Metallurgical analysis of an aluminum sabot fired in the cannon caliber electromagnetic gun (CCEMG)

An aluminum 7475 alloy sabot fired from the Cannon Caliber Electromagnetic Gun (CCEMG) was metallurgically characterized. More melting was seen on the rear contact surface than the front and bubbles and cracks due to high-temperature oxidation (HTO) were observed. The hardness profile showed a decrease in hardness along the outer surfaces of the sabot, particularly the contact surfaces. The softening and the HTO suggest that the material was pushed past its melting point (477-635/spl deg/C). Cracks caused by overaging were found at the roots of the contact surfaces. Black residue found in the launcher was analyzed and found to be various compounds and nonstoichiometric compounds of aluminum and copper. These compounds did not oxidize.