in the Manufacturing Technology of Pipeline Valve Castings
DOI:
https://doi.org/10.15276/opu.1.73.2026.10Keywords:
gray cast iron, pipeline valves, modification, leak-tightness, strength, microstructure, multi-factorial experimentAbstract
The operational reliability of liquid and gas transportation systems directly depends on the quality of pipeline valves. Traditional manufacturing technologies for gray cast iron castings of Grade 250 (SCh250) do not always ensure the stability of these characteristics, resulting in a significant percentage of rejects due to leakage or insufficient strength under peak loads. Therefore, searching for optimal methods of alloying and modifying cast iron is a critical task for modern foundry production. The study aims to improve the performance characteristics and reduce the scrap rate of pipeline valve castings by enhancing the technological processes for out-of-furnace melt treatment through the combined influence of alloying and modifying additives. The multi-factor experimental design method was employed in this work. To confirm the results, a comprehensive metallographic analysis of the cast iron structure was conducted. During the study, mathematical models in the form of regression equations were obtained, which adequately describe the dependence of strength and pressure tightness on additive concentrations. It was established that introducing a copper-phosphorus alloy promotes matrix pearlitization and the refinement of graphite inclusions, thereby improving casting density. The optimal range for component addition was determined. This enables stable strength values that exceed the requirements for gray cast iron Grade 250 (SCh250), while simultaneously reducing leakage-related rejects by 1.5…2 times. For the first time, the synergistic effect of the joint application of a copper-phosphorus alloy and a magnesium-containing modifier in thin-walled castings with complex configurations is quantitatively described. The influence of these elements on the formation of a dense structure capable of withstanding high hydraulic pressure without seepage of the working medium was proven. The research results were implemented in the manufacturing process for valve body parts, allowing for cost optimization of expensive additives and a significant increase in the yield of sound castings. The proposed technology is universal and can be adapted to produce other types of critical pressure-tight castings.
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