Crystalline Phase Changes due to High-Speed Projectiles Impact on 304L Steel

Abstract

Abstract The physical characteristics and molecular structure of 304L steel are well known; however, little is known about the high-velocity impact on this metal. The effects of high-speed velocity impact on the crystalline structure and material phase changes are studied experimentally. The effects of an impact on the crystalline structure are assessed by impacting 304L steel plates with Lexan projectiles. A two-stage light gas gun accelerates projectiles to a velocity of 6.58 km/s at the point of the impact. The impacted plates’ surfaces are inspected using the Electron Back Scatter Diffraction (EBSD). Nine regions are examined and analyzed. These regions are selected from the area immediately under the impact crater to locations not physically affected by the impact. Observations of collected EBSD images show that the predominant phases are Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC). A Hexagonal-Close-Packed (HCP) phase is also indexed. Since these crystalline structures are the most expected lattice formations, the samples are post-impact examined for molecular structure allocation changes. In this study, traces of HCP were found at some locations in all post-impact stages. This study also indicates that the FCC crystalline structure remained the dominant phase after impact. 304L steel iron alloys show resistance to phase changes behavior under high pressure shocks even close to the crater and impact holes.