Steels for pipes of furnaces for pyrolysis of gaseous hydrocarbons

Conclusions

• 1. The mechanical characteristics of Kh20N14S2 steel and the resistance to prolonged exposure at 700, 800, 850, 900, and 950\dgC are similar to those of Kh23N18 steel. The decrease in the concentration of carbon and the increase in the silicon concentration in Kh20N14S2 steel decreases the strength.

• 2. During prolonged heating at 700\2-950\dgC Kh20N14S2 steel undergoes structural transformations with formation of the \gs-phase, which decreases the impact strength and the ductility and somewhat increases the hardness.

  The impact strength of the aged steel is considerably higher at the aging temperature than at 20°C.

• 3. Kh20N14S2 steel with 2.2\2-3% Si has good resistance to carburization. The resistance to carburization increases with increasing concentrations of silicon in the steel. The resistance of Kh20N14S2 steel to scale formation is considerably higher than that of Kh23N18 steel.

• 4. Kh20N14S2 steel containing up to 0.12% C and 2.2\2-3% Si can be used for pipes in pyrolysis furnaces in place of Kh23N18 steel.