Effect of Nb and Ti on carbide precipitation and hydrogen embrittlement of V-containing 125ksi casing steel

In this study, Ti and Nb elements were further added to the 125 ksi grade oil casing steel containing V element to study the precipitation behavior of carbides and the change of hydrogen embrittlement sensitivity under the condition of composite precipitation. The carbide precipitation of Ti/V and Nb/V during the quenching and tempering process and its effect on the hydrogen embrittlement sensitivity of the stress rupture test ( SSRT) were studied by means of microstructure and properties analysis and hydrogen embrittlement sensitivity test. The results show that Ti/V can effectively refine the size of the precipitated phase, and Nb/V can reduce the dislocation density, reduce the proportion of high angle grain boundaries, and increase the proportion of ∑ 3 grain boundaries, thereby reducing the hydrogen embrittlement sensitivity of the material.