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The experimental studies of the effect of preliminary laser pulsed surface treatment on mechanical properties of the diffusion welding joints of Fe-Ni alloy were carried out. The alloy surfaces was treated in inert gas (Ar) environment by scanning beam of nanosecond laser pulses with a wavelength 355 nm, repetition rate 100 Hz and scanning speed 1 mm/s. Laser spot was 220 µm, the energy density 2 and 3 J/cm2. Treated samples as well as the control untreated ones were placed at the same container and were diffusion bonded by hot isostatic pressing (HIP) at the temperatures of 1000 and 1160°С. Ultimate strength and elongation of weld joint materials were determined by tensile testing. It is shown that laser pulse treatment leads to improvement both the ultimate strength and relative elongation of the weld joints. Mechanical properties of the weld joints depends on the laser energy density. Weld joint properties can be increased by optimization of the laser treatment parameters. The best results were achieved at laser energy density 2 J/cm2. Ultimate strength was increased by 12% and 29% for HIP temperatures 1160 and 1000°С respectively. The elongation values also increased from 42% for non-treated samples up to 51% for samples treated at 2 J/cm2 energy density. Preliminary laser treatment of welded surfaces permits to reduce the HIP temperature by 160°С and thereby reduce power consumption during HIP process.

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Specific features of the influence of laser processing applied to surfaces of 12Cr18Ni10Ti stainless steel samples on formation of bonding by the diffusion welding are considered.  The laser fluency was 2.1; 3.2 and 4.3 J/sm2, the diameter of spot was 220 µm. The beam scanning was carried out both in one direction and in two perpendicular directions. As a result of the laser processing with different mode parameters, there on their surfaces are formed microroughnesses of different heights. The researches demonstrated that the size of these microroughnesses is the main factor having an influence on the strength of welded joints. It agrees well with the data of experiments carried out earlier. The preliminary laser treatment of welding surfaces before diffusion welding brings a possibility to lower the temperature of a diffusion bonding process.