Abstract

This specification covers ductile iron castings that are subsequently heat treated by an austempering process. The chemical composition requirements may be agreed upon between the manufacturer, heat treater, and the purchaser. Requirements for the microstructure constituents such as graphite, ausferrite (acicular ferrite and high carbon, stable austenite), pearlite, and martensite are prescribed. The iron shall conform to the mechanical property requirements including tensile strength, yield strength, elongation, impact energy, and Brinell hardness. Castings shall be heat treated by an austempering process detailed in this specification. The standard specimens for tension and Charpy impact tests are illustrated.

This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.

1. Scope

1.1 This specification covers ductile iron castings that are subsequently heat treated by an austempering process as defined in 10.1.

1.2 The application of the austempering heat treatment extends the range of properties achievable in ductile iron castings.

1.3 No precise quantitative relationship can be stated between the properties of the iron in various locations of the same casting or between the properties of castings and those of a test specimen cast from the same iron (see Appendix X1). However, austempering heat treatment will tend to diminish any differences in mechanical properties.

1.4 The production of castings, machining (if required), and the austempering heat treatments may be performed by different manufacturers, as covered in Section 15. The purchaser should establish by contract agreement, at the time of ordering, the responsibility of the various parties for meeting the specification requirements.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5.1 Exception Within the text, the SI units are shown in brackets.

2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

ASTM Standards

A247 Test Method for Evaluating the Microstructure of Graphite in Iron Castings

A370 Test Methods and Definitions for Mechanical Testing of Steel Products

A732/A732M Specification for Castings, Investment, Carbon and Low Alloy Steel for General Application, and Cobalt Alloy for High Strength at Elevated Temperatures

A834 Specification for Common Requirements for Iron Castings for General Industrial Use

E8 Test Methods for Tension Testing of Metallic Materials

E10 Test Method for Brinell Hardness of Metallic Materials

E23 Test Methods for Notched Bar Impact Testing of Metallic Materials

Military Standard

Keywords

Ausferrite; Austempering; Ductile Cast Iron; Hardenability; Heat Treatment; Proeutectoid Ferrite; Austempered ductile iron castings--specifications; Ductile iron castings--specifications

ICS Code

ICS Number Code 77.140.80 (Iron and steel castings)

DOI: 10.1520/A0897_A0897M-06R11

ASTM International is a member of CrossRef.

ASTM A897 / A897M