PRODUCT CATEGORIES

Vacuum Heat Treatment Furnace

Vacuum Sintering Furnace

Vacuum Brazing Furnace

Vacuum Hardening of Slender Parts

1. Selection of Process Parameters

Vacuum quenched parts have less deformation, but it must be based on the selection of correct process parameters. For example, the conventional quenching temperature of 9Cr18 steel is 1050~1080°C, and the hardness after quenching is >58HRC. Although it can meet the technical requirements after tempering at 350°C, it is due to quenching. The higher the temperature, the greater the deformation. If heating and quenching at 1060°C is used, the first pass rate of deformation is only about 82% to 91%. We think that the measuring rod is more suitable for sub-temperature quenching. In addition, the greater the cooling rate, the greater the deformation, so the low-pressure gas quenching method should be used as much as possible. We adopt orthogonal experiment method to control heating temperature, heating time and charging pressure. After repeated tests on ZC2-30 air-cooled oil quenching vacuum furnace, we have optimized the best process parameters. After being heated at 1000℃ and filled with nitrogen at 0.067MPa, the deformation of the air-cooled measuring rod is the smallest, and the hardness is 53~54HRC.

In order to reduce the quenching deformation of some high-speed steel tools and dies, increase toughness and increase life, lower temperature quenching can be used, and even 1160℃ quenching is used for W6Mo5Cr4V2 steel tools and dies. For the machine reamer <p2mm, we require both high wear resistance and red hardness, but also good toughness. After many tests, it is heated at 1200℃, nitrogen filling pressure is 0.04MPa, gas quenching, and hardness is 63~ 65HRC, uniform and consistent, deformation is effectively controlled, no secondary carbides are precipitated by metallographic inspection, and the grain size is about 10~10.5.

2. Part Clamping Method and Furnace Loading Method

Reasonable clamping and furnace installation of parts is an effective way to reduce heat treatment deformation. Especially for slender parts, reasonable furnace installation is very important. However, people often do not pay attention to it in production, and the randomness of operators is more Difficult to control deformation. With our low heating temperature and slow cooling, the parts are deformed greatly. According to the experience that the slender part is in an upright state during the whole process, and the uniform compressive stress is maintained around it, the deformation of the part can be reduced. We designed a vacuum hardening special fixture for measuring rod and small reamer, as shown in Figure 1. The fixture material is 1Cr18Ni9Ti stainless steel tube. The parts are neatly and compactly loaded into the fixture, and then hung on the stainless steel rod above the material basket, and fixed with stainless steel to achieve the desired purpose.