International meeting updates technology, stresses need to reach casting specifiers.

"Austempered ductile iron, if engineered, produced, processed and implemented properly, is a remarkable material. A well-conceived application presents an opportunity for broader ADI use. if ill-conceived and hastily implemented, however, potential markets may be closed for years."

With these words, John R. Keough, head of Applied Process, Inc., summed up the limiting prospects of austempered ductile iron for those who attended the 1991 World ADI Conference on March 12-14 in Bloomingdale, illinois.

Like other speakers, he detailed ways to improve ADI metallurgy, production and quality, and, thus, extend the range of the metal's applications. ADI has grown from a laboratory curiosity to a competitive engineering material successful in automotive, agricultural, construction, mining, military, railroad and industrial components, Keough said.

However, much needs to be done to attract the attention of design engineers and casting specifiers to the long-range benefits provided by ADI parts, he added.

The ADI meeting, which attracted representatives from 20 countries, underscored the importance of austempered ductile iron as an engineering material and increasingly as a competitor of other cast and forged products.

To further reinforce ADI's acceptance as a casting material, Robert Christ of Deere and Co. reported the June 1990 publication of ASTM specifications that establish National Standard Specifications for five strength grades of austempered ductile iron.

In his keynote address, Karl B. Rundman of Michigan Technological University said obvious forces promoting ADI growth include a rising demand for a higher duty material, user education aimed at establishing the quality and consistency of ADI, and expanding the industry's capacity to produce it.

ADI demand, he said, will come from a need by designers for higher-performance metal components. Ultimately, market penetration will be sustained only by tight controls and limits on alloy content, solidification processing and heat treatment. The ideal production scenario for ADI, Rundman said, would be for the casting supplier to dedicate melting ADI grades with a captive heat-treat facility.

The large number of applications attractive for austempered ductile iron are those requiring higher strengths and ductilities than are normally attainable in other grades of ductile iron, he said. These applications traditionally have gone to other ferrous materials, such as steel castings and forgings or welded steel fabrications.

The demand for ADI will come from designers selecting materials to meet physical, mechanical and economic specifications, Rundman concluded.

ADI use is growing because the material demonstrates a good combination of strength, toughness and wear resistance. Since ADI is 10% lighter than steel and is a cast iron, the buyer can benefit from near net shape manufacturing and lower energy consumption per pound. Because ductile iron now enjoys a widening producer base, competition will continue to push ADI technology to extend production efficiencies and user economies.

The conference cited the fact that ADI already is replacing some steel forgings and castings by virtue of its excellent properties and relatively low manufacturing cost. Applications are diverse and include: * railroad wheels, suspension parts,

covers, latches, shoes, tie bars and

track hardware; * agricultural parts, such as plow and

tillage points, chisels, sickle guards,

tie rods, slip clutches, hitches, pins,

fertilizer knives and power take-off 

components; * military ordnance, armor, track and

assorted vehicle components; * construction and industrial parts such

as digger teeth, slides, yokes, collars,

structural members, sprockets, highway

and pole line hardware, connectors,

track plates and shoes, end connectors,

housings, gears, crank and

camshafts, snow plow shoes and

pump parts; * automotive camshafts and crankshafts,

timing gears, connecting and

tie rods, suspension arms, differential

gears, brake components, CV joints,

drive yokes and pump components.

ADI applications also are on the rise in Europe and the Far East. Filip Defoirdt, research and development manager for Ferromatrix of Belgium, reported that drive mechanism parts for industrial weaving looms are now being made from ADI. They are replacing high-carbon, surface-hardened, through-hardened and case-hardened steel castings.

Wei Bin-Qing of the mechanical engineering department at Tsing Hua University, Beijing, China, discussed the success in manufacturing grinding balls using ductile iron as a wear-resistant substitute for more costly high-chrome, white-cast iron. The ADI balls were reported to have a 1.5-2 times greater impact fatigue advantage and a production cost half that of high-chrome balls.