Insights into the characteristics of corrosion products formed on the contact and exposed regions of C1045 steel bolt and nut fasteners exposed to aqueous chloride environments

•Corrosion products on different regions of C1045 bolt are characterized for the first time.•Differential aeration/concentration effects induced heterogeneity in the corrosion products.•Reactive phases, γ-FeOOH and β-FeOOH dominated at the exposed and contact region, respectively.•Magnetite, Fe3O4 was detected in both regions under low oxygen conditions.•Due to the low amount of α-FeOOH, the rusts in both regions lack stability and protectiveness.