SBIR-STTR Award

Metal forming operations are among the most costly materials processing steps that require large capital investments and are extremely energy intensive. A technique called semi-solid forming is an attractive process but the cost of preparation of semi solid alloys is relatively high, due to the expense associated with electromagnetic or mechanical stirring of the liquid alloy during solidification. The principle objective of this project is to develop a new, less expensive, energy efficient process for producing alloys (such as semi-solid aluminum alloys for automotive applications), which can be heated to a semi-solid state, transformed and effectively formed into parts which meet or exceed the existing structural and mechanical strength characteristics of semi-solid forming. Phase I of the project will concentrate on traditional aluminum silicon alloys 356 and 357 which are currently being produced for semi-solid forming by electromagnetic stirring. Formability studies will be performed to determine if combinations of configuration, injection temperature and pressure will allow ease of formation and acceptable final properties. These results will be compared to companion experiments using electromagnetically stirred ingot.

Commercial Applications and Other Benefits as described by the awardee:
The principle benefit of a successful research effort would be reduced cost semi-solid formable aluminum alloys. These are produced exclusively by semi-solid thermal treatment, which permit economical replacement of heavier cast iron and steel parts, particularly in automotive applications, resulting in reduced energy consumption both in raw material formation and vehicle fuel consumption.

The relatively high cost of producing formed parts from semi-solid metal (SSM) aluminum alloys is due largely to the high cost of the ingot. Currently, semi-solid forming requires electromagnetic (EM) or mechanical stirring of the ingot during solidification to produce a spherical micro-structure. This project will develop a novel method to produce a similar structure by controlled heating to transform a dendritic structure to spherical structure at ingot temperatures in the semi-solid regime. This skips the expensive electromagnetic stirring step. In Phase I, ingots of alloy 356 and 357 with a dendritic structure were heated by induction to form a spherical structure and then formed into various parts. The properties of these parts were comparable or superior to those produced from EM ingots. Phase II will produce SSM parts using SSTT (semi-solid thermal transformation) on a production basis employing diagnostics for process control. New alloys designed especially for SSM/SSTT will be developed.

Commercial Applications and Other Benefits as described by the awardee:
The technology should lead to near-net shaped parts for automotive applications with improved properties and lower costs compared to conventional casting.