As a fundamental raw material industry in the industrial sector, the steel industry is the largest emitter of carbon among the 31 manufacturing sub-sectors. Assessing the sustainability level of the steel industry is thus of critical importance for advancing carbon reduction efforts. In 2024, crude steel production in Belt and Road Initiative countries reached 1.43 billion tons, accounting for 75.8% of global output. However, significant disparities exist in the development of steel industries across these countries, necessitating the construction of a robust model to evaluate their relative sustainability. This study proposes an ESG-MI evaluation model that integrates environmental, social, governance, resource, and industrial dimensions, and applies it to panel data from 64 BRI countries between 2000 and 2023 to assess the sustainability level of their steel industries. Furthermore, an obstacle degree model is employed to identify key hindering factors. The study yields the following key findings: (1) From 2000 to 2023, the sustainability level of the steel industry along the BRI showed a steady upward trend, with an average annual growth rate of 1.04%. (2) Industrial development and governance are the main drivers of sustainable development in the steel sector, while environmental performance remains a major weakness. Additionally, the resource supply chains in BRI countries are fragile and vulnerable to external shocks. (3) The sustainable development of the steel industry along the BRI follows a geographical transmission pattern of “Europe → East Asia → Middle East → Southeast Asia → South Asia.” (4) Based on obstacle degree analysis, industrial value added (X20), crude steel output per capita (X11), and the proportion of ores and metals in total exports (X12) are identified as the top three obstacles to sustainable development in the steel industry, with significantly greater hindering effects than other indicators.

This study aims to clarify the intrinsic relationship among the establishment of FTZs, industrial agglomeration, the digital economy, and green technological innovation. This paper empirically examines the impact of the establishment of FTZs on regional GTI and its mechanisms, based on panel data from 285 cities between 2009 and 2022, using the DID method. The findings show that the establishment of FTZs significantly enhances the level of GTI in the cities where they are located, with the GTI index increasing by an average of 696.501 units. Regional analysis reveals that coastal FTZs have a significantly stronger positive effect on GTI than inland and border FTZs. Furthermore, the promotion of GTI by FTZs intensifies with rising per capita GDP. Mechanism analysis indicates that FTZs promote the development of green industries through industrial agglomeration and the digital economy, thereby further stimulating GTI. Based on these findings, this paper proposes four policy recommendations: (1) strengthen region-specific policies and develop strategies to support GTI tailored to regional characteristics; (2) promote industrial transformation and upgrading, encouraging the green transformation of traditional industries; (3) improve the policy support system and optimize incentives for GTI; (4) enhance the greening of the financial system to increase the marketization and internationalization of green financial products.