Estimation of CO₂ Emission during Thermo-mechanical Process and Eco-steel Design of a Mn-Si-C Steel by Microstructural Control

Abstract

The amounts of CO₂ emission in the production of several commercial JIS standard steels have been estimated by the MLCA database prepared by Halada et al. Although low alloyed steels show smaller amounts of CO₂ emission from their database, the database can not estimate the influence of thermo-mechanical process. Therefore, the change of CO₂ emission during thermo-mechanical process has been estimated by the annual data concerning consumption of energies and materials publicized from Japanese steel makers. As a result, the change of CO₂ emission related to thermo-mechanical process was estimated to share from 5.1% (minimum) to 7.7% (maximum) of the total amount for production. This change is not negligible but much smaller compared with the influence of increasing the content of alloying elements. By combining the prediction of tensile properties of multi-microstructure steels based on micromechanics and the MLCA database, the Mn-Si-C steels are recommended as a candidate of eco-steels from the viewpoints of excellent tensile properties and low CO₂ emission for production.