Low-pressure vacuum carburizing process

Abstract

The invention discloses a low-pressure vacuum carburizing process. The low-pressure vacuum carburizing process comprises a temperature rising stage, a carburizing stage, a diffusing stage and a precooling stage. The temperature rising stage comprises the steps that a workpiece is vacuumized, and the vacuum degree is controlled within 1 Pa-20 Pa; and after vacuumizing is completed, heating is started, and the carburizing temperature ranges from 800 DEG C to 1050 DEG C. The carburizing stage comprises the steps that after the temperature of the workpiece reaches the set temperature of the process, acetylene gas is introduced into a furnace to maintain the carburizing gas partial pressure, which is named as a carburizing gas inflation pulse stage; after the carburizing gas inflation pulse stage is kept for a set time, vacuumizing is started, a certain time is kept under vacuum, which is named as a vacuumizing diffusion stage, and the carburizing gas inflation pulse stage and the vacuumizing diffusion stage are combined to serve as a carburizing pulse period; the whole carburizing stage is composed of a plurality of carburizing pulse periods; and when the carburized layer depth reaches the carburized layer depth set by the process, the carburizing pulse is stopped. The low-pressure vacuum carburizing process can effectively control the surface carbon content and the carburized layer depth of the workpiece, and the optimal carburizing effect of the workpiece is achieved.

Description

technical field [0001] The invention relates to the technical field of vacuum heat treatment, in particular to a low-pressure vacuum carburizing process. Background technique [0002] Carburizing is one of the important heat treatment methods. There are many types of carburizing processes, and the main types commonly used can be divided into: solid carburizing, liquid carburizing, atmosphere carburizing and special carburizing. Solid carburizing is carried out in a solid medium. The workpiece is buried in an iron box containing granular carburizing agent or coated with a layer of carburizing paste on the surface of the workpiece, and then placed in a furnace to heat and carburize; liquid carburizing is to carburize the workpiece Directly put into the salt solution that can decompose active carbon atoms to heat carburizing. In recent years, non-toxic liquid carburizing without cyanide salt has been popularized and developed, which has given new vitality to this carburizing p...

AI Technical Summary

Problems solved by technology

However, the mathematical model of carbon transfer is immature, the atmosphere in the furnace is difficult to monitor and control, the control accuracy of the carburizing process is not high, carbon black and tar are easily formed in the furnace, and the high cost caused by high requirements for equipment manufacturing and process materials, still to be studied and resolved

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