Analysis of the specific operating conditions of technical fleet vessels and the development of technologies for marine component restoration

Abstract

The article examines the specific operational conditions of the technical fleet, particularly dredging equipment, which is characterized by extreme working environments for bucket-chain mechanisms. The design features of bucket-chain pins, which are exposed to high contact pressures, abrasive wear, the corrosive action of seawater, and dynamic loads leading to intensive loss of serviceability, are analyzed. It is established that traditional restoration methods, including thermal spraying, are ineffective due to the high porosity of coatings and their insufficient ability to withstand localized loads. Based on research conducted at the Odessa National Maritime University, a technology for restoring bucket-chain pins using electric-arc surfacing with flux-cored wires of various chemical compositions is proposed. The properties of materials PP-AN 170, PP-AN 125, and PP-AN 122, as well as the features of weld-layer formation, hardness, structural characteristics, and technological limitations, are examined in detail. It is shown that the use of combined helical surfacing with a sub-layer of ductile SV-08A wire helps minimize crack formation and ensures uniformity of the deposited layer. Comparative wear-resistance tests carried out using a specialized experimental setup confirmed the functional effectiveness of the deposited materials. It is found that PP-AN 122 and PP-AN 170 wires provide similar levels of relative wear; however, PP-AN 122 demonstrates technological advantages due to better machinability after surfacing and increased hardness after heat treatment. It is shown that increasing the rotational speed and test duration results in stabilization of wear after the initial run-in stage. The study concludes that PP-AN 170 and PP-AN 122 flux-cored wires are suitable for restoring bucket-chain pins of dredgers, and identifies further directions for improving component service life through optimization of clearance fits and enhancement of machining processes.