Advancing Casting Capabilities
Top-rated presentations at the 115th Metalcasting Congress and Cast in North America show tackled important issues and delivered intriguing results.
properties of wrought alloys? These were among the questions
W Demystifying
Magnesium Casting Wouldn’t it be nice to know, once
and for all, which emerging method of casting magnesium alloy AZ91 is and will be the best, and which will be doomed to 8-track-like obscurity? Liang Wang, Ratessiea Lett, Sergio
Felicelli and John Berry of Mississippi State Univ., Mississippi State, Miss., set out to examine four different processes: indirect squeeze, low pressure perma- nent mold (LPPM), T-Mag (a permanent mold casting process involving filling from the bottom) and ablation (a sand casting process in which the mold is blasted away with water during solidifi- cation). Magnesium automotive control
Visible here are casting defects on the fracture surfaces of four-point bending test speci- mens taken from control arms produced by (clockwise from top left) indirect squeeze casting, low pressure permanent mold casting, ablation and T-Mag casting.
arms were cast in all four processes at several different metalcasting facilities, and the parts were evaluated through microstructure characterization, me- chanical testing and scanning electron microscope analysis of fracture surfaces. Conclusions • The T-Mag and ablation processes produced the best castings according to defect and fracture surface analysis.
• According to an analysis of four- point bending testing, T-Mag cast-
ings exhibited better mechanical properties than squeeze cast and LPPM parts.
• Castings made in the ablation process presented higher ductility than the other processes. None of the ablation samples could be broken through four-point bend- ing testing.
• Squeeze casting produced fine dendrites, T-Mag yielded the larg- est average grain size, and LPPM and ablation produced similar grain size distributions.
• Significant amounts of shrinkage porosity and oxide film defects were found in the squeeze cast and LPPM samples.
Casting Vs. Wrought In “Solidification and Heat Treat-
This end-chilled mold was used in the study of 6061 and 6082 alloys used in metalcasting.
May/June 2011
The effects of heat treatment in produc- ing wrought-type alloys in near-net-shape casting were studied using this suspension link casting.
ment of 6061 and 6082 Alloys for Use in Shape Casting,” a team of research- ers set out to see if two aluminum alloys that are typically worked me- chanically to produce the desired final component shape and properties (e.g. wrought materials) could be casting to shape and heat treated.
Metal Casting Design anD PurChasing 43
asked by the more than 150 presenters at the 115th
Metalcasting Congress, held
April 5-8 in Schaumburg, Ill. They were also among the questions asked in the presentations receiving the highest marks by their peers. Following is a look at the questions
posed and conclusions reached in three presentations receiving perfect (or nearly perfect) scores from their panel of peer reviewers.
hat is the best way to cast magnesium? Can metal castings exhibit the material
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