Research Article

From the microstructure of steels to the explosion of sparks

¹ Ecole polytechnique, Route de Saclay, 91120 Palaiseau, France
² LadHyX, UMR 7646 du CNRS, Ecole polytechnique, 91128 Palaiseau Cedex, France

^* e-mail: anthony.guillen@polytechnique.edu

Received: 13 July 2018
Accepted: 2 January 2019

Abstract

Sparks ejected by the grinding of steel can be observed to split in mid-flight. In this paper, we investigate the link between steel microstructure and the splitting behavior using two different steels: hypoeutectoid (containing less than 0:8% carbon) and hypereutectoid (>0:8% carbon). We used a high-speed camera filming at 1000 fps to observe the sparks, and a Scanning Electron Microscope to image the microstructures. For the hypoeutectoid steel, we also quantified the splitting behavior of the sparks by measuring the statistical distribution of the linear distance they travel before splitting occurs. We find that our results are coherent with the common explanation of the splitting phenomenon, stating that sparks split because their microstructures allow the formation of pockets of CO₂ by oxidation of Fe₃C, producing an internal pressure and leading to explosion.