The 2008 Keith Millis Symposium on Ductile Cast Iron cosponsored by DIS and AFS was held at the Orleans Hotel & Casino in Las Vegas on October 20 – 22, 2008.  Approximately 200 attendees from the international community attended 2 ½ days of presentation related to ductile iron (DI), austempered ductile iron (ADI) and compacted graphite iron (CGI).

The conference began with a day of presentations concerned with markets for ductile iron as well as applications.   Day 2 of the conference began with the keynote address, “Modified Graphitic Iron – Now What Do We Do With This Stuff?” by Dr. Preston Scarber. Presentations on production, processing and properties of DI were also delivered.

SUMMARY of DAY 1

Alfred Spada (AFS), Patricio Gil (Blackhawk de Mexico) and Chandra Rajan (FOSECO) summarized how the US ductile iron industry is competing in a global market.  2008 and 2009 are forecasted to be low production years; however, steady growth is expected across the industry starting in 2010 and to continue for at least 7 years.  Argentina, Brazil and Mexico were cited as good and growing manufacturing options for North America with Mexico having a 20% lower manufacturing cost.  Figure 1  summarizes imports to the US by country in 2008.

Figure 1:  Pie chart showing the countries of origin for importing castings into the U.S.

Kerui Li (China Foundry Institute) provided information about the history and status of production of ductile iron in China.  China is the current world leader in tonnage produced of ductile iron. The wind power generation industry is growing at a rapid pace and demands for large, heavy section castings are increasing.  Producers in China are working diligently to solve the challenges associated with producing high quality ductile iron that meets the stringent requirements for wind power applications.

Papers describing the historical development of CGI and ADI were presented by Dr. Steve Dawson (SinterCast) and John Keough (Applied Process Inc.), respectively.  Both presentations included information about applications of these materials along with the potential for the future of CGI and ADI.

Additional papers on applications of ADI were presented by Dr. Arron Rimmer (ADI Treatments), Eugene Muratore (Rio Tinto), Xia Yong (AP Suzhou) and Enrico Veneri (Zanardi Fonderie).  Among the applications featured were a cross-link for a rear end suspension system, a wind turbine planetary gear carrier, rack & pinion gears, pattern tooling and crankshafts for four-cylinder diesel engines. 

 Figure 2: An ADI wind turbine planetary gear carrier.

Enrico Veneri described a new microstructure that has been developed by Zanardi Fonderie. – perferritic isothermal ductile iron.  This patent pending material is an intermediate grade between pearlitic ductile iron and ADI.

Dr. Roberto Boeri (INTEMA) described ongoing research to understand the embrittlement of ADI and high strength ductile iron when exposed to liquids.  He noted that this only happens when 3 conditions are simultaneously met:  presence of a liquid, applied stress near yield and a slow strain rate.  Recent work has focused on painting and coating to provide a barrier to contact with liquids.  Preliminary results have shown that it is difficult to maintain the integrity of the coating during deformation.

Chantal Labrecque (Rio Tinto) presented a comprehensive literature survey on the status of thin wall ductile iron casting technology.  State of the art practices for production of ductile iron can now produce high quality castings with a 2 mm wall thickness.

SUMMARY of DAY 2

Dr. Preston Scarber’s (University of Alabama-Birmingham) keynote address featured, “Modified Graphitic Iron – Now What Do We Do With This Stuff?”  This presentation demonstrated how simulation and real-time x-ray can be used to better understand the processing variables that affect casting quality.  Ductile iron and CGI can be used in many high stress applications without needing to be twice as thick as other ferrous castings.

Dr. Alan Druschitz (University of Alabama-Birmingham) described preliminary efforts to investigate low carbon equivalent ductile iron.  Cees van Eldijk presented information on applications of thin wall ductile iron (TDI) with a section thickness just under 2 mm.  Figure 3 illustrates a TDI design for a shock absorber bracket.

Figure 3: Shock absorber bracket; a TDI design provides a smoother stress distribution and ~50% weight reduction vs. a steel weldment.

Information about production/processing of ductile iron was presented by Hans Roedter (Rio Tinto), Dr. Rudolf Sillen (NovaCast Technologies AB), Christof Heisser (Magma Foundry Technologies), Dr. Jorge Sikora (INTEMA), Al Alagarsamy (Consultant) and Noberto Rizzo (Dana Corporation).  Topics covered included:  gating & risering, relating the true eutectic point to process control of ductile iron, autonomous optimization of ductile iron castings, solidification macrostructure of free graphite cast iron, reheating ductile iron and how nodule density is related to casting yield in ductile iron.

Compacted graphite iron was featured in 2 papers.  Frans Mampaey (Sirris) described the use of oxygen activity measurements to determine graphite structure.  David Poerschke (Case Western University) presented preliminary results from his graduate studies that are concerned with the effects of cooling rate on the microstructure, mechanical properties and machinability of CGI.  

SUMMARY of DAY 3

Robert O’Rourke (Wells Manufacturing – Dura Bar Division) discussed dry slidingwear characteristics of ductile irons.  This data is of use when DI rubs against other metal parts with low interfacial pressures as would happen in hydraulic and other machine assemblies.

Gwendolyn Baker (TK-Waupaca) described how the application of poka yoke or mistake-proofing measures to detect and eventually prevent errors and failures in the ductile iron conversion process were implemented in a production foundry.  The impact of implementing this methodology has resulted in a dramatic decrease in the amount of ductile iron from suspect conversions being poured into molds.

Dr. Richard Larker ( Indexator AB ) discussed ferritic ductile iron that has been solution strengthened by silicon.  Misconceptions about the role of Si in ductile iron were presented.  The results of the author’s investigations suggest that the loss of toughness in ductile iron may be related to Mn content rather than Si.  Figure 4 shows a swivel housing that was converted to solution strengthened JS/500-10 in 2005.

Ian Lee (Graham Campbell Ferrum) and Chris Samuel (University of Alabama-Tuscaloosa) discussed topics related to heat treatment of ductile iron.  Topics covered included criteria for heat treatment of ductile iron gears and the use of gleeble dilatometry for the determination of CCT curves.

The conference concluded with a discussion of machinability of ductile iron by Dr. Robert Voigt (Penn State University).  The influence of casting dimensional variability on tool life variation was presented.

Figure 4:  An ISO 1083/JS/500-10 swivel housing. Use of this grade of high Si ductile iron results in consistent properties and 20 ΅m tolerances.

FURTHER INFORMATION

Copies of the conference proceedings are avai lab le for purchase from the American Foundry Society at www.afsinc.org.

ACKNOWLEDGMENTS

The DIS would like to acknowledge the following individuals who volunteered their time to make the 2008 Keith Millis Symposium on Ductile Cast Iron a success:

Conference Planning Committee

Kathy L. Hayrynen
Programming Chair
Applied Process, Inc.

Al Alagarsamy
Consultant

Alfred Spada
American Foundry Society

Eugene Muratore
Rio Tinto Iron & Titanium

James Wood
Ductile Iron Society

Martin Gagne
Rio Tinto Iron & Titanium

Prem Mohla
Hickman Williams & Co

Scott Gledhill
TKA-Waupaca

Scott Lammers
American Foundry Society

Thomas Prucha
American Foundry Society

Tony Thoma
Wescast Industries

Vasko Popovski
Chair, Castings Display Subcommittee
Applied Process, Inc.