CONTINUOUS HEAT TREATMENT FURNACE AND UTILIZING THE SAME, METAL PIPE AND METHOD OF HEAT TREATMENT

摘要

A continuous heat treatment furnace adapted to introduce an ambient gas into heating chamber (1) having heating zone (1a), continuously charge metal pipes along an axial direction from furnace entrance (2a) and discharge the metal pipes having undergone heat treatment from furnace exit (2b), wherein anterior compartment (4) having preheating zone (3) is disposed on the entry side of the heating chamber and wherein seal curtains (5a,5b) are disposed on the entry side and exit side of the anterior compartment. Further, there is provided a metal pipe heat treated by this heat treatment furnace and provided a method of heat treatment conducted with the use of the heat treatment furnace. It is preferred that posterior compartment (6) be installed on the exit side of the heating chamber and that seal curtain (7a) be fitted on the entry side of the posterior compartment. By virtue of these heat treatment furnace and method of heat treatment, even when the cleaning operation after cold working consists only of alkali defatting and washing, attachments to the internal and external surfaces of metal pipes can be easily removed prior to the heat treatment.