PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Why Heat Treat in a Vacuum

Vacuum heat treatment method

The vacuum heating method is selected according to the requirements of heating equipment, workpiece and vacuum heat treatment characteristics. There are four methods: cold furnace charging, warm charging, high temperature charging and low temperature charging. The heating characteristics of cold furnace charging are small heating speed, convenient furnace loading, suitable for high-alloy steel parts with complex shapes and large castings and forgings, etc.; heating characteristics of warm charging furnace are high heating speed, convenient operation and wide application; The heating feature of high-temperature furnace is that the furnace temperature is 100-150°C higher than the heating temperature, so the heating speed is high, and the cross-section temperature difference is large, and the operation is difficult. It is suitable for vacuum annealing and normalizing of forgings, vacuum quenching of small workpieces, etc.; low-temperature furnace heating It is characterized by slightly higher heating speed and smaller temperature difference, and is suitable for workpieces with lower heat treatment temperature and preheated workpieces.

Vacuum Heat Treatment Options for Parts

Due to the different composition, size, original structure and heat treatment process requirements of the parts, the selection of heating speed is also different. In actual production, the following points should be paid attention to. the

(1) The heating rate of steel with high plasticity can be selected higher, while the heating rate of high brittleness should be selected lower; the heating rate of small-sized carbon steel and low-alloy steel can be increased, while the large-sized parts should use a higher heating rate. Small heating rate. the

(2) For steel with poor thermal conductivity (such as high-speed steel, etc.), a lower heating rate should be selected, otherwise the large temperature difference between inside and outside will cause deformation and cracking. the

(3) For workpieces with complex shapes, large differences in cross-sectional dimensions, large residual stress and uneven structure, the heating rate should also be lower. the

(4) Due to the serious composition segregation and inclusions in the steel, the material structure is uneven, and the heat conduction of various parts of the steel is inconsistent, especially the thermal stress concentration at the tip of the large inclusions, which can easily cause cracking and should be heated slowly.

Vacuum heat treatment heating time

The heating time in the general vacuum heat treatment process includes three parts: heating, soaking and heat preservation. In actual production, the heating time of steel parts should be determined according to the effective thickness of the workpiece, usually obtained by empirical data or empirical calculation method. the

(1) Heating time: refers to the time for the surface of the workpiece to be heated to the heating temperature after it is loaded into the furnace. the

(2) Soaking time: refers to the time when the center temperature of the workpiece rises to close to the surface temperature after the surface of the workpiece reaches the heating temperature. the

(3) Holding time: refers to the time for maintaining constant temperature after soaking to meet the process requirements such as tissue transformation and carbide dissolution. Of course, the soaking time may not be considered for thin workpieces, but the soaking time is only considered for particularly large workpieces or when the furnace load is very large.