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Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

What is vacuum heat treatment technology?

Vacuum annealing, normalizing, vacuum quenching, vacuum tempering, quenching and tempering.Do you clearly distinguish these vacuum heat treatments? The role of vacuum heat treatment is to improve the mechanical properties of materials, eliminate residual stress and improve the machinability of metals.

1.Vacuum heat treatment

The purpose of vacuum heat treatment is to improve processing performance, eliminate internal stress and prepare a good metallographic structure for vacuum heat treatment. Its vacuum heat treatment process includes vacuum annealing, normalizing, aging, quenching and tempering, etc.

1) Vacuum annealing and normalizing

Vacuum annealing and normalizing are used for hot-worked blanks. Carbon steel and alloy steel with a carbon content of more than 0.5% are often vacuum annealed in order to reduce their hardness and easy to cut; carbon steel and alloy steel with a carbon content of less than 0.5% are used to avoid sticking to the knife when cutting with a carbon content of less than 0.5%. , while using normalizing treatment. Vacuum annealing and normalizing can still refine the grain and uniform structure, and prepare for the subsequent vacuum heat treatment. Vacuum annealing and normalizing are usually arranged after the blank is manufactured and before rough machining.

2) Aging treatment

Aging treatment is mainly used to eliminate the internal stress generated in blank manufacturing and machining.

In order to avoid excessive transportation workload, for parts with general precision, it is sufficient to arrange an aging treatment before finishing. However, for parts with high precision requirements (such as the box of the jig boring machine, etc.), two or several aging treatment procedures should be arranged. Simple parts generally do not need aging treatment.

3)Vacuum Tempering

Quenching and tempering is to carry out high-temperature vacuum tempering after vacuum quenching. It can obtain uniform and fine vacuum tempered sorbite structure, and prepare for reducing deformation during surface vacuum quenching and nitriding treatment. Therefore, quenching and tempering can also be As a preparatory vacuum heat treatment.

Due to the better comprehensive mechanical properties of the quenched and tempered parts, it can also be used as the final vacuum heat treatment process for some parts that do not require high hardness and wear resistance.

2.Vacuum heat treatment process

The purpose of vacuum heat treatment is to improve mechanical properties such as hardness, wear resistance and strength.

1) Vacuum quenching

Vacuum quenching includes surface vacuum quenching and overall vacuum quenching. Among them, surface vacuum quenching is widely used because of its small deformation, oxidation and decarburization, and surface vacuum quenching also has the advantages of high external strength and good wear resistance, while maintaining good internal toughness and strong impact resistance. In order to improve the mechanical properties of surface vacuum quenched parts, vacuum heat treatment such as quenching and tempering or normalizing is often required as a preliminary vacuum heat treatment. The general process route is: blanking→forging→normalizing (vacuum annealing)→rough machining→quenching and tempering→semi-finishing→surface vacuum quenching→finishing.

2) Vacuum carburizing and quenching

Vacuum carburizing and quenching is suitable for low-carbon steel and low-alloy steel. Firstly, the carbon content of the surface layer of the part is increased. After vacuum quenching, the surface layer obtains high hardness, while the core part still maintains a certain strength and high toughness and plasticity. Carburizing is divided into overall carburizing and partial carburizing. When local carburizing, anti-seepage measures (copper plating or anti-seepage material plating) should be taken for the non-carburized parts. Since the carburizing vacuum quenching deformation is large, and the carburizing depth is generally between 0.5 and 2 mm, the carburizing process is generally arranged between semi-finishing and finishing.

The process route is generally: blanking→forging→normalizing→rough and semi-finishing→vacuum carburizing and quenching→finishing. When the non-carburized part of the local carburized part adopts the process plan of removing the excess carburized layer after increasing the margin, the process of removing the excess carburized layer should be arranged after carburizing and before vacuum quenching.

3) Vacuum nitriding

Nitriding is the process of infiltrating nitrogen atoms into a metal surface to obtain a layer of nitrogen-containing compounds. The nitriding layer can improve the hardness, wear resistance, fatigue strength and corrosion resistance of the surface of the part. Since the nitriding treatment temperature is low, the deformation is small, and the nitriding layer is thin (generally no more than 0.6~0.7mm), the nitriding process should be arranged as late as possible. In order to reduce the deformation during nitriding, it generally takes High temperature vacuum tempering for stress relief.