A Review on Gun Barrel Erosion

Abstract

The Erosion of Gun Barrels leads to reduced gun performance and availability, and increases the expense of barrel replacement over the life time of a gun system. Wear in gun barrel usually increases the bore diameter near the commencement of rifling. The wear spreads forwards toward the muzzle as the gun is fired continuously. The point of maximum wear remains near the commencement of rifling. Worn barrels are objectionable because they allow gas to escape past the shot thus reducing muzzle velocity, range and accuracy. As the muzzle begins to wear the shot loses directional stability. The total wear that can be tolerated is called condemning limit. Its value depends on the size of the gun, the required accuracy and the factor of safety that must be maintained against catastrophic fatigue failure. On average barrels are condemned when the bore diameter increases by about 5%. Wear depends not only on the thermal load but also on the surface metallurgy of the bore and the chemical interactions between the propellant gas and the bore surface. The erosivity of different propellants have been investigated over the years using various numerical methods and some works have tested propellants or propellant gases in some form of simulated gun. This paper discusses the various types of erosion taking place in the gun barrel. It also gives a list on various methods developed over the years to mitigate the gun barrel wear. Gun barrel erosion mechanisms include thermal, chemical, and mechanical factors. A 10% increase in bore temperature increases wear rate by 276%. Mitigation strategies include low flame temperature propellants and chromium plating.