Abstract
Plasma arc is a powerful advanced tool used for pro-cessing of various materials. One of the main techniques used in material processing includes cutting. This article looks at an important issue of finding efficient plasma-arc cutting techniques for processing of the low alloy steel grade of 09G2S. This steel grade is widely used to make fabricated assemblies for various applications. The research helped identify the factors that directly affect the quality of the cut. A study has been carried out to determine the relationship between the plasma cutting technique applied and the structure and the properties of the heat affected zone and the microgeometry of the cut surface. It is shown that martensite with the hardness of 325 to 340 HV appears to be present in the metal of the heat affected zone at different plasma cutting conditions. At the same time there appears to be no impact on the structural composition within a wide range of process parameters. The current increase from 220 to 280А at a constant voltage resulted in a wider cut and produced a considerable impact on the microgeometry of the cut surface due to an intensified removal of the molten metal from the cutting channel. The surface roughness Ra of the cut may vary from 0.4661 to 2.7811 µm, with the waviness Rz varying from 2.9360 to 13.1519 µm. Based on the results obtained efficient plasma cutting techniques have been proposed for a 12 mm rolled material made from the low alloy steel grade of 09G2S, which can ensure the desired combination of properties. The use of efficient plasma cutting techniques enables to obtain cutting edges that are almost parallel and have minimum roughness thus minimizing the cost of downstream processing.
Keywords
Plasma cutting, low alloy steel, heat affected zone, cooling rate, tempering, martensite, microgeometry, roughness, waviness.
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