LCA Analysis of Forged Steel Production: Product Assessment and Optimization Strategies for Improved Environmental Performance

The European Green Deal and the Fit for 55 legislative package aim to reduce greenhouse gas emissions across the European Union and achieve climate neutrality by 2050. In this context, the LIGHTFORGE project aims to develop low-density Fe-Mn-Al-C steels suitable for industrial forging to reduce the weight of vehicles. This study assesses the environmental impacts associated with the production of a forged component (drop arm) manufactured from conventional 42CrMo4 steel, using the life cycle assessment methodology. A cradle-to-gate system boundary was used, with a functional unit of 1 ton of finished product. The data used in the study includes primary information provided by the companies involved in the project and secondary data sets from database such as Ecoinvent. The assessment was carried out using SimaPro software and the ReCiPe impact assessment method. The results show that over 60% of the impacts in the categories analyzed come from billet production processes. For this first part of the process, the steelmaking phase is the most critical due to the use of raw materials such as ferromanganese, ferromolybdenum, ferrochromium, and silicon. Hot rolling has been identified as the main critical phase for the categories of water consumption, fossil resource scarcity, and ionizing radiation. The environmental impacts associated with forging the drop arm are principally caused by the consumption of electricity. A sensitivity analysis examined two scenarios: replacement of the Spanish electricity mix with photovoltaic energy and changing from road to rail transport for billets. Increasing the share of renewable electricity leads to significant reductions in several impact categories, while shifting transport modes produces relatively minor benefits. The study identifies billet production, particularly the steelmaking phase, as the main critical point and suggests optimizing the use and sourcing of materials and the use of renewable electricity to reduce environmental impact. Future work will compare these results with drop arm manufactured from low-density Fe-Mn-Al-C steels and extend the assessment to include the use and end of life phases.