Study on initial corrosion behavior of bogie steels with ferrite + pearlite and granular bainite structures immersed in sulfur-containing environment

Abstract

The corrosion behavior of bogie steel with two different structures immersed in a sulfur-containing environment for 12 h was studied, including ferrite + pearlite structure (the heating temperature is 1473 K, the final rolling temperature is 1123 K, the final cooling temperature is 873 K, and the cooling rate is controlled at 7–9 K/s) and granular bainite structure (the heating temperature is 1223 K, keep warm for 2 h, cooling in water is 10 min, the cooling rate is greater than 100 K/s). The results show that there is no significant difference in the initial corrosion rate between ferrite + pearlite and granular bainite structures. The former is affected by the micro-region galvanic effect and local residual stress to jointly promote corrosion initiation, while the latter has a uniform distribution of local residual stress on the surface, which is the main factor for corrosion initiation. After the sample is immersed, a dense thin rust layer quickly forms on the surface, blocking O2 in the solution, resulting in the dissolution of the ferrite matrix of the two structures is mainly affected by the reduction of H+ and SO32−/SO42−.

Keywords

• Bogie steel
• Initial corrosion
• Microstructure
• Surface rust layer characteristic
• Micro-galvanic effect
• S-containing environment