TITANIUM CASTINGS
Titanium Casting Technology is an attractive near net-shape technology which minimises costly material wastage. This has become a viable method of achieving low-cost high-quality titanium components for demanding applications.
Generally, cast products of steels and aluminium alloys have properties inferior to those of wrought products. But this is not true with Titanium cast parts; they are generally comparable to wrought products in all respects and quite-often superior. Consequently Titanium castings can substitute forged and other machined mechanical parts in case of many demanding applications.
Phase transformation of b to (a+b) occurs at temperatures well below the solidification temperature of the alloys. The cast dendritic b structure is wiped out during this solid state transformation, leading to an (a+b) structure, further the microstructure can be improved by means of post cast cooling rate changes and subsequent heat treatment. This explains the superior behaviour of titanium castings.
The casting of Titanium and Titanium Alloys presents special problems due to their high reactivity at pouring temperature. Vacuum melting, special mould-making practices and equipment are necessary to prevent material contamination.
INVESTMENT CASTINGS
In this method, titanium is cast in a ceramic shell under vacuum conditions either by using a centrifugal table to assist the liquid metal flow or by simply by pouring liquid metal in a static mould (gravity pouring). The shell is made from a wax pattern assembly dipped in ceramic slurry, stuccoed and dried till a ceramic shell of desired thickness is achieved and the same is hardened by firing after melting and draining the wax pattern. Investment Casting provides very good surface finish and close dimensional control and is suitable for production of high-quality components. In practice, the minimum wall thickness which can be cast through investment casting route is about 2 mm.
SAND MOULDING PROCESS :
Titanium sand casting technique is based on conventional foundry mould making practice. Gravity pouring is carried out under vacuum conditions after removal of moisture from the mould by appropriate firing. Titanium Castings are being made using Vacuum-Arc Skull melting facilities wherein Titanium is melted and liquid metal is poured into the mould. Both melting and pouring are carried out under vacuum
SPECIALITY OF MIDHANI
(a) Separate fully controlled shell heating furnace for making very thin walled castings (b) Facilities and expertise in all types of heat treatment viz., softening, annealing, solution annealing, normalizing, hardening and tempering (c) Facilities and expertise in non-destructive testing (d) Spectrometer for online testing (e) Vacuum Induction Melting of master melts to provide consistent input material for investment casting.
SIZE OF CASTINGS : Length Upto 450mm; Dia. Upto 400mm; Weight Upto 50 Kgs
Midhani offers castings of titanium conforming to ASTM-B 367 specifications.
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