Mold vacuum quenching

It’s important to note that the influencing factors of vacuum quenching hardness after a steel grade, size, cooling medium and cooling methods, and under atmospheric pressure, salt bath furnace, pit type furnace, mesh belt furnace, box-type furnace, controlled atmosphere furnace, etc.) of the quenching workpiece, compared to vacuum oil quenching workpiece hardness is uniform, small ripple and slightly higher hardness, mainly lies in the vacuum heating surface is active, not decarburization, do not produce obstruct the cooling of the oxide film and so on, with a diameter of 50 mm high speed steel samples, after vacuum gas quenching, hardness of HRC64, but when the diameter is greater than 100 mm, the hardness of sample is HRC60, Compared with salt bath quenching, SKD11 sample mold steel has a hardness of HRC59~61 after true air quenching and HRC60~63 after oil quenching. Among them, samples larger than 100mm have a hardness below HRC60 after gas quenching and are in the state of incomplete quenching. For 200mm forging die steel SKT4 oil quenching (heating temperature is 800C), the hardness can reach HRC58, can meet the requirements of the use of molds. Large workpieces will precipitate alloy carbides at high temperature, even oil quenching is difficult to avoid this problem, so it is recommended to choose steel with higher hardenability.

Is proved under vacuum heating metal, due to the degassing effect, oxidation and decarburization, therefore after vacuum quenching steel has high mechanical properties, after vacuum quenching can greatly reduce the sensitivity to hydrogen embrittlement of high strength steel of hydrogen content and other gases, make steel of crack instability propagation resistance to brittle fracture.

The service life of the parts after vacuum quenching is significantly improved compared with that of the workpieces after conventional heat treatment. The service life of the mold after vacuum quenching is generally increased by 40%~400% or even 10 times than that of the conventional process, which is attributed to the good surface state after vacuum heating and the instantaneous surface carburizing effect in the process of oil cooling.

Learn More : Vacuum Oil Quenching Furnace