Strain Hardening and Strain-Rate Effect in Friction Between Projectile and Barrel During Engraving Process

The engraving of projectile is of great importance during interior ballistics when a gun is fired. In order to investigate the effect of loading speed on the engraving process, quasi-static and dynamic engraving tests are performed, respectively. Small caliber projectiles were engraved by using an MTS809 under predetermined low loading speeds and a specially designed gas gun-based test rig under high loading speeds. The hoop strain of the exterior surface of gun barrel during engraving process was measured. Surface morphology of copper jacket after engraving was observed. Microstructural evolution in cross section of copper jacket was investigated. The present study demonstrates the critical role of strain hardening at low loading speeds and strain rate effect as well as thermal effect at high loading speeds during the engraving process.