Abstract: Mining chains, as critical load-bearing components in coal mines, are prone to failure under long-term service in highly corrosive and humid environments, posing significant safety risks. To investigate their service failure mechanisms, this study examines two body-centered cubic structured mining chain steels through slow strain rate tensile testing (SSRT) conducted in a simulated coal mine environment with a pH of 7.6. The corrosion and hydrogen embrittlement (HE) characteristics are analysed, supplemented by electrochemical measurements and thermal desorption spectroscopy, to elucidate the underlying performance degradation mechanisms. The results indicate that after 21 days of immersion in a simulated environment, a dense Fe₃O₄ oxide film formed on the surface of the chain steel. SSRT tests revealed that the HE susceptibility of 51# was significantly higher than 21#, with fractures exhibiting typical characteristics of hydrogen-induced cleavage and intergranular fracture. The key factor influencing hydrogen-induced brittle fracture is the diffusible hydrogen content rather than its source. Hydrogen permeation during the initial corrosion stage reduces the grain boundary binding energy. Under tensile load, hydrogen atoms preferentially accumulate in stress concentration zones and defects, weakening atomic bonding, ultimately leading to hydrogen-induced fracture.

Key words: Hydrogen embrittlement, Coal mine corrosion environment, Hydrogen-induced delayed fracture, Slow strain rate tensile test