Characterization of ultra-low carbon steel: A preliminary approach to investigate the quality and standards of locally-available steel

TL;DR

This study investigates the thermal, mechanical, and microstructural properties of ultra-low carbon steel, focusing on how etchant concentration and time affect its microstructure and revealing optimal etching conditions for quality assessment.

Contribution

It provides a preliminary characterization of locally-available ultra-low carbon steel, highlighting optimal etching parameters and microstructural features relevant for quality standards.

Findings

Optimal etchant composition is 8% nitric acid in ethanol.

Best microstructure clarity achieved at 90 seconds etching time.

Steel exhibits high ductility, malleability, and softness.

Abstract

In the present work, experimental study has been carried out to expose the thermal, mechanical, and microstructural properties of low carbon steel as well as to inspects the influence of etchant concentration and etching time on its microstructure. Ultra-low carbon steel, in the form of a sheet, was collected from the Mughal Steel Industry, Peshawar, Pakistan. The sample was chemically etched, using Nital as an etchant, by two different methods: first, by changing the etching time while keeping the composition of etchant the same and second, by keeping the time constant while varying the etchant composition in a range of 5-14 %. The microstructure analysis revealed that ultra-fine grain can be obtained for the etchant composition of 8 % nitric acid in ethanol. Additionally, we noticed that the best etching time, for getting a clear morphology, was 90 s. The X-ray diffraction revealed mainly alpha-iron. Thermal analysis showed a minor weight loss followed by weight gain of 1.31 wt %. Contraction and expansion, observed on the TDA curve, suggested the transformation of BCC to FCC structure. Our results indicated that the specimen is highly ductile, malleable and soft.