Aluminum Silver Anniversary Paper.

In his Silver Anniversary Lecture titled, "The Ductility Challenge: New Options for the Future," John L. Jorstad, JLJ Technologies Inc., explored the advancements in ductility in aluminum alloys over the last 20 years and offered some options for the future.

He began by looking at aftermarket wheels cast in the early 1970s and the stringent requirements placed on them by OEMs.

"There was no mystery in what was required to achieve ductility," Jorstad said. "Premium quality castings were the topic of the day. Many developed techniques and used them."

But today, newer techniques are needed to remain competitive. Jorstad offered two options--fluidized bed heat treating and sub-liquidous casting.

Fluidized bed heat treating allows metalcasters to achieve fully heat treated properties in short cycle times (about 15 min.). The theory behind the process is that rapid heating causes a different thermal expansion that fractures silicon, which spherodizes more rapidly.

Sub-liquidous casting is a semi-solid process that involves pouring into a shot sleeve and controlling cooling until the molten metal is 45-50% solid. The resulting casting can then be T5 heat treated without losing ductility.

According to Jorstad, ductility was a challenge in the 70s and continues to he today. But the tools for achieving greater ductility have improved and with emerging technologies, metalcasters will be able to offer better ductility at lower costs.