Low temperature tempering process
The vacuum tempering furnace relates to a heating and operation control device of a high-power spring continuous tempering furnace. Its characteristics include a box, a programmable controller installed in the box, a plurality of heating control components, a touch control panel mounted on the panel of the box, a temperature recorder, a functional switch and an indicator lamp, and various groups of heating control units. The heating elements and two thermocouples are respectively located in each heating area divided in the furnace; the temperature regulators in the heating control parts are connected with solid state relays and two thermocouples respectively; the solid state relays are connected with heating elements; and the two thermocouples are connected with temperature recorder; this device is more energy-saving than the vacuum furnace. The programmable controller is connected with touch control screen, temperature regulator in each group of heating control parts, heat mixing fan, solenoid valve and motor in transmission device, and functional switch and indicator are connected with corresponding control parts. The device has high temperature precision in the furnace, long effective temperature time in the furnace, automatic feeding and discharging, and 40% productivity increase.
Processing method of low temperature tempering furnace:
1) The cryogenic treatment box with continuous computer monitoring and automatic regulation of liquid nitrogen input and automatic temperature rise and fall is used.
2) The treatment process consists of three procedures: precisely compiled cooling and super-low temperature holding and rising along with temperature.
The reasons why cryogenic treatment can improve performance are analyzed as follows:
1) It transforms austenite with lower hardness into martensite with higher hardness, stability, wear resistance and heat resistance.
2) Carbide particles with higher hardness and finer particle size are widely distributed in the lattice of the treated materials by ultra-low temperature treatment.
3) Smaller and more uniform microstructures with higher densities can be produced in metal grains.
4) Due to the addition of micro-carbide particles and finer lattices, the denser molecular structure is resulted, which greatly reduces the tiny voids in the material.
5) After ultra-low temperature treatment, the internal thermal stress and mechanical stress of the material are greatly reduced, which effectively reduces the possibility of tool and tool cracking and edge collapse. In addition, because the residual stress in the tool affects the ability of the cutting edge to absorb kinetic energy, the tool after ultra-low temperature treatment not only has high wear resistance, but also its own residual stress harm is greatly reduced than that of the untreated tool.
6) In the treated cemented carbides, new combinations of molecular structures are produced due to the reduction of electronic kinetic energy.