Structure studies of porous oxide layers formed on 13CrMo4-5 steels long-term operated in the power industry

The paper contains results of studies on the formation of oxide layers on 13CrMo4-5 steel long-term operated at an elevated temperature. The material studied comprised specimens of 13CrMo4-5 steel operated at the temperature of 455oC during 130,000 hours (steel 1) and 540oC during 120,000 hours (steel 2). The oxide layer was studied on a surface and a cross-section at the outer surface of the tube wall. The paper contains results of studies of porosity in the oxide layer. The oxide layer formed on the studied steel 1 is ~146 μm thick, while on the steel 2 ~248 μm. It has been found that steel 2 has higher porosity.