The influence of laser beam welding parameters (power, welding rate, focusing, head oscillation, shielding gas) on the microstructure, mechanical properties and corrosion resistance of the super-duplex stainless steel SAF 2507 was studied in this paper. The presented results clearly report the effects of welding parameter changes on the character of the steel’s microstructure. The presence of secondary phase M₂N in weld metals has an important influence on their mechanical properties. Optimal mechanical properties, an acceptable ferrite/austenite ratio, and the minimum content of M₂N nitride required in the weld metal were acquired in the case the following application: 1100 W power, welding speed of 10 mm/s, focusing of 4 mm, and pure nitrogen shielding gas (20 L/min).

This work investigated changes in the microstructure and local mechanical properties after the application of selected heat treatments to EN-GJL-300 grey cast iron. The main goal was to optimize heat treatment to achieve increased mechanical properties and subsequently wear resistance. The heat and heat–mechanical treatment were investigated by using a dilatometer as a physical simulator of treatment on real samples. Continuous cooling with three different rates and two other non-continuous treatments (austempering and ausforming) were used to treat the experimental samples. The research was focused on modification of the matrix microstructure, initially pearlitic. No change in the shape or morphology of the graphitic lamellae was required to preserve the damping properties. The results showed that, in terms of the specified conditions, heat treatment with continuous cooling at a rate of 10 °C s⁻¹ appeared to be optimal. This variant showed the presence of bainite and martensite in the microstructure with high hardness measured by nanoindentation as well as the optimal value of general Brinell hardness.

The development of modern types of ammunition and the increasing requirements for ballistic protection have created a need for armour systems capable of providing a high level of protection while maintaining an acceptable weight. Traditional homogeneous armour systems, primarily based on steel materials, have gradually become insufficient against high-velocity projectiles and shaped-charge munitions, leading to the development of multilayered and hybrid protective systems that combine materials with different mechanical properties. The aim of this review article is to systematically analyse the development of armour systems, from homogeneous metallic armour to modern multilayered and hybrid composite configurations, and to identify the key mechanisms responsible for increasing ballistic resistance while reducing areal density. The article synthesises and critically evaluates findings published in the available scientific literature focused on metallic, ceramic, polymeric, and hybrid armour systems. Particular attention is paid to mechanisms of energy absorption, projectile fragmentation, stress redistribution, and interactions between individual layers under dynamic loading. The analysis of published studies indicates that multilayer composite armour systems achieve higher ballistic efficiency than homogeneous systems due to the synergistic action of several protective mechanisms. Ceramic layers provide projectile destabilisation and fragmentation, while metallic and polymeric backing layers effectively absorb the residual energy and capture the resulting fragments. The findings also highlight the importance of armour architecture, the sequence of individual layers, and the quality of interfaces between materials, all of which significantly affect the resulting ballistic resistance, multi-hit capability, and the ratio between the level of protection and system weight. Current trends in armour technology development are directed towards the optimisation of multilayer configurations, the use of hybrid materials, bio-inspired architectures, graded structures, and advanced manufacturing technologies. The objective is to develop lightweight multifunctional armour systems that provide a high level of protection without a significant increase in areal density.