Amid escalating global climate crises and the urgent imperative to meet the Paris Agreement’s carbon neutrality targets, the steel industry—a leading contributor to global greenhouse gas emissions—confronts unprecedented challenges in driving sustainable industrial transformation through innovative low-carbon steelmaking technologies. This paper examines decarbonization technologies across three stages (source, process, and end-of-pipe) for two dominant steel production routes: the long process (BF-BOF) and the short process (EAF). For the BF-BOF route, carbon reduction at the source stage is achieved through high-proportion pellet charging in the blast furnace and high scrap ratio utilization; at the process stage, carbon control is optimized via bottom-blowing O₂-CO₂-CaO composite injection in the converter; and at the end-of-pipe stage, CO₂ recycling and carbon capture are employed to achieve deep decarbonization. In contrast, the EAF route establishes a low-carbon production system by relying on green and efficient electric arc furnaces and hydrogen-based shaft furnaces. At the source stage, energy consumption is reduced through the use of green electricity and advanced equipment; during the process stage, precision smelting is realized through intelligent control systems; and at the end-of-pipe stage, a closed-loop is achieved by combining cascade waste heat recovery and steel slag resource utilization. Across both process routes, hydrogen-based direct reduction and green power-driven EAF technology demonstrate significant emission reduction potential, providing key technical support for the low-carbon transformation of the steel industry. Comparative analysis of industrial applications reveals varying emission reduction efficiencies, economic viability, and implementation challenges across different technical pathways. The study concludes that deep decarbonization of the steel industry requires coordinated policy incentives, technological innovation, and industrial chain collaboration. Accelerating large-scale adoption of low-carbon metallurgical technologies through these synergistic efforts will drive the global steel sector toward sustainable development goals. This study provides a systematic evaluation of current low-carbon steelmaking technologies and outlines practical implementation strategies, contributing to the industry’s decarbonization efforts.

Based on the minimum degree of disregistry mechanism in oxide metallurgy, laboratory and industrial research have been conducted on intragranular acicular ferrite (IAF) induced by microalloying elements in austenite. Based on the chemical compositions of DH36 steel and Mg, Al, Ti, V, Nb microalloyed steel, experimental results show that in ingots' organization, both V and Nb can induce IAF, but when the adding sequence was Al-Mg-Ti, smaller and dispersion inclusions were formed in austenite. When the Mg content was 0.005 wt%, the inclusion structure induced IAF in austenite is as follows: MgO and Al₂O₃ forms the core and TixOy adheres to the Al-Mg complex inclusions to produce smaller particle size and dispersions of Al, Mg, Ti complex inclusions. Finally, upon lowering the temperature, carbonitrides of Ti, V, and Nb were precipitated on the outermost layer of the inclusions. These carbonitrides with small disregistry contribute to induce intragranular acicular ferrite.

The effect of Mg treatment on the microstructure and toughness of the heat-affected zone (HAZ) of shipbuilding steel after high-heat-input welding was investigated via laboratory and industrial testing. The welding process and Charpy impact tests were also carried out to evaluate the HAZ toughness of steel plates. First, typical inclusion characteristics were characterised with an ASPEX PSEM Explorer. Then, confocal laser scanning microscopy (CLSM) was used to observe the diameters of austenite grains under different holding times. The results showed that when the addition of microalloy elements were in the order of Al–Mg–Ti, this had an effect on dispersing inclusions, the largest proportion of which were micro-inclusions that had a particle size range of 1.0–1.5 μm. This accounted for 25.4% of the total inclusions, which was the highest amount. The micro inclusion particle size that was mainly distributed in the range of 0.5–3.5 μm accounted for 82.8% of all the micro-inclusions. The inclusion structure induced intragranular acicular ferrite (IAF) in austenite as follows: MgO and Al₂O₃ formed the core and Ti₂O₃ adhered to the Al–Mg complex inclusions to produce smaller particle sizes and dispersions of Al, Mg, and Ti complex inclusions. The 40-mm-thick plate obtained in the industrial test after welding had an average impact absorbed energy 2 mm from the weld joint in the heat-affected zone of 198.9 J at −20 °C, while the welding heat input was 150 kJ/cm, compared with the parent material’s low-temperature performance, which exceeded 88%.

Amid escalating global climate crises and the urgent imperative to meet the Paris Agreement’s carbon neutrality targets, the steel industry—a leading contributor to global greenhouse gas emissions—confronts unprecedented challenges in driving sustainable industrial transformation through innovative low-carbon steelmaking technologies. This paper examines decarbonization technologies across three stages (source, process, and end-of-pipe) for two dominant steel production routes: the long process (BF-BOF) and the short process (EAF). For the BF-BOF route, source-stage decarbonization employs high-proportion pelletized ore charging and elevated scrap ratios. The process stage integrates converter bottom-blowing with O2-CO2-CaO composite injection technology for optimized carbon control. The end-of-pipe treatment combines CO2 recycling with carbon capture, utilization, and storage (CCUS) for deep decarbonization. The EAF route establishes a low-carbon production system through green high-efficiency electric arc furnaces and hydrogen-based shaft furnace processes. Source-stage improvements utilize green electricity and advanced equipment for energy efficiency. Process optimization implements intelligent control systems for precise smelting, while end-of-pipe solutions incorporate waste heat recovery and slag resource utilization to form closed-loop operations. Hydrogen direct reduction ironmaking and green electricity-driven EAF technologies demonstrate significant emission reduction potential, providing crucial technological support for industrial decarbonization. Comparative analysis of industrial applications reveals varying emission reduction efficiencies, economic viability, and implementation challenges across different technical pathways. The study concludes that deep decarbonization of the steel industry requires coordinated policy incentives, technological innovation, and industrial chain collaboration. Accelerating large-scale adoption of low-carbon metallurgical technologies through these synergistic efforts will drive the global steel sector toward sustainable development goals. This research systematically evaluates current low-carbon steelmaking technologies and proposes implementation strategies, offering valuable insights for the industry's green transition—a cornerstone for building a sustainable future.