| Abstrakt: |
The paper presents an analysis of the serial production technology of the intake valve for high-speed marine diesel engines with dimensions 16/17 and 18/20. The task of increasing efficiency, power and reducing fuel consumption in marine diesel engines is urgent and has various design and technological solutions. One of the trends is the use of composite materials or a combination of intermetallic alloys, which provide higher performance properties. The results of studying the dynamics of fracture, chemical composition, hardness, macro-and microstructure of parts after full-scale bench tests are presented. The influence of the production technology and the chemical composition of the valve material on its operational characteristics is considered, the optimal values of the time and power of heating in the process of surfacing with high-frequency currents are obtained empirically. The relationship between the technological modes of surfacing and the microstructure of the bimetallic joint "heat-resistant steel+heat-resistant chromium-nickel alloy", as well as the microstructure and hardness of the cladding layer is revealed. It is proved that when the billet metal overheats during surfacing, the base metal dissolves in the deposited metal with the release of tungsten and excess iron content in the deposited layer, the latter leading to a decrease in the hot hardness of the nickel-based surfacing. Based on the studies carried out, the minimum requirements for ensuring the standard service life of the inlet valve in terms of the grain size of the base metal, the hardness of the working surface, the microstructure and the phase composition of the deposited layer are formulated. [ABSTRACT FROM AUTHOR] |
