كنترل شكل آخال ها و تاثير آن بر خوردگي و خسارات هيدروژني فولاد از نوع API در محيطهاي شامل گاز H2S

Effect of Inclusion Shape Control on Corrosion and Hydrogen Damage in H2S Included Environment on API Steel

Recently steel producers have used several different methods to increase properties such as ductility, impact strength and formability. In this regards producing steel with very low amount of inclusion, very small size inclusion and modified inclusion can be mentioned. It should be considered, however, presence of inclusions in steel can have worse effects on corrosion properties and strength of hydrogen damage in H2S included environment. In this research, the API-X52 steel produced by Mobarekeh Steel Co. was used. The steel was melted in a 50kg, medium frequency induction furnace and deoxidation was performed using aluminum. The calcium was added outside of the furnace. The effect of using calcium barrier materials on the morphology control, distribution, amount and size of aluminum oxide inclusions was studied using scanning electron microscope and image analyzing computer program. Displacement of glycerin was used to measure the amount of diffusible hydrogen. Immersed test in sour media was performed on NACE standard and similar media with added thiosulphate ions. The results suggest that thiosulphate ions can be a suitable replacement for H2S gas, at least in research tests. The results also show that reducing and spherical inclusions lead to reducing diffusible hydrogen and corrosion rate.