Rolling mill rolled profiles, part of which can be directly used as finished products, and a part of the need for heat treatment, such as annealing, quenching, tempering, normalizing (normalization), tempering treatment, carburizing, nitriding, cyanide and so on in order to be good as a finished product. Due to the different composition and use of materials, the heat treatment process is also different, and the requirements for heat treatment equipment are also different.

1、Classification of heat treatment furnace heating equipment

    Heat treatment furnace heating equipment has two categories, one is direct heating, such as direct electric heating, high-frequency induction heating, etc.; a class of indirect heating, a variety of heat treatment furnace belongs to this category. This heat treatment furnace is categorized as follows:

1.1 Hearth furnace: according to the heat system library is divided into batch furnace and continuous furnace.

1.1.1 Intermittent furnace: according to the furnace can be divided into box furnace, trolley furnace, hood type furnace, pit type furnace, pit type furnace.

1.1.2 continuous furnace: according to the form of conveyor can be divided into pusher-type furnace, chain furnace, roller-type furnace, step furnace, ring furnace, chamber furnace, shock bottom furnace, tunnel furnace, horizontal traction furnace, tower furnace.

1.2 Bath furnaces: divided into externally heated and internally heated. The externally heated type is divided into electric heating and fuel heating; the endothermic type is divided into tubular and electrode type.

1.3 Flow ionization furnace: can be divided into electrode type, electric heaters and gas type.

1.4 Vacuum furnace

1.5 Atmosphere protection furnace

2、Characteristics of Heat Treatment Furnaces

  Heat treatment due to different process requirements, the temperature is high up to 1300 ℃, low only about 100 ℃ furnace temperature higher than 650 ℃, the transfer of heat to the radiation mode, supplemented by convection; furnace temperature is lower than 650 ℃, the transfer of heat mainly rely on convection mode. Heat treatment requires a uniform temperature of the furnace chamber to avoid the Lubu temperature is too high. The temperature difference of heat treatment is so big that the mechanism of its furnace is also very different.

2.2 The temperature control of the heat treatment furnace is relatively strict.

    Heat treatment furnace can ensure that the temperature required by the heat treatment process, the product quality and a great impact, generally up and down not more than 3 ~ 10 ℃. The temperature distribution on the section of the heated object should be as uniform as possible, the temperature difference shall not exceed 5 ~ 15 ℃. In terms of controlling furnace temperature, electric furnace is superior. In order to achieve the purpose of accurate temperature control, it is best to uniformly do not know the burner, so that it is easy to control the segments, the burner is too little, too centralized, prone to local overheating. At the same time, the arrangement of the burner or electric heaters and furnace structure should be conducive to the furnace gas circulation.

2.3 Heat treatment furnaces should minimize oxidation and decarburization of the metal.

Heat treatment of just now, do not allow surface oxidation and decarburization, should maintain the surface finish. Heat treatment furnaces often need to be sealed in order to control the composition of the furnace gas, and sometimes bar to maintain a particular atmosphere in the furnace chamber.

2.4 Low productivity and thermal efficiency of heat treatment furnaces.

    Heat treatment, in order to make the temperature uniform on the metal section, so that the crystalline organization of the transformation is complete, the need to make the metal in the furnace to stay for a long time, regardless of which heat treatment,, the material in the furnace have one or more heat or insulation stage, the cooling process is also often carried out in the furnace. Some varieties of heat treatment, and even several heating, holding and cooling. Many heat treatment furnaces are cycle operation, so the productivity of the heat treatment furnace is much lower than the rolling and forging heating furnace.