Engineering Physics Annotation << Back Enhancing the Efficiency of Laser Welding of Thick-Walled Steels and Aluminum Alloys Through Hybrid Technologies and Vacuum Application Ionina A.V., Budovskikh E.A. The article presents an analysis of modern industrial laser processing technologies using high-power fi ber lasers. The features of laser welding of thick metals (over 10 mm) are examined. It is shown that the use of narrow-gap edge preparation and multi-pass laser welding enables penetration depths of up to 40 mm while reducing heat input compared to arc methods. Special attention is paid to a comparative analysis of the efficiency of hybrid laser-arc welding and vacuum laser welding. It has been established that the hybrid process provides an increase in penetration depth by a factor of 1.3–2.0 compared to laser welding of the same power, and the use of inductive preheating can reduce the hardness of the heataffected zone from 430 HV to 350 HV and completely eliminate cold cracks. It is shown that vacuum laser welding (pressure 0.1 kPa) provides single-pass penetration of stainless steel up to 73 mm thick, which is comparable to electron beam welding, but does not require high vacuum (100 Pa is sufficient) and is not sensitive to residual magnetization of the parts. The technological features of welding aluminum alloys, including the problem of porosity and hot cracking, are considered. It is shown that the application of ultrasonic vibrations at a frequency of 40–80 kHz during laser welding promotes grain refinement from 50–60 μm to 15–20 μm and increases the joint strength to 100 % of the base metal strength. Practical recommendations are developed for selecting welding modes and surface preparation methods for various classes of materials. Keywords: fiber lasers, thick-section laser welding, hybrid laser-arc welding, vacuum laser welding, aluminum alloys, ultrasound, induction preheating, intermetallic layers. DOI: 10.25791/infizik.7.2026.1566 Pp. 30-39.