Effect of RE on Microstructure and Mechanical Response of CO₂ Corrosion Resistant 1Cr Steel

In order to study the effect of rare earth(RE) on the mechanical response of the carbon dioxide corrosion resistant 1 Cr steel, the microstructures of the steels were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy, and then the mechanical properties of the material were tested by using a universal electronic testing machine and a Zwick/Roell HTM5020 testing machine for quasi-static and dynamic tensile, respectively.The results show that the addition of RE can reduce the cementite spacing of pearlite in the rolled microstructure, produce more precipitates and ultrafine pearlite in the quenched and tempered microstructure, and thus result in a decrease of strain hardening index and an increase of elongation. The Cowper-Symonds constitutive model is used for fitting the dynamic response of the materials, it is found that the addition of RE elevates the model parameters D and p values, which exhibit a negative correlation with the strain hardening index. The research has reference value for the design and material selection of pipe strings in the downhole service environment of oil and gas field.