This practice covers the requirements for the heat treatment of aluminum alloy castings from any casting process such as investment casting, permanent mould casting, sand casting, and others. It excludes castings that are used in specific aerospace applications or those made from wrought aluminum alloys. The aluminum alloys should be subjected to controlled heat treatment using the usual air chamber furnace or other heating media like lead baths, oil baths, fluidized beds, or even superheated steam. Air chambers may be oil or gas fired or may also be electrically heated but the atmosphere inside each should be controlled to prevent porosity. Quenching is normally performed by immersing castings in a hot-water bath. It is important that the furnace be calibrated before it is used initially and after any change in the furnace. Likewise, temperature-measurement systems should be regularly checked for accuracy.

1.1 This practice covers, when specified by material specification or purchase order, the heat treatment of aluminum alloy castings from all casting processes.

1.1.1 The heat treatment of aluminum alloy castings used in specific aerospace applications is covered in AMS 2771 and specific AMS material specifications.

1.1.2 The heat treatment of wrought aluminum alloys is covered in Practice B918.

1.2 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.

1.2.1 SI Units—The SI units are shown in brackets or in separate tables.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.