Vacuum furnaces are highly useful pieces of equipment that can heat metals to extremely high temperatures so that smelting, sintering, brazing, and other kinds of heat treatment can occur. The beauty of a vacuum furnace is that it will heat to a high, consistent temperature and allow no contamination.

In a vacuum furnace, the product is enclosed by a vacuum. The lack of air or other gases inhibits heat transmission with the product through convection and eliminates a source of contamination. The following are some of the advantages of using a vacuum furnace:

Temperature control is possible
Low product contamination by carbon, oxygen, and other gases
Product chilling (quenching) as quickly as possible
To guarantee metallurgical reproducibility, the process can be computer-controlled

High-temperature heating of metals usually results in fast oxidation, which is undesirable. A vacuum furnace eliminates the oxygen, preventing this from occurring.

Once the furnace has done its work, argon – or another inert gas – will be added to the heated metal to reduce the temperature quickly. The gas will be pushed through the furnace and recycled until the correct temperature is reached.

The Temperature Question

We know that a vacuum furnace can withstand high temperatures – that’s its primary function – but just what are those temperatures? How high can they reach? Simply put, the temperature range is between 800 to 3,000oC (which is 1,500 to 5,400oF).

Do You Need A Vacuum Furnace?

The vacuum furnace’s most frequent use is in the thermal processing of certain steels. Accelerated tool steels, alloys for hot or cold machinery, martensitic titanium alloys, precipitation hardening steels, and so on. For working with these steels, a vacuum heat treatment furnace has long been suggested. It is shown that, with this kind of system, the treatment quality is maximized owing to more minor deformations, and a significant cost benefit is achieved.

In many areas of business, there is a continuous requirement to manufacture the finest quality components to the most rigorous product standards. Both long-established and newer materials are being used to satisfy the demands for lighter, stronger, smaller, and more efficient designs, and the employment of vacuum technology in manufacturing is critical to accomplishing these objectives.

Common Vacuum Heat Treatment Processes

Some of the most popular vacuum heat treatment methods are included here, along with a short description of the benefits of vacuum treating.

Annealing

Annealing treatments are used to soften a material, alleviate internal tensions, and/or change the grain structure. Heating to the necessary temperature is followed by soaking at this temperature for sufficient time to enable the material to stabilize, followed by gradual cooling at a slow and often regulated pace. The choice of vacuum annealing is mainly determined by the ease with which cleanliness and high-quality surface finish may be achieved compared to other controlled environment heat treatment procedures.

Brazing

Vacuum brazing is one of the most popular applications for vacuum furnaces. Tight process control and the potential of a clean metallurgical connection at the start of brazing are appealing features. The transportation sector, in particular, has given impetus for increased demand for vacuum furnace brazing. Furthermore, the growing popularity of lightweight, high-strength materials has led to the rise in the popularity of vacuum brazing.