Timeline of ductile iron history.

From Millis' research activities in the 1940s to this year's 50th anniversary of its announcement, ductile iron's road has been paved by growth and advancement.

Imagine if there wasn't a chromium (Cr) shortage in the 1940s. Imagine if a young metallurgist named Keith Millis didn't work for the International Nickel Co. (INCO). Imagine if Millis didn't work on a research assignment to develop an alternative to Cr alloy addition for the manufacture of wear-resistant iron. If these events never happened, it is feasible the advancements made possible by spheroidal graphite cast iron via magnesium (Mg) would never have happened.

But there was a need to develop an alternative for Cr in the production of wear-resistant iron, and there were Millis and his colleagues, who in the pursuit of their goal discovered that a spheroidal graphite shape could be produced with proper Mg additions to molten iron.

Mother Nature may provide the inherent benefits of high strength, ductility, impact and fatigue life associated with spheroidal graphite shape. However, it was the detailed work of Millis that provided the method of coercing the graphite in cast iron to take the form of spheroids. Once this method was established, it not only energized an existing industry, but created a new one that today is called by many as the ductile iron industry.

Following is a timeline of some of the significant advancements and events that have occurred in the ductile iron industry - before, during and since its inception.

1943 - Throughout most of the 1940's, Millis worked for INCO at its Bayonne, New Jersey labs as a research metallurgist on a project to find a replacement for Cr in the production of wear resistant iron. In 1943, Millis discovered that the use of a Mg alloy in molten iron produced spheroidal graphite structure.

1948 - On May 7, at the AFS Casting Congress in Philadelphia, Henton Morrogh of the British Casting Research Institute Assn. (BCRIA) presented a paper discussing the use of cerium (Ce) to produce spheroidal graphite structure in cast iron. During this presentation, INCO announced work in its research laboratory that used Mg to produce spheroidal graphite.

1948 - The open ladle treatment method was the first method used to introduce Mg to molten iron. Its popularity prevailed through several decades. By 1967, 65% of ductile iron foundries reported using this method for production.

1948 - On June 14, Jamestown Malleable Iron, a division of Blackstone Corp., poured the first non-laboratory ductile iron casting. The casting was a huge test bar, approximately 66 in. long, varying in metal thickness from 2-6 in. and weighing about 1300 lb.

1948 - On December 20, Cooper-Bessemer, Grove City, Pennsylvania, became the first INCO licensee for the production of ductile iron using Mg.

1948 - Quick to experiment with this new material, the first ductile iron pipe was cast at Lynchburg Foundry, Lynchburg, Virginia. Lynchburg Foundry was the second INCO licensee.

1949 - On February 4, the first commercial heat of ductile iron was poured at Cooper-Bessemer. Poured were keel blocks, diesel engine parts, a pressure cylinder, an 8-in. cube and two cylinder liners.

1949 - The first ASTM specification for ductile iron was written and issued. The original specification was ASTM A339-51T, which was later replaced by ASTM A 536.

1949 - The development of magnesium ferrosilicon (MgFeSi) alloy made iron treatment easier.

1949 - A U.S. patent on ductile iron production based on molten metal treatment with Mg was granted to Millis, Albert Gagnebin and Norman Pilling of INCO. This remains the primary process used today.

1949 - Ford Motor Co. began pilot operations for ductile iron.

1949-50 - Professor Howard Taylor of the Massachusetts Institute of Technology, Boston, organized the first ductile iron conference, which paved the way for the acceptance of the ductile iron industry.

1950 - Ford Motor Co. introduced stack molding of ductile iron rocker arms, which utilized the ability of ferritic ductile iron to be coined to final dimensions.

1951 - One year after the first production application, Ford converted 100% of its crankshaft production to ductile iron.

1955 - Spurred by People's Gas Co., Chicago, which began installing ductile iron gas mains, ductile iron pipe was first introduced to the marketplace. That year, 500 tons of ductile iron pipe were produced. By 1997, 1.75 million tons of ductile iron pipe were being produced in the U.S.

1955 - From 1955-1975, the ductile iron industry was characterized by almost explosive research and publication of knowledge.

1957 - John Deere Co., East Moline, Illinois, started making ductile iron castings as prototypes for various applications in an experimental foundry.

1957 - Pressure chambers and pressure ladles were introduced to the ductile iron industry. Although these methods had the cost advantage of using pure Mg and obtaining good recoveries, the high capital and operating cost associated with this process resulted in virtually no application of this method in the U.S.

1957-60 - In the late 1950s, Morrogh discovered that additions of Ce and other rare earth elements nullified the influence of subversive residual elements that caused spheroidal graphite to degenerate into flake graphite. This led to the development of several new charge materials that made production of as-cast ductile iron possible.

1958 - U.S. ductile iron shipments exceed 100,000 tons.

1958 - Desulfurization in a shaking ladle was developed in Sweden.

1958 - The Ductile Iron Society (DIS) is formed as an association dedicated to further research and the free exchange of ductile iron technology.

1959 - This year marked the start of rapid growth in the demand for ductile iron castings. In 1960, 250,000 tons of ductile iron castings were shipped.

1960 - John Deere built a ductile iron addition to John Deere Malleable Works. Ductile and malleable iron were poured side by side until 1968, when ductile iron replaced all malleable iron.

1960s - Coreless electric furnace melting of ductile base iron became rapidly accepted due to stringent requirements for chemical and temperature control in ductile iron production.

1960s - Early in the decade, the injection method for nodularizing iron was introduced. This method utilizes a hollow graphite or refractory tube to introduce a powder or granular nodularizing material conveyed by an inert gas to below the metal surface. High maintenance cost and fume emissions limited its popularity.

1960s - In the early part of the decade, the sandwich method for ductile iron production was introduced. This was similar to the open ladle method, but used a 1-2% addition of steel punchings or FeSi alloy cover over the nodularizing alloy. The use of cover resulted in substantial Mg recovery when compared to the open ladle method and quickly became the popular choice of treatment.

1960s - GM undertook fleet testing of austempered ductile iron (ADI) differential gears on taxicabs and achieved excellent results.

1961 - Chevrolet conducted its first ductile iron heat at Chevrolet Grey Iron Foundry in Saginaw, Michigan. Chevrolet then built a ductile iron experimental foundry in April 1962 and its first production foundry in November 1962.

1962 - In March, Ingersoll Milling Machine Co., Rockford, Illinois, sources the largest ductile iron casting produced at the time, a 147,000-lb crossrail for a milling machine.

1962 - Wagner Castings Co., Decatur, Illinois, developed a process and began commercial production of high volume, thin section ductile iron castings "as-cast."

1962 - American Cast Iron Pipe Co. (ACIPCO), Birmingham, Alabama, introduces the Mag-coke process of producing ductile iron, which was one of the first pure Mg treatment methods. Mg impregnated metallurgical coke was used in the plunging treatment of ductile iron.

1963 - Chevrolet's ductile iron crankshaft becomes GM's first ductile iron production part.

1964 - The plunging treatment method utilizing a refractory bell containing the nodularizing agent to deeply submerge the agent into a ladle of molten metal was developed. This process resulted in excellent Mg recoveries and magnesium vapor and fume reduction.

1964 - Lynchburg Foundry's Radford, Virginia plant installed the first two "shaking ladles" in the U.S.

1964 - Bill Dell and Bob Christ, John Deere and Co., present a paper on mold inoculation that spurs the development of many of today's forms of mold and late stream inoculation.

1965 - The first national standards for ductile pipe were enacted by ANSI.

1965 - GM's Central Foundry began producing ductile iron crankshafts at its Danville, Illinois plant.

1965-67 - GM designed and built new ductile iron foundries in Saginaw, Michigan and Defiance, Ohio.

1966 - John Deere designed its ductile iron foundry in East Moline, Illinois, which started-up in late 1968.

1966 - The porous plug method of ductile iron production was introduced as an extension of porous plug desulfurization. This method was primarily suited for batch sizes between 1500 and 6000 lb.

1966 - The tilt reactor treatment method, which required complex equipment and pure Mg, was introduced. This method provided good recoveries, the ability to use low cost Mg, the ability to desulfurize the base iron and the flexibility to simultaneously add carbon.

1966 - INCO's patent for producing ductile iron expires. At this time, there were 651 licensees in 31 countries who produced 2,074,868 tons of ductile iron.

1966 - 5% MgFeSi alloy is tested at Chevrolet and proven successful when compared with the performance of 9% MgFeSi alloy.

1968 - U.S. production of ductile iron castings exceeds 1 million tons and surpassed that of malleable iron.

1970 - The first experimental holding of fully treated ductile iron was conducted. Some limited applications are still used today.

1970 - The first "as-cast" ductile iron connecting rods for passenger cars were made by Wagner Castings.

1970 - A ductile iron steering knuckle, a critical safety item, is introduced on Chevrolet's Cadillac automobile.

1970s - Dynamic tear testing was developed to understand the dynamic properties of ductile iron.

1970s - Early in this decade the production of ductile iron using the in-mold treatment method was developed. This method was developed in England, but Woody Holden, Pickands Mather, brought it to the U.S. The process incorporates a special reaction chamber within the runner and gating system of the mold. The nodularizing agent is placed in the chamber and spheroidizing occurs during the pouring process. Extremely high Mg recoveries and very little Mg vapor fumes or slag are formed.

1970s - This decade marked the development of "as-cast" and subcritical annealed ductile iron steering knuckles for automotive and track applications.

1970s - Ultrasonic verification of nodularity was developed.

1970s - Largely through the efforts of Mike Lalich, Foote Mineral, in the development of thin-cast MgFeSi alloy, the consistency of the treatment alloy significantly improved. Consequently, the quality of all ductile iron castings using these alloys also significantly improved.

1971 - U.S. ductile iron production exceeds 2 million tons and surpasses cast steel production.

1972 - The first production application of ADI was recorded. This was a 1-lb crankshaft for a hermetically sealed refrigerator compressor cast by Wagner Castings (designed and engineered by Tecumseh Products).

1973 - GM Central Foundry Div. alone reports 1 million tons of ductile iron castings have been shipped since 1965.

1973 - The 25th anniversary luncheon program was held at the 77th AFS Casting Congress in Montreal to pay tribute to ductile iron and the people who developed and marketed the technology.

1975 - In October, DIS and AFS hosted the first Joint Conference on ductile iron.

1975-present - This era marks a period of expanding the technical understanding and production of ADI.

1976 - Acid-slag cupola practice plus external desulfurization with calcium-carbide (Ca[C.sub.2]) begins to replace basic slag cupolas. Early cupolas used acid and soda ash to desulfurize. Because of environmental and quality reasons, cupolas producing ductile iron base metal were converted to basic operations.

1977 - GM installs ADI rear differential sets in passenger cars.

1978 - U.S. ductile iron casting shipments exceed 3 million tons.

1979 - The converter or tilt reactor method for producing ductile iron favors the use of higher sulfur found in cupola melting.

1979 - The Cast Iron Pipe Research Assn. members changed their name to the Ductile Iron Pipe Research Assn. (DIPRA) since production had entirely converted to ductile iron.

1979 - In the late 1970s and early 1980s. the European Flotret and Sigmet methods of producing ductile iron were introduced in the U.S.

1980 - The first ultra modern foundry was completed in Italy by FIAT for exclusive production of ductile iron castings using the in-mold process.

1980s - The tundish ladle is embraced by industry as the favored method of nodularizing ductile base iron. It offers excellent Mg recoveries and fume control.

1950s - The Mg wire injection method of treating ductile base iron with Mg powder is tested in the late 1980s and gained greater popularity in the mid-1990s.

1980s - Calcium-oxygen/calcium-fluoride (CaO/Ca[F.sub.2]) (Lime/Spar) method of desulfurizing cupola-melted ductile base iron begins to replace the Ca[C.sub.2] method.

1990 - DIPRA celebrates its 75th anniversary.

1990s - Wire inoculation in conjunction with automatic pouring of ductile iron was first used in production.

1990s - This decade marks the rapid development, acceptance and growth of ADI. Shipments of ADI castings in the U.S. are expected to reach 80,000 tons by 1998.

1994 - U.S. ductile iron casting shipments exceed 4 million tons.

1998 - This year the foundry industry celebrates the 50th anniversary of ductile iron's announcement and the 40th anniversary of DIS.

Sources

K.D. Millis, The Status of Ductile Iron Today, AFS-DIS (1975). S.C. Clow, Ductile Iron in the Pipe Industry, AFS-DIS (1975). W.S. Williams, Ductile Iron in a Jobbing Foundry, AFS-DIS (1975). C.R. Loper, The Origin of Ductile Iron - Part I and II, Foundry Management & Technology (November and December 1994). modern casting (May 1973). Audiotapes from the Ductile Iron Luncheon at the AFS Casting Congress in Montreal. Various publications from the AFS Library. Special thanks to: Richard Bonds, Ductile Iron Pipe Research Assn.; Bob Christ, John Deere and Co.; Lyle Jenkins, Ductile Iron Society; Bill Henning, Miller & Co.; John Keough, Applied Process, Inc.; Roy Lobenhofer, Lobenhofer Consulting, Inc.; Carl Loper, Univ. of Wisconsin; P.H. Mani, Internet's Wagner Castings Co.; Gene Muratore, Rio Tinto Iron & Titanium America.

RELATED ARTICLE: INCO-Ford Trial of 1956

Another event of no small consequence in the big picture of ductile iron development was the 27-day INCO-Ford trial in 1956, eight years into the lifecycle of ductile iron. INCO enacted a suit against Ford Motor Co. and the Caswell Co. (Ford dealership) in New York for "the willful and deliberate infringement by manufacture, use and sale of nodular (ductile) iron crankshafts." According to then INCO employee and trial witness Ken Kirgin, "The trial put the licensing system on the line. Had Ford won, the system would have dissolved." According to Kirgin, Ford claimed that the Mg levels it was using were below what INCO stated in the patent. Meanwhile, INCO believed the patent covered any level effective in changing the graphite in the iron from a flake to spheroidal shape. Ford denied infringement and claimed that the practice was prior art.

"While we had not expected this to happen because of the uniqueness of the invention, we were aware that nearly all valuable patents are put to the test of litigation," wrote INCO's Albert Gagnebin in a 1973 modern casting article. "The defense of our position consumed an enormous amount of time and money." It is important to note that from 1949-1955, INCO had spent $775,273 to promote its licensing program, yet it had received only $705,010 in royalties.

The trial, which included a trip to Cooper-Bessemer, Grove City, Pennsylvania, to witness the process, included 2400 pages of transcripts, 21 witness testimonies and trial briefs exceeding 450 pages. Special Master Simon Rifkind concluded that Ford and Caswell had infringed against INCO, and its licensing system remained intact. "Had INCO lost ductile iron would not have grown as quickly as it did," said Kirgin. "INCO used the royalty system to provide for the important and extensive research needed as well as development of the process and applications."

Kirgin said Ford did not harbor ill feelings following the verdict. "I was the first INCO representative sent to see them - one week after the trial concluded," he said. "I found nothing but friends there."

Michael J. Lessiter, editor