PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Meeting standards for die vacuum heat treatment

(1) Precautions for mold vacuum heat treatment

①The mold material contains more alloying elements, and elements with higher vapor pressure (Al, Mn, Cr, Si, Pb/Zn/Cu) are prone to element evaporation when heated in vacuum. Therefore, the degree of vacuum during quenching and heating should be properly controlled to prevent volatilization of alloying elements.

②Reduce the thermal stress and tissue stress caused by the temperature difference between the inside and outside of the heating mold. For complex molds with large cross-sections, multiple preheating is required, and the heating rate is not required to be too fast.

③ For air-cooled or oil-cooled die steels with large cross-sections such as high-speed steel, high-Cr steel and 3Cr2W8V, it is recommended to process them in a high-pressure gas quenching furnace. If the air cooling speed is not enough, vacuum oil quenching must be carried out. The cooling process of air cooling and oil quenching is adopted. The purpose is to prevent the appearance of white and bright layer organization on the surface of the workpiece.

④The heating temperature of vacuum quenching can basically be the same as or slightly lower than that of salt bath heating and air heating.

⑤ Whether the workpiece is loaded into the furnace is reasonable or not has a great relationship with the quality after heat treatment. Considering that vacuum heating is mainly based on radiation, the workpiece should be properly placed in the furnace, and small parts need to be separated by metal mesh to ensure uniform heating and cooling. For high-speed steel workpieces, contact should also be avoided, otherwise the workpieces will stick to each other due to the volatilization of some metals during heating.

(2) Process parameters of vacuum heat treatment for hot work die steel materials

The vacuum heat treatment of hot work die steel adopts heating and cooling to obtain the microstructure and mechanical properties requirements. Therefore, the vacuum heat treatment heating equipment is the root of the mold heating. Only by deeply understanding the heating performance of the equipment can the heating of the mold be determined. temperature and holding time.

(3) Process specification for vacuum heat treatment of molds

Under the premise of correct material selection and design, how to improve the service life of the mold is a concern of heat treatment workers. The proportion of early failure of the mold due to improper vacuum heat treatment of the mold accounts for 44% to 70%. It can be seen that it should cause high Pay attention, which includes improper process formulation, improper operation or violations, process specifications or codes that do not meet actual requirements, improper selection of vacuum heat treatment equipment, etc., resulting in mold hardness, metallographic structure, deformation, surface oxidation and decarburization, serious Therefore, how to ensure that the product quality during the mold heat treatment process meets the process and design requirements is also the key to improving the service life of the mold.

After vacuum heat treatment, the mold can obtain performance and effects that cannot be obtained by general heat treatment, and its service life is greatly improved, generally by 40% to 400%. In addition, vacuum heat treatment can reduce the machining allowance (grinding or polishing) by 1 /3~1/2, so the machining allowance after heat treatment is reduced, the production efficiency is improved and the manufacturing cost is reduced, so the use of vacuum heat treatment for tools and molds has become the development trend of the mold industry, and it shows huge advantages and prospects.

(4) The vacuum cooling method and characteristics of the mold

Vacuum quenching cooling should be determined and selected according to the shape, material, size and technical requirements of the mold. At present, the cooling methods of vacuum quenching mainly include oil cooling quenching, vacuum air quenching, high pressure gas quenching, vacuum nitrate salt quenching and vacuum water quenching. Quenching, etc., they have different scope of application.

a.Vacuum oil quenching. It is suitable for mold steel such as alloy tool steel, high-carbon high-chromium alloy steel, high-speed tool steel, and some measuring tools. It is quenched with special vacuum oil. It has a wide range of applications and accounts for about 60% of the total heat treatment of mold steel.

b.2bar vacuum gas quenching. The maximum cooling pressure of nitrogen gas quenching is 2bar, so it is called low-pressure vacuum air quenching. The purity of nitrogen gas is above 99.95%, and its application range is narrow. .

c.6bar high pressure gas quenching. The nitrogen quenching pressure is above 6 bar. When the nitrogen pressure of 4Cr5MoSiV1 steel is 9.5 bar, compared with oil cooling and salt bath cooling, it shows that the high air cooling pressure not only increases the cooling speed, but even makes the cooling speed reach or exceed The cooling rate of oil, so far, is the most ideal and most widely used gas quenching furnace for processing tools and molds. It is suitable for quenching treatment of high-speed tool steel, high-carbon and high-chromium alloy steel, and some alloy tool steel molds.

d.10bar ultra-high pressure gas quenching. The furnace can handle all high-speed steel, hot work die steel, cold work die steel, Cr13 steel and some oil-quenched alloy steels, and can be hardened under intensive charging conditions, but its current application is less.