ASTM 897 Grade 4 (200-155-01), Austempered Ductile Iron

Subcategory: Ductile Iron; Alloy Cast Iron; Metal

Key Words: ADI; ASTM 897 Grade 4

Material Notes:
ASTM 897 (in-lb units) 200-155-01
ASTM 897M (SI units) 1400-1100-01. The values below are typical properties, not guaranteed minimums.

Austempered Ductile Iron (ADI) offers low cost, design flexibility, good machinability, high strength-to-weight ratio and good toughness, wear resistance and fatigue strength because it can be cast like any other member of the Ductile Iron family, thus offering all the production advantages of a conventional Ductile Iron casting. Subsequently it is subjected to the austempering process to produce mechanical properties that are superior to conventional ductile iron, cast and forged aluminum and many cast and forged steels.

The mechanical properties of Ductile Iron and ADI are primarily determined by the metal matrix. The matrix in conventional Ductile Iron is a controlled mixture of pearlite and ferrite. (Tempered martensitic matrices may be developed for wear resistance, but lack the ductility of either as-cast Ductile Iron or ADI). The properties of ADI are due to its unique matrix of acicular ferrite and carbon stabilized austenite; called Ausferrite. ADI is a group of materials whose mechanical properties can be varied over a wide range by a suitable choice of heat treatment, as seen in the various entries in MatWeb.

The composition reported herein does not guarantee ADI properties, nor is it mandatory. However, this composition is a typical, industrially successful ADI composition. A good controlled chemistry like this one combined with a consistently high nodule count and nodularity and a consistent pearlite/ferrite ratio in clean, shrink-free Ductile Iron will provide the most robust process for the production of ADI.

Information supplied to MatWeb by Applied Process, Inc.