Austempered ductile iron, or A.D.I. as it is commonly called, is a relatively new member of the ductile iron family. The properties of A.D.I. are achieved through a special heat treating process. This sophisticated heat treatment requires a cycle of heating and salt bath quenching at precise times and temperatures. The resulting material has a combination of exceptional strength and toughness, often exceeding that of alloy steels. The special processing for A.D.I. provides a material which does NOT contain embrittling carbides, unlike steels which must derive their strength from the presence of carbides. A.D.I.'s unique properties, in conjunction with ductile iron's superior castability, results in a material which can be used to cast complex shapes, with a greater certainty of consistent quality, superior cosmetics, and tolerance control when compared to steel.
The A.S.T.M. specification A897 is now the most commonly accepted specification for Austempered Ductile Iron. The five grades specified are detailed in the table below. They are most readily differentiated by their hardness; however, tensile, yield and elongation values are also specified.
Lethbridge Iron Works works closely with a leading heat treater to provide this value added service. Please contact Bart Davies if you require any further information on this new and exciting material.
| AUSTEMPERED DUCTILE IRON ASTM A897 - 06 (castings of this specification are heat treated by an austempering process) |
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| Grade | Min. Tensile (psi) | Min. Yield (psi) | Elongation (%) | Typical HBW |
| 110-70-11 | 110,000 | 70,000 | 11 | 241 - 302 |
| 130-90-09 | 130,000 | 90,000 | 9 | 269 - 341 |
| 150-110-07 | 150,000 | 110,000 | 7 | 302 - 375 |
| 175-125-04 | 175,000 | 125,000 | 4 | 341 - 444 |
| 200-155-02 | 200,000 | 155,000 | 2 | 388 - 477 |
| 230-185-01 | 230,000 | 185,000 | 1 | 402 - 512 |
 September 6, 1999 To Whom It May Concern Established in 1984, Tiger Tool International Incorporated has and continues to specialize in the design and manufacture of several unique specialty tools focused primarily on the Heavy Duty Equipment industry. Over the years Tiger has gained considerable experience in the use of various ferrous metals and casting techniques for use in the development and production of its products. Until recently, one of the greatest challenges faced by Tiger has been the procurement of quality castings having sufficient strength characteristics, consistent tolerance minima, exceptional casting definition and cost effectiveness. The discovery by Tiger of Austempered Ductile Iron (ADI) has been significant. ADI has not only met, but also surpassed all of our expectations. The truth is, we wish we could keep ADI a secret from the rest of the world! "The value of gold can be depreciated in the hands of a fool." Any company that relies on the delivery of quality castings as an integral part of their business will attest to the high level of frustration one can experience while working with many foundries. Lethbridge Iron Works (LIW) has clearly been an exception to this rule. LIW is organized, well managed and operates a state-of-the-art facility that any company would be proud to be associated with. Notwithstanding other financial advantages, I believe that having gained the knowledge of ADI, in addition to having connected with LIW, has added to the good-will of our business. Sincerely, Ken Jansen |
