Abstract: High temperature steam oxidation behavior of the P92 and G115 steel with and without shot peening was studied by using a high temperature steam oxidation test device. The results show that, the steam oxidation kinetic curves of the three specimens conform to the law of ΔW=ktⁿ at 650 ℃. The oxidation mass gain of the G115 steel is much smaller than that of the P92 steel under the same steam oxidation time, mainly because of the formation of rich Cr layer in the steel and the precipitation of rich Cu phase at the interface of the oxidized layer. G115 steel treated by shot peening has less oxidation mass gain than G115 steel without shot peening. The surface of G115 steel after shot peening produces a large amount of plastic deformation, which leads to the introduction of high-density dislocation and slip bands. Martensite lath of the inner wall breaks down, which leads to the increase of martensite lath boundary. The massive increase of slip bands, dislocations and martensite lath boundaries provides diffusion channels of Cr elements to the surface, which accelerates the diffusion rate of Cr elements in the matrix to the surface, and becomes the main reason for improvement of anti-vapor oxidation performance.

Key words: high-temperature steam oxidation, shot peening, martensitic heat-resistant steel, oxidized layer