Issue 78

M. Bronovets et alii, Frattura ed Integrità Strutturale, 78 (2026) 367-377; DOI: 10.3221/IGF-ESIS.78.21

of emulating the actual operating conditions of bearing units. To create rolling conditions, assembled sets of steel balls made of 52100 steel (Russian equivalent ШХ 15) were used.

Element Content

C

Cr

Si

Mn

Ni

S

P

Fe

%

0.90 - 1.00 17.0 - 19.0 up to 0.80 up to 0.80 up to 0.60

up to 0.025

up to 0.030

balance

Table 1: AISI 440-C (Russian equivalent 95 Х 18 Ш ).

Figure 1: Bearing steel specimens.

The surface treatment of the samples was carried out using an original laser setup assembled at the Institute of Continuous Media Mechanics, Ural Branch, Russian Academy of Sciences. The setup incorporates a Nd:YAG high-energy laser Beamtech SGR-Extra-10 and an industrial robotic manipulator STEP SR50 (Fig. 2). The wavelength of laser radiation is 1064 nm, the maximum frequency of laser pulses is 5 Hz, and the energy of laser radiation varies from 1 to 9 J. The duration of laser pulses is 10 ns. A six-axis robotic manipulator with a payload capacity of 50 kg positions the part with an accuracy of up to 0.25 mm and a movement speed in the range from 0.1 mm/s to 500 mm/s. The sequence and trajectory of processing are set in specialized software based on a three-dimensional model of the part. The complex includes three optical systems. These components facilitate the focalization of the laser beam into squares with sides measuring 1 and 3 mm and a circle with a diameter of 2 mm, which provides variability in the energy density of the laser impact and the design of the placement of laser spots on the surface of the part depending on its geometry.

(A) (B) Figure 2: Laser shock peening setup (A) – Nd:YAG high energy laser Beamtech SGR-Extra-10; (B) – industrial robotic manipulator STEP SR50. In the context of this work, the choice of the LSP mode was determined by its optimality in terms of the energy density of the laser impact, which does not cause a secondary plasma torch [8] and is based on the authors’ previous works, in which processing modes were selected for plane geometry samples [9, 10]. LSP was performed using radiation with a round spot with a diameter of 2 mm. The treatment was performed in a single pass with a 30% overlap between adjacent spots. The laser pulse energy and frequency were 3 J and 5 Hz, respectively. The role of a transparent limiting layer was performed by water, continuously supplied to the processing zone and forming a stable laminar flow on the surface of the sample. The thickness of the water layer was approximately 0.5 mm. The laser fluence and scanning speed were set to 96 J/cm² and 7.8 mm/s, respectively. The treated area was approximately 1962 mm², and the processing time per specimen was about 250

370