On the Effect of Hot Rolling on Inclusion Size and Distribution in a Cast AISI 1070 Steel Railroad Wheel


The goal of this work is to examine the effect of hot deformation on shrinkage porosity and nonmetallic inclusions in an AISI 1070 grade steel industrially produced wheel casting. Steel cleanliness is an important consideration as it influences the mechanical properties of the final product. A high density of porosity and inclusions have been shown to be detrimental for mechanical properties, especially during hot rolling. Using a laboratory-scale rolling mill, cast preforms were subjected to a 66% cumulative reduction to determine the effect of thermomechanical processing on void closure and inclusions that may produce anisotropy in mechanical properties. Quantitative automated feature analysis, AFA, of inclusion type, size, morphology, and distribution was conducted utilizing an Aspex PICA 1020 scanning electron microscope to determine differences in inclusions and shrinkage porosity in the as-cast and as-rolled conditions. The results were compared with previously reported impact toughness values which indicated a trend with MnS projected length and average impact toughness in the T-L orientation. Reduction in shrinkage porosity was also verified utilizing 3D micro-X-ray CT scans. The AFA results showed a decrease in shrinkage porosity from 177 ppm in the as-cast condition to less than 35 ppm after rolling. Pores were in general much smaller and widely distributed after hot rolling and this would suggest improved impact properties. Analysis of nonmetallic inclusions revealed three primary categories of inclusions that included MnS, Al2O3, and complex inclusions that mainly consisted of MnS with an Al2O3 core, with small quantities of mixed silicates of Mn and Al and calcium aluminates (CaAl2O4).


Materials Science and Engineering


This work was supported by the Amsted Rail Company and the Peaslee Steel Manufacturing Research Center (PSMRC) at Missouri S&T, and the authors would like to thank them for sponsorship and support for the Cast Pre-Form Forging project for which this publication is a part of.

Keywords and Phrases

Hypoeutectoid Steel; Impact Toughness; Inclusion Analysis; Micro-X-Ray CT Scans; Projected Length; SEM AFA; Void Closure

International Standard Serial Number (ISSN)

2163-3193; 1939-5981

Document Type

Article - Journal

Document Version


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Publication Date

01 Jan 2022