Research in Action:
|Cast Materials - 2007|
|Worldwide Report: Aluminum Cast Alloys: Enabling Tools for Improved Performance|
- The simplified continuous rheocasting process (CRP) reactor design has been adopted by and is being marketed by Buhler and the LTC (low temperature casting) process. Sound SSM castings have been produced using a variety of commercial alloys. Heat treatment studies are continuing in an attempt to optimize the cycle for –T5 and –T6 conditions. Both conventional and fluidized bed furnaces are being utilized. Productivity improvement opportunity!
Figure 1 – Photograph of the CRP reactor and a resultant SSM microstructure.
- The suitability of a newly developed high fluidity zinc alloy for industrial production has been shown. Lack of fill issues have been resolved and parts with section thicknesses as low as 0.012 inch have been successfully cast. The alloy not only improves die fill but also reduces gas entrapment compared to Alloys 3 & 5. Mechanical properties and casting characteristics have shown to be acceptable. Productivity improvement opportunity!
Figure 2 – This casting had fill issues which were resolved by utilizing the new high fluidity zinc alloy.
- An expanded database of properties has been developed for standard alloys such as Alloys 2, 3, 5, and ZA8, including tensile properties over an extended temperature range, compression at elevated temperatures, impact, rotating fatigue and creep. Only a minor amount of creep testing remains to complete this project.
- Wedge shaped and plate shaped semi-solid metal castings (thixocast) have been produced from SHS aluminum/TiC metal matrix composite material with up to 47% particulate. Wear resistance, hardness, and compression strength measurements show great improvement over standard aluminum and aluminum composite castings and comparable to cast iron.
Figure 3 – Processing route for thixocasting of SHS aluminum wedges for mechanical property testing.
- Three aluminum alloy compositions of thirty-eight formulations have been selected based on property improvement levels noted on laboratory cast specimens. Castings of a production configuration were produced at a member die caster and property measurements show an improvement in quality index.
- Zinc castings have been processed with new coatings and plating and are being prepared for corrosion testing to assess the protective nature of the coatings and platings.
- A magnesium automotive chassis component for test and evaluation has been successfully squeeze cast at two NADCA member die casters. Property enhancements are the current focus.
- A magnesium automotive front end component for test and evaluation has been high vacuum cast at one NADCA member die caster. Although soundness was adequate, focus for this component is also is currently on determining if properties can be enhanced.
- Castings of a production configuration have been produced from three alloy chemistries. Mechanical property testing is in process. A tool was produced for producing as-cast impact and fatigue bars. These properties are being compared to those of separately cast specimens of the same three alloys. A property database is being established.