Heat treatment method for long material, manufacturing method for long material, and heat treatment furnace used in above methods

Abstract

Provided is a method for heat treating longer-length products, in which a cylindrical batch-type heat treatment furnace with opposite ends thereof being enclosed and with the inner space thereof being divided into a plurality of heating zones along a longitudinal direction is used, and a longer-length product to be heat treated is heat treated, wherein the heat treatment furnace is configured so that, endmost heating zones each is divided into a plurality of divisions each having a length shorter than that of each of heating zones other than the endmost heating zones; and a heat source is disposed in each of divisions and other heating zones, and the heat treating method includes a series of steps of: (Step 1) in advance, determining the heating output pattern of each heat source in each division of endmost heating zones based on the measurement result of actual temperature in the end portion of the product to be heat treated at the time of heating and (Step 2) controlling the heating output of individual heat source, at the time of heat treatment for the product to be heat treated, based on the heating output pattern of each heat source determined in step 1 and further the measurement result of in-furnace temperatures of each division of endmost heating zones and each of other heating zones. By using this heat treating method, even in the heat treatment furnace having no heat source on both end walls thereof, the product to be heat treated can be heated uniformly throughout the overall length of the product to be heat treated with high accuracy.

Description

technical field [0001] The present invention relates to a heat treatment method of a long material capable of heat treating a longer material than before, a method of manufacturing a long material using the heat treatment method, and a heat treatment furnace used for carrying out the heat treatment method and the production method. [0002] Unless otherwise stated, the terms used in this specification are defined as follows. [0003] "Long material" refers to: small-diameter and long metal pipes, steel bars and other long materials. [0004] "Effective furnace length" refers to the furnace length corresponding to the maximum length of the material to be heat-treated that can be heat-treated at a uniform temperature in a heat-treatment furnace. [0005] "Inclined heating" refers to: when using a long cylindrical batch heat treatment furnace with closed ends to heat the material to be heat treated, the heat treatment furnace is divided into multiple heating zones in the length ...

AI Technical Summary

Problems solved by technology

Vacuum furnaces are designed to deal with the following problems: the radiant heat generated by a dedicated heater heats up the processed product, and it is difficult to heat the processed product uniformly because there is basically no convective heating, so quality defects may occur due to this uneven heating

However, as mentioned figure 1 As shown, for a heat treatment furnace in which heat sources are provided on the peripheral wall corresponding to each heating zone, and heat sources are not provided on both ends of the wall, since the end of the strip material has a significant temperature drop compared to the center, it is used as a long strip material. It is not ideal for the method of uniforming the treatment temperature of the heat-treated material that is as long as the material

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