Vacuum quenching refers to the smooth quenching of parts. The quenching and cooling of parts are carried out in the vacuum furnace, and the quenching medium is mainly gas (such as inert gas), water and vacuum quenching oil. Vacuum quenching has been widely used in the quenching of various carburizing steels, alloy tool steels, high speed steels and stainless steels, as well as the solution treatment of various aging alloys and hard magnetic alloys.

There are two kinds of quenching in vacuum: gas quenching and liquid quenching. Gas quenching is that the workpiece is heated in vacuum and then cooled by high purity neutral gas (such as nitrogen) in the cooling chamber. High speed steel and high carbon and high chromium steel are suitable for gas quenching. Liquid quenching is to heat the workpiece in the heating chamber, move it to the cooling chamber, fill it with high purity nitrogen, and immediately send it to the quenching oil tank for rapid cooling. If high surface quality is needed, tempering and precipitation hardening after vacuum quenching and solution heat treatment should still be carried out in vacuum furnace.