Community Research and Development Information Service - CORDIS

CONVECT-SOL, a software package for convective effects in solidification

A software package, named CONVECT-SOL, has been developed for the treatment of convective effects in solidification processing of materials. The 2 following configurations are considered:
shaped castings in a foundry, more particularly problems of cold shuts, poor grain structure or detrimental distribution of inclusions or reinforcing particles;
massive crystals, grown by Bridgman or floating zone techniques, with special attention to banding or striation phenomena.

The package includes a lot of data resulting from collective experimental and theoretical work. CONVECT-SOL has the following attributes:

Improved description of solidification coupled to flow:
This is important in the present trend to thinner and lighter pieces. A special module detects conditions in which solidification stops the flow before the print is filled, leading to the defect named cold shot or cold shut. This involves microstructure formation mechanisms.

Description of the behaviour of particles in relation to solidification:
These particles can be inclusion particles in a piece of superalloy, or particles of inoculating ferro alloy in cast iron, or reinforcement particles in a cast metal matrix composite. A module is proposed for simulating the interactions of such particles with the solidifications front.

Improved description of buoyancy flow:
Commercial codes are mainly oriented to forced flow. In fact, buoyancy driven flow has important consequences on the growth of large crystals, in particular banding and striations. In shaped castings, buoyancy flow can strongly affect solidification in massive parts, creating segregation marks (ghost lines). An improved formulation will result in a more precise design of the feeder system, thus leading to savings in material, time between design and production, and finally cost.

Surface tension driven flow (Marangoni flow):
Implementation of thermocapillary flow concerns the zones of liquid free surface which are submitted to a high temperature gradient. An industrial case is floating zone crystal growth. Besides, it is known that thermocapillary flow strongly affects liquid pool and solidification in welding conditions.

Improvement resulting from solidification in centrifuge machines:
In this case the flow results from an increased gravity coupled to Coriolis effect. Solidification experiments in centrifuge machines have demonstrated a better stability for growth of single crystals. Moreover this part can give new possibilities for flow in centrifugal shaped castings, for industrial manufacture of tubes, automotive wheels, jewellery, dental prosthesis parts, etc.

Contact

Francis DURAND
Tel.: +33-76825213
Fax: +33-76825249
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