titanium axle casting and casting surface quality analysis

3 smelting , casting and casting surface quality analysis
3.1 Melting and casting
Because of the high melting point of titanium alloy , chemical activity , smelting and casting must be performed under vacuum or inert gas . The experiment used a water-cooled copper material titanium crucible vacuum induction melting and casting furnace , the main process parameters are shown in Table 3 . Using Ti-6Al-4V alloy , the cast as an aerospace components, size of 150mm × 100mm, thickness 2.5mm, shell preheat temperature 300 ℃, gravity casting , casting the shell intact, no cracks , clean up after the castings shown in Figure 3 .

Table 3 Parameters melting titanium major

Table3 Main melting parameters of Ti alloy

Before pouring the vacuum degree / mbar 1.6 × 10-2

Before pouring water temperature / ℃ 37

When pouring the titanium wire price current intensity / A 870

When pouring voltage / V 565

When pouring electric power / kW 496

Frequency / kHz 7.91

Figure 3 titanium castings

Fig 3. A casting of titanium alloy

3.2 casting surface quality analysis

Birds casting surface silvery white , casting a clear outline , no surface flow marks and cold shut . Surface roughness Ra6.3μm.

Casting the X ray diffraction analysis that the casting surface Ti, ZrO2 and Ti2O, causes Ti2O ZrO2 is at a high temperature Ti reaction occurs with the reaction equation is as follows :

ZrO2 + Ti = Zr + TiOx + Oy

Zr and O to the diffusion of titanium castings , constitute the reaction layer .

EPMA sectional view of the casting for the detection , measurement and distribution line section of the zirconium -plane distribution , the results shown in Figure 4 . The reaction of zirconium castings depth of 25 ~ 50μm.
Figure 4 Distribution of zirconium wire probe and the surface distribution of photographs (a) casting microstructure ; (b) line distribution ; (c) surface distribution
Fig.4 Distribution of Zr titanium rod stock (a) Microstructure; (b) Linear; (c) Planar
4 Conclusion
( 1) The main component of sand and zirconium dioxide powder as refractory organic zirconium sol as a binder , a kind of cost-effective suitable for titanium casting Casting Shell Technology .
( 2 ) a systematic study of the effects of powder -liquid ratio , calcination temperature, time, etc. microwave dewaxing process parameters on the coating properties and performance of the shell to determine the optimum process parameters.
( 3 ) the use of water-cooled copper crucible vacuum induction furnace casting out a complete and clear Spade aerospace castings dimensions of 150mm × 100mm, thickness of 2.5mm. Casting titanium sheet suppliers surface roughness Ra = 6.3μm, the thickness of the reaction layer is 25 ~ 50μm.