Features of hydrogen cracking process of heat-strengthened reinforcing steels

Abstract

The effect of heat treatment of reinforcing steels of St5, 18GS, 20GS, 23Kh2G2Ts, 30GST and 35GS grades on the change in their resistance to hydrogen cracking is considered. For St5 steel, it was found that an increase in the tempering temperature contributes to an increase in resistance to cracking by obtaining a highly plastic structure with an increased ability to relax internal microstresses. For 30GST and 35GS steels, optimal heat treatment modes are determined to ensure their resistance to hydrogen cracking. For 30GST steel, this mode is quenching from 900 °C with cooling in water + tempering with electrical heating at 500 °C, and for 35GS steel — triple heat treatment of the type of intercritical quenching from temperatures of 900/700 °C or 800/700 °C, followed by tempering at temperatures of 300 or 400 °C, respectively and heat treatment from 900 °C with double tempering (from 400 °C (furnace heating) and 500 °C (electrothermal hardening)). The features of the destruction process of reinforcing steels in an environment causing hydrogen cracking are considered. It is shown that the propagation of corrosion cracks has a mixed character (transcrystalline and intercrystallite).