In most cases, the hexagonal pier is pulled to the heat treatment plant after rolling. In a few cases, the hexagonal pier is pulled to the heat treatment plant without rolling, but it is only limited to grade 8.8. After heat treatment, the hardness of 10.9 and 12.9 is high, and rolling is laborious.

Heat treatment: cleaning (some manufacturers don't clean it, and the disadvantage of not cleaning is that the oil of the bolt itself is not fully burned in the quenching process to form carbon black, which pollutes the quenching oil)-mesh belt furnace quenching (methanol atmosphere protection)-cleaning-tempering (tempering can be divided into various situations, one is air cooling and the other is water cooling, and tempering is not needed for high-strength bolts containing chromium.