The Gr5 cast titanium rod ingot is used as the original blank for the production of the deformation titanium alloy, which can be processed into all kinds of semi-finished products and finished products. Another important application is as the master alloy production of casting titanium alloy. At present,there is a rapid development of casting titanium rod in aviation, shipbuilding and oil chemical industry. Compared with Gr5 forging titanium rod, casting has the advantages are as follows: forming directly, shorten the production cycle, simplifing the process chain, increasing yield and cost decreased significantly.
The melting and casting of Gr5 titanium rods should be carried out in a vacuum self consuming condensing shell furnace, Firstly,the titanium liquid itself condensate a thin shell on the wall of the water cooled copper crucible to separate the titanium liquid from the copper crucible, so as to prevent the crucible material from polluting the alloy. Besides,The mould for Gr5 casting titanium rod should be made of special materials, because the common used refractories , such as magnesia (MgO), corundum sand (Al2O3), zirconium sand (Zr2O3) and quartz sand (Si02), will have a violent reaction with titanium at 1800 C. At present, the cast type of Gr5 titanium rod is mainly graphite type, including machined type, molten mould type, tamping graphite type and pyrolytic graphite type. In addition, the calcium oxide type, metal type and refractory ceramic type are also available.
Now, most of the cast titanium alloys have the same composition with deformed titanium alloy, such as Gr6 and Gr5. But the crystallization interval is smaller (40℃ -- 80 ℃), the linear shrinkage rate is smaller (0.5-1.5%), and higher hot cracking resistance. In a word, cast iron has good technological properties. During the production, In order to overcome the shortcoming of poor feeding capacity caused by low overheating and little proportion, the centrifugal casting is often used.
Another advantage of casting Gr5 titanium rods is that its mechanical properties are very close to the deformation of titanium alloys, and it also exceeds the conventional Gr5 forging titanium rod. in terms of heat resistance and fracture toughness, so casting has a more broad prospect.