Metallurgical Failure Analysis of the M230 Machine Gun Barrel - MIF-A- 001-1999-I

摘要

On 7 October 1998, an Apache Longbow Helicopter (AH-64D Longbow, 97- 05031) crashed at Ft. Hood, Texas due to the rupture of the 30-mm M230 machine gun, which is attached to the front of the aircraft. The rupture was caused when the projectiles exited through the walls of the barrel, creating two holes approximately 20 to 23 in. up from the gun chamber. The gun was removed from the helicopter and sent to TACOM-ARDEC for a metallurgical evaluation and failure analysis. Results from the evaluation show that the gun barrel had failed due to exposure to excessive heat. The change in the original steel microstructures from tempered martinensite to bainite and untempered martensite, coupled with the increase in steel hardness in the area where the projectiles exited, supports the theory that the steel had reached or exceeded the austenitizing temperature at the time of failure. This made the barrel very weak and allowed the projectiles to exit through the walls of the barrel.