GMW16867

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. The standard described herein measures the potential for aluminum to experience permanent growth due to metallurgical instability. Aluminum parts often operate at temperatures that facilitate phase transformation and precipitation of supersaturated alloying elements. These metallurgical changes may be accompanied by permanent volumetric expansion. Background on this phenomenon is given in Appendix A. Results of a benchmark study are presented in Appendix B.

Applicability. Aluminum alloys.

Remarks. Summary of test method: Ten right-circular cylinders with premeasured end-to-end lengths are heated at 250 °C for 100 h. After cooling to ambient temperature, each sample is remeasured with the change in length converted into percent (%) growth. Average and standard deviation(s) growth are calculated. Mean + 3s growth is defined herein as “Maximum Permanent Growth Potential” for the material and rated per Section 5.4 against a maximum allowance.