GMW16547

Description / Abstract: Introduction

Note: Nothing in this standard supercedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose. Test method to qualify a nodule, determine the degree of nodularity, nodule counts for graphite particles using a light microscope image of graphite in nodular cast iron.

Applicability. Nodular cast iron components used in automotive Chassis, Powertrain and other applications.

Remarks. For cast iron to be qualified as a nodular iron, a number of specifications including ISO 1083 stipulate that the metal shall contain 80% of graphite of certain form according to ASTM A247 or ISO 945. The descriptions of the graphite shapes are in a pictorial form in these standards and are used as a guide in rating the percentage nodularity. A repeatable test procedure that the casting suppliers and GM materials laboratories can use will greatly aid in accurate cast product evaluation.

This standard supercedes the currently used manual point-count method, which is labor intensive and requires many areas to be counted for a precise determination.