected zone is increased , the other due to volume expansion caused by

precipitation of hydrides greater the stress , plus a hydrogen atom diffusion and aggregation to the high stress

areas of the area, resulting in the formation of cracks . This delay prevents cracks approach is to reduce the

welded joint main source of hydrogen .

Titanium tube weld porosity problems

When titanium pipe welding , porosity is Sunrui titanium coils often encountered a major problem. The root cause of the formation of pores

is affected as a result of hydrogen .
Prevent blowholes process measures are:
1 ) in high purity argon welding , argon gas purity not less than 99.99%
2 ) the elimination of titanium tubes , oil and other oxide on the surface of titanium and titanium tubes eye

organics . Can be cleaned with a chemical and mechanical methods.
3 ) subjected to the bath gas well , control the flow and the flow rate of argon gas , to prevent turbulence ,

impact protection.
4 ) Choose the appropriate welding process parameters, welding specification , increasing the residence time of deep

pools to facilitate the use Sunrui aerospace investment casting of air bubbles escape , which can effectively reduce porosity.