PROCEDURE
Hardening
Hardening is a heat treatment process used to increase the hardness and strength of metals such as steel. Most materials consist of different crystal lattice structures that have different properties. Hardening is a process in which these structures are changed in order to achieve the desired properties.
Our hardening processes
at a glance
Vacuum hardening
During vacuum hardening, your component is heated in a vacuum and then quenched using pressurised nitrogen. As a rule, high-alloy tools are vacuum hardened.
Inert gas hardening
During inert gas hardening, the metallic component is brought to the hardening temperature in an inert gas atmosphere and then rapidly cooled in an oil bath. As a rule, low-alloy materials are refined in this way.
Induction hardening
In induction hardening, the areas to be hardened are heated using induction current and then quenched using a water spray if required
Hardening processes
in comparison
| Criteria | Vacuum Hardening | Protective Gas Hardening | Induction Hardening | Case Hardening |
|---|---|---|---|---|
| Medium | Vacuum (oxygen-free) | Nitrogen, argon, methane | Induction coil (electric field) | Carbon-rich gas / atmosphere |
| Temperature range | Approx. 900–1250 °C | Approx. 750–950 °C | Surface: 800–1000 °C | Carburizing: 850–950 °C, Hardening: ~800 °C |
| Hardening depth | Full cross-section | Full cross-section | 0.5–5 mm (adjustable) | 0.2–2 mm (diffusion layer) |
| Depth control | Limited (material-based) | Limited | Precisely adjustable | Yes, via carburizing time |
| Distortion | Very low | Low to medium | Low | Medium to high |
| Typical hardness | >60 HRC (depending on steel) | 50–64 HRC | >55 HRC (surface) | ~60–65 HRC (surface) |
| Typical applications | Tools, precision parts, molds | Machine parts, mass production | Gears, shafts, bearing surfaces | Transmission parts, crankshafts, piston pins |
| Surface quality | Excellent, bright surface | Good (low oxidation possible) | Rough, may need post-processing | May be oxidized, often needs finishing |
| Environmental impact | Very low (clean process) | Moderate | Low (localized process) | Moderate (gas emissions) |
| Special features | No scaling, clean parts | Cost-effective for series | Fast, selective, energy-efficient | Combines hardness & core toughness |
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Advantages of hardening
briefly summarised::
- Increasing hardness and strength: Hardening changes the crystal lattice structure of the material and thus increases its hardness and strength, making it more suitable for higher loads and stresses.
- Improved wear resistance: Hardening increases the surface hardness of the material, which improves its resistance to abrasion, damage and wear.
- Extending service life: Due to the improved hardness and strength, hardening extends the service life of the material and increases its reliability.
- Increasing corrosion resistance: Some hardening processes also improve the corrosion resistance of the material by forming a protective layer on the surface.
- Increasing thermal stability: Hardening can also increase the thermal stability of the material, making it more suitable for high temperatures and changing thermal conditions.
- Reduction of tolerances and distortion: Hardening can also improve the precision and accuracy of the material by reducing tolerances and distortion.
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FAQs
Frequently asked questions about hardening
Hardening is a heat treatment process used to increase the hardness and strength of metals such as steel. Most materials consist of different crystal lattice structures that have different properties. Hardening is a process in which these structures are changed in order to achieve the desired properties. Hardening can be carried out in various ways, including flame hardening, induction hardening, gas fire hardening, inert gas hardening and vacuum hardening. Each method has its own advantages and limitations and is selected based on the specific requirements and properties of the material.
Materials are hardened to improve their properties. Hardening changes the internal structure of the material and leads to greater strength, hardness, toughness and abrasion resistance. This allows the material to perform better under load and wear. Hardening is therefore an important process in many areas, such as the manufacture of tools, machine and vehicle parts.
Many materials can be hardened, including
- Steel: Steel is the most commonly hardened material and is often used in tools, machinery and vehicle parts.
- Aluminium: Aluminium can be hardened by heat treatment to make it more resistant to damage.
- Copper: Copper alloys can be hardened by heat treatment to make them more suitable for certain applications such as electrical conductors.
- Titanium: Titanium can be hardened by heat treatment to make it more resistant to corrosion and abrasion.
- Nickel-based alloys: Nickel-based alloys are often hardened in high temperature applications to increase their strength and hardness
Hardening is a process in which a material, usually steel, is heated and then rapidly cooled to increase its hardness and strength. Here is an overview of the hardening process:
- Pre-treatment: before hardening begins, the material is usually cleaned and pre-treated to ensure it is ready for the hardening process. This may include removing rust, oil and other contaminants as well as grinding or sanding the material.
- Heating: The material is heated to a specific temperature. The exact temperature depends on the type of material and the desired degree of hardness.
- Cooling: After heating, the material is cooled quickly to achieve the desired hardness. This can be done by bathing in oil, air hardening or cold hardening.
- Quenching: After cooling, the material is usually quenched to stabilise the hardness.
- Testing: Finally, the hardened material is tested to ensure that it has reached the desired degree of hardness.
Overall, hardening is a complex process that requires careful monitoring and control. However, carrying out the hardening process correctly can help to improve the performance and longevity of tools and machines.