Effects of nitrogen on microstructure and mechanical properties of lamellar graphite iron

In various literature, there are many sources discussing the negative effects of nitrogen, especially on lamellar graphite iron. If there is a high concentration of nitrogen in the liquid metal, the most common problems encountered by foundry workers are defects related to nitrogen gas that occur on the surface and subsurface. Therefore, it is important to control nitrogen levels in the foundry. However, despite all the negative effects of nitrogen, with the correct concentration in liquid metal, nitrogen can increase the strength of the lamellar graphite iron, thus enabling design engineers to manufacture more durable machines or decrease wall thicknesses of casting parts. In this study, the effects of nitrogen on the strength and microstructure of lamellar graphite iron, its solubility, and interactions with other elements in the liquid metal bath were investigated. As a result of this study, supported by experiments, the practice of adding nitrogen to the liquid metal has been clarified in terms of when and how much to add. © 2023 Institute of Cast Metals Engineers. All rights reserved.