In heat treatment, normalizing is used to refine the grain structure of metals and relieve internal stresses after forging or welding, improving overall toughness.

Vacuum minimizes surface oxidation and ensures uniform heat distribution, requiring a moderate vacuum level around 10⁻¹ to 10⁻² hPa (mbar.)

If vacuum is insufficient, oxidation, scale formation, or temperature gradients can lead to inconsistent microstructure and poor surface quality.

Tempering is applied to previously hardened steel in order to relieve stress and reduce brittleness, improving toughness and ductility.

Vacuum ensures uniform heating for consistent mechanical properties and oxidation-free surfaces, requiring low vacuum levels between 10 and 10⁻³ hPa (mbar) and precise temperature control, typically between 150 and 65°C.

If vacuum is insufficient, uneven tempering may cause residual stresses, reduced toughness, and lead to discoloration or degraded mechanical properties.

Hardening is used to increase the hardness and strength of steel components, typically through austenitizing followed by rapid cooling (quenching).

A stable vacuum atmosphere ensures even heating for a controlled transformation of the material’s internal structure while maintaining a clean environment to prevent oxidation during high-temperature exposure. The process typically requires vacuum levels around 10⁻³ hPa (mbar) and temperatures of 800 to 100 °C, along with an efficient cooling rate.

If the vacuum environment is unstable, the risk for distortion, incomplete transformation, or surface decarburization increases, all of which can reduce final hardness and part quality.

Surface hardness and wear resistance of low-carbon steels are improved by Low Pressure Carburizing (LPC), which diffuses carbon into the surface at low pressure.

Vacuum maintains a controlled atmosphere for precise carbon diffusion, ensuring uniform case depth and avoiding unwanted reactions, typically requiring a vacuum range of 1 to 10⁻² hPa (mbar), accurate temperature control around 900 and 1050 °C, and the ability to handle alternating gas cycles (e.g., acetylene, propane).

If vacuum is insufficient, the process may become unstable, leading to longer cycles, inconsistent case depth, and a risk of surface oxidation, affecting part quality and hardness.

Plasma nitriding is used to enhance surface hardness, wear resistance, and corrosion protection by diffusing nitrogen into the surface using ionized plasma.

Vacuum enables plasma generation and ensures uniform ion energy at the part surface, typically requiring vacuum levels of ~10⁻² to 10⁻³ hPa (mbar), pulsed DC or RF power, and precise gas control using nitrogen-hydrogen mixtures.

If the vacuum is unstable – or breaks down entirely – the plasma may become irregular or extinguish, leading to incomplete nitriding, which results in reduced surface quality, adhesion, and wear resistance.

In powder metallurgy, sintering is used to produce dense, complex parts by bonding particles through diffusion and partial melting.

During debinding, vacuum removes binders and vapors in a clean environment without re-deposition; during sintering, it enables high-temperature particle diffusion and prevents oxidation during material densification. These steps differ significantly in requirements: debinding demands high pumping speed and vapor protection, while sintering requires a stable high vacuum around 10⁻⁴ hPa (mbar).

If vacuum is insufficient, binders may remain, leading to weak or porous parts, and presence of air during sintering can cause oxidation, brittleness, or surface defects.

It is just like regular heat treating – but with all the air (and trouble) removed. Vacuum heat treating involves heating metals in a sealed, oxygen-free environment to improve their hardness, strength, or stability without oxidation, scale, or contamination. The result? Clean, high-performance parts that are ready for action.

Learn more in our vacuum technology book

A vacuum environment is essential in heat treatment for delivering consistent quality and enhancing the mechanical properties of metal alloys. Whether you are hardening or stress relieving by annealing, controlling the vacuum atmosphere ensures clean, precise results.

A vacuum furnace is a sealed chamber where metals are heat treated in a controlled, oxygen-free environment. Vacuum pumps remove air to prevent oxidation and contamination, while allowing precise temperature control, pressure, and atmosphere. It is essential for processes that demand clean surfaces, precise material properties, and repeatable results.

Vacuum furnaces are built for the process – always. While there is no standard model, a few common types and variations stand out:

Strictly speaking, brazing is not heat treatment process – it is a joining method. However, since it involves controlled heating in a vacuum furnace, it often shares the same neighborhood. Here is why vacuum brazing stands out:

Because not all vacuum conditions are created equally – and neither are your process demands. Some applications release condensables, binders, or dust, which calls for robust oil-sealed vacuum pumps or tolerant diffusion systems. Others require a clean, oil-free environment, so dry screw vacuum pumps or turbomolecular vacuum pumps with dry backing pumps are a better fit. It all comes down to what you are pumping:

Pfeiffer covers more than just heat treatment – we support the entire metallurgical vacuum chain, from steel degassing at the start to protective coatings at the finish.

We offer every required vacuum solutions from a single source: vacuum pumps, gauges, leak detectors, gas analyzers, valves, components – all selected and configured for your task. One partner, one system. Fully tailored to your process.

With our experience and comprehensive portfolio, we are ready to support furnace builders and users with reliable vacuum technology, customized solutions, and practical expertise.

Your process drives what we do – and we are here to keep your vacuum solutions performing, cycle after cycle.

Know your pressure, all the time

Accurate pressure measurement forms the basis of effective vacuum control. Whether for rough or high vacuum, real-time pressure data keep you always within specifications.

Keeping your system tight

Even the most advanced furnace is only as good as its vacuum integrity. Regular leak checks are essential to maintain process reliability, especially under high thermal and mechanical stress.

Know what is inside

Outgassing, contamination, or unexpected process gases?

See what’s really in your vacuum. From water vapor to hydrocarbons, our PrismaPro mass spectrometer gives you insight into your process atmosphere – allowing real-time analysis and early detection of process deviations.

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