Increasing Ballistic Resistance of Steel Body Armor by Hardfaced Coating

In this research, increasing the ballistic resistance of the steel armor body was done by Hardfaced Coating method. Welding on the sheet was done with a type of hard coated welding wire made of chromium, niobium-containing iron alloy and also a buffer type of manganese steel. After applying the hardened coatings on the steel sheets, the prepared samples were tested by impact ballistic test. Also, microstructural, hardness, elemental and metallographic analysis were done on the samples after the bullet impact. The thickness of the welded hard coating layer was measured as 8 ± 0.5 mm. The bullet penetration depth was measured as 0.5 mm in the sample with buffer and 1.5 mm in the sample without buffer. In surface hardened sheets, the fired bullet did not pass through the coated sheets. Buffer welding increased the ballistic resistance of the coated sheets against bullets. By forming a hard coating on the steel armor, a hard profile is created from the surface of the coating to the substrate, which plays an effective role in preventing the passage of bullets by creating appropriate flexibility. A composite structure consisting of martensite tempered with carbide particles that creates a hard area along with appropriate flexibility in the coating area, this structure can be the best structure for a coating on steel sheets to prevent bullet ballistic penetration. Cracks are created on the surface of the sample vertically and horizontally after the bullet hit, and these cracks are stopped inside the welding composite structure by chromium and niobium carbides. The mechanism for improving ballistic properties is to prevent crack growth on the weld surface. Surface hard welding with chromium and niobium iron alloy increases the ballistic resistance of steel sheets. Surface hardening coatings can be a suitable alternative to cost-effective methods of producing armor steels with high ballistic performance.