Simulation on scrap melting behavior and carbon diffusion under natural convection

Abstract

A 3D model applying temperature- and carbon concentration- dependent material properties was developed to describe the scrap melting behavior and carbon diffusion under natural convection. Simulated results agreed reasonably well with experimental ones. Scrap melting was subdivided into four stages: formation of a solidified layer, rapid melting of the solidified layer, carburization, and carburization + normal melting. The carburization stage could not be ignored at low temperature because the carburization time for the sample investigated was 214 s at 1573 K compared to 12 s at 1723 K. The thickness of the boundary layer with significant concentration difference at 1573 K increased from 130 µm at 5 s to 140 µm at 60 s. The maximum velocity caused by natural convection decreased from 0.029 m·s⁻¹ at 5 s to 0.009 m·s⁻¹ at 634 s because the differences in temperature and density between the molten metal and scrap decreased with time.

Keywords

scrap melting / natural convection / carbon diffusion / numerical simulation / electron probe micro-analyzer

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