John Courtenay will be presenting a joint paper: 

“Results in production of an improved grain refinement practice for 6XXX extrusion alloys” by John Courtenay, Rein Vainik  and Marcel Rosefort  

Authors: MQP Limited and Trimet Aluminium SE, 

Abstract: This paper describes a project undertaken at Trimet Aluminium SE to improve grain refinement of extrusion alloys. The work involved three stages.

The first stage comprised making small scale tests using the Opticast method on 4kg melts at the MQP laboratory in Stockholm.In the second stage testing was carried out on the R&D casting pit at Trimet where a single billet was cast from a 1.2t furnace.The third stage involved making full casts of 6060 billets on a production casting pit and evaluating these in terms of grain size, metallography and subsequent performance in extrusion.

Overall it was concluded, based on the results obtained from stages one and two, that it was possible to achieve the target grain size of ASTM Grade 2.5 for alloy 6060 in production using an application rate of 0.16 kg/t of Optifine. This means a reduction of 68% from the current addition rate of 0.5 kg/t of standard grain refiner bringing significant benefits in terms of both overall economy and quality.

The results of the third stage of the project confirmed that analysis and showed that an addition rate of 0.16kg/t can be used in regular production. This provides a comfortable safety margin in terms of avoiding cracking problems and a represents a substantial reduction in grain refiner addition of 68% compared with the standard grain refiner previously used.


Grain size measurement in billet refined with 0.16 kg/t Optifine

Billet sampled 2cm from shell zone, ASTM: 2.15, Grain Size: 170.6µm