DOI: https://dx.doi.org/10.24866/2227-6858/2019-3-10

Kuleshov I., Leontyev L.

IGOR KULESHOV, Surveyor of the Far East Branch Office of the Russian Maritime Register of Shipping, e-mail: kuleshov.ii@rs-class.org
29a. Stanyukovicha St., Vladivostok, Russia, 690003
LEV LEONTYEV, Doctor of Engineering Sciences, Professor, ORCID: 0000-0002-8072-306X; ResercherID: U-9351-2017, ScopusID: 6603944093, e-mail: leontyev.l.b@yandex.ru
Department of Welding Engineering, School of Engineering
Far Eastern Federal University
8 Sukhanova St., Vladivostok, Russia, 690091

Improvement of durability of piston crowns of the low speed marine diesel engines by technological methods

Abstract: The article is aimed to investigation of impact of laser treatment grey perlitic cast iron SCH25types with variable chemical composition on melting depth, roughness, structure and surface hardness. It was identified that at the heat input from 10.5 to 11.0 j·s/mm only melting of peaks tops with reduce of peaks height up to 4–8 mkm was observed, and the microstructure of the thermohardened area was – martensite. Laser treatment without melting of cast iron surface will increase wear resistance up to 4 times and reduce friction index by 1.8 times.
Increase of heat input over 20 j·s/mm leads to the cast iron melting and ledeburite forming. Due to heat input increase from 20 j·s/mm to 84 j·s/mm melting depth increases from 0.22 mm to 0.38 mm accordingly. Cast iron surface melting doesn’t improve its tribological properties.
Modification of hardned surface without melting by vermiculite-based material provides wear reisstance up to 1.5 time and friction index reduce at 15% in comparison with cast iron hardened by laser treatment only. Melting area modification provides increase of surface wear resistanse only to 12%, thus friction index reduces insignificantly.
To increase the durability of the piston crowns of the low-speed marine diesel engines, the authors proposed a technology for installing anti-wear cast iron rings hardened by laser treatment, followed by tribo-modification of their working surface with vermiculite-based layered silicate.
Keywords: durability, piston crown, piston grooves, diesel, tribotechnical material, cover, wear resistance.

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