Volume 6, Issue 2 (February 2009)
An Overview of Technology and Equipment for Hardening of Large Steel Parts
In the paper, multi-step accelerated-interrupted (AI) quenching is illustrated by its application to fittings for oil and gas pipelines with a diameter up to 1420 mm (1.42 m) and wall thickness from 16 to 80 mm. The multi-step AI quenching is used to improve the mechanical properties of steel parts on the basis of regularities of full film boiling. The developed technology is ecofriendly since it uses water instead of oil as a quenchant. The industrial conditions are described for an automated quench system where the quenchant was water at 60–90°C, which was circulated at different velocities. Favorable temperature differences along the thickness of the wall of parts to be quenched can be achieved by applying multi-step quenching. Software and hardware have been developed to govern the process.