Steel heat treatment method and system

Abstract

Different from an existing carburizing and quenching technology through which the area fraction of the martensite structure of the surface layer of a steel piece cannot be obviously improved, according to a steel heat treatment method and system, especially, a preheating device, a heating furnace, a quenching device, a hot pressing device, a tempering furnace and an air cooling pipe device form aninfrastructure of the steel heat treatment system. Through the preheating device and the heating furnace, continuous steel is heated to 800-980 DEG C, and the tempering and hardening effects on the continuous steel can be achieved. Meanwhile, quenching treatment is conducted on the tempered continuous steel through the quenching device (a lead hath furnace), and most of austenite in the continuous steel can be converted into martensite better. The continuous steel is flattened through the hot pressing device at first, and internal stress, generated due to the quenching procedure, of the continuous steel is eliminated. More especially, the temperature of the continuous steel is further lowered to 100 DEG C or below through an air cooling device, and accordingly, the area fraction of the martensite structure of the surface layer of the continuous steel can be remarkably increased.

Description

technical field [0001] The present invention relates to the technical field of heat treatment applied in metal processing, especially to a steel heat treatment method and system, which are used to perform continuous processing such as quenching and tempering, quenching, and tempering on a continuous steel, and then improve the continuous steel hardness. Background technique [0002] The carburizing process is used to process low carbon steel into high carbon steel. The specific method is to place the low-carbon steel workpiece into a heating environment with a carburizing medium (such as methane, ethane, etc.), and use high temperature to heat the low-carbon steel workpiece to make it austenitized (Austenite). ). It is worth noting that during the transformation of the surface layer of the low-carbon steel workpiece into an austenite structure, the carbon atoms decomposed by the carburizing medium will penetrate into the surface layer of the steel piece, increasing the car...

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Problems solved by technology

[0011] (1) Although the five process steps can shorten the process time of carburizing treatment, the carbon content of the steel part is limited to less than 0.6wt% instead, resulting in restrictions on the application of the semi-finished steel part to the finished product;

[0012] (2) Although the secondary quenching process can transform part of the bainite (Pearlite) into fine bainite (FinePearlite), it cannot significantly increase the area fraction of the martensite structure on the surface of the steel. The effect of improving the surface hardness of steel parts is limited

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