9SiCr die steel vacuum heat treatment

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9SiCr steel is a kind of low alloy steel for cutting tools. It is widely used in China and is often used in cold work molds, which has played a very good role. Compared with chromium steel (Cr2 or 9Cr2), 9SiCr steel has higher hardenability and hardenability, and has excellent tempering stability. Traditional cutting tool steel parts are mostly quenched by salt bath, box-type resistance furnace or protective atmosphere furnace, but the vacuum heat treatment process has more significant advantages. Compared with ordinary resistance furnaces, vacuum heat treatment can control the heating and cooling speed well, so the 9SiCr die steel has less oxidation degree, less decarburization, good surface gloss and small deformation during the heating process. This increases the toughness and service life of the part.

The application range of 9SiCr steel

9SiCr die steel parts have good hardenability, and grading or isothermal quenching is often used to reduce the deformation of parts during heat treatment. For example, in the manufacture of bolt cross groove punches, 9SiCr is heated at 900 °C, and then kept at 260~280 °C for 30 minutes. Its hardness and impact toughness are 3 times higher than those of conventionally treated punches, and the service life is also longer. For another example, 9SiCr steel is used to make punching dies when making concave and convex dies with complex shapes. In addition, the steel is used to make thread rolling dies, rolling plates, cold heading dies, etc. It can also be used to produce punches, embossing dies, drill bits, reamers, etc., and can also be used to produce some precision parts dies or high Precision modulus, etc.

9SiCr die steel commonly used heat treatment process

The main heat treatment processes of 9SiCr steel are: (1) Forging heat quenching and tempering treatment, usually the temperature is raised to 900 ° C and then oil quenched, and then lowered to 700 ~ 720 ° C for high temperature tempering (2) Normalizing, at 900 ~ Hold at 920℃, the holding time of salt bath furnace and air-cooled furnace are 25~30s/mm and 70~90s/mm respectively; (3) Spheroidizing annealing, hold at 790~810℃ for 2~4h, furnace cooling After that, adjust the temperature to 700~720℃ for 3~4h, then cool down to 500~600℃ with the furnace at a cooling rate of not less than 30℃/h, and finally take out the parts and carry out air cooling (4) Quenching and tempering treatment , firstly quench at 880~890℃, and then carry out oil cooling. Then adjust the temperature to 680~700 ℃ for tempering heat treatment (5) cryogenic treatment, heat up to 870 ℃ and then carry out quenching treatment, then heat preservation and tempering at 200 ℃ for 1 hour, and finally carry out cryogenic treatment at -196 ℃ for 10 Hour.

Vacuum heat treatment

Vacuum heat treatment process refers to a new heat treatment technology developed by combining vacuum technology with heat treatment technology. This process is mainly to place the parts in a heating furnace and ensure a certain vacuum effect for heat treatment. The process can be subdivided into four types: low vacuum, medium vacuum, high vacuum and ultra-high vacuum.

Vacuum heat treatment process

The equipment used in the heat treatment process is a double-chamber vacuum oil quenching furnace. When a vacuum furnace is used to heat 9SiCr steel, the vacuum furnace should be evacuated in advance, and the pressure should be adjusted to below 13.3Pa, so that the heating of the parts is at a pressure of 1.33~13.3Pa, and then oil quenching is carried out under the protective atmosphere of argon. , keep the pressure at about 5×10*4Pa.

After using the vacuum furnace, due to its slow heating speed, the parts are heated evenly during the heating process, the thermal stress is reduced, and the deformation amount is reduced, which is obviously better than the heat treatment process of the ordinary resistance furnace. In addition, compared with ordinary resistance furnaces, most of the remaining gases during heating in vacuum furnaces are organic vapors such as water vapor, carbon dioxide, and grease. These conditions make the surface of the part in an active state, and it is not easy to form oxidation, decarburization and other phenomena, so that the surface finish of the part is better, and the hardness and wear resistance are improved. Moreover, since the cooling rate of each surface during the oil quenching process in vacuum heat treatment is relatively uniform, it is not easy to form an oxide film that hinders cooling. In addition, after tempering, more fine acicular martensite structure is obtained in the part, so both impact toughness and tensile strength are improved. At the same time, the uniform heating method of vacuum heat treatment makes the distribution of carbides in the part uniform, and the dimples of the fracture increase after heat treatment, which improves the toughness of the part.

Equipment selection: The VOGQ series vacuum heat treatment furnace produced by SIMUWU is a high-quality product for the vacuum heat treatment process of tooling and molds. Good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum heat treatment process. SIMUWU specializes in the manufacture of vacuum furnaces, has more than ten years of relevant experience, and has a good reputation in the field of vacuum furnace manufacturing. The product line includes vacuum air quenching furnace, vacuum oil quenching furnace, vacuum brazing furnace, etc., which are widely sold in developed and developing countries.