STEEL PIPE QUENCHING METHOD

摘要

This quenching method water cools and quenches a steel pipe (1) from the outer surface and water cools at least one part other than the end parts of that pipe without water cooling the end parts of the pipe. Use of an embodiment that provides a part that is not directly water cooled around the entire perimeter in at least one part in the axial direction of a part other than the end part of the pipe, or an embodiment that repeatedly implements water cooling and stops a water cooling intermittently in at least one part of the quenching process, and further, an embodiment in which, in the water cooling of the outer surface of the steel pipe, strong water cooling is carried out with the temperature of the outer surface of the steel pipe in a temperature range higher than the Ms point. Thereafter, forced cooling of the outer surface is carried out switching to weak water cooling or air cooling, and cooling is carried out to below the Ms point are preferable. According to this quenching method, preferable use is for quenching processes for medium and high carbon content steel pipe (steel pipe of low alloy steel or medium alloy steel) or martensite stainless steel pipe.