Machining of hardened steel
Hardened steel refers to alloyed or non-alloyed steels that have undergone heat treatment (quenching + possibly tempering) to increase their hardness and mechanical strength while maintaining a certain toughness. At MicroMécanique, we use hardened steel as a base technical material to produce demanding parts: tools, mechanical components subjected to high stress, guide systems, etc. We master not only the machining of hardened steel after treatment, but also other operations like finishing, grinding and polishing, with micron-level precision.
Examples of products and possible applications
Here are some examples of products MicroMécanique has the capability to develop or produce from hardened steel:
- Transmission shafts, crankshafts and other shafts subjected to torsion and high mechanical stress.
- Pinions, gears, machine teeth and gearbox parts
- Drive parts, connecting rods, shafts and axles
- Tooling: dies, moulds, impressions, tool plates and punches
- Guide systems, rails, slides and precision components for special machines
- Parts with tight tolerances for watchmaking, luxury goods or measuring instruments
- Cylinder barrels, parts resistant to fatigue or mechanical wear.
Properties of hardened steel
Property | Description |
Hardness | After quenching, hardened steel can reach a Rockwell hardness of around 50 to 65 HRC, depending on the grade and cross-section. |
Tensile strength and yield strength | Very high, potentially exceeding 800 MPa depending on the alloy and treatment. |
Toughness | Tempering reduces the brittleness caused by quenching and enables a suitable compromise between hardness and toughness. |
Dimensional stability | Limited thermal expansion, stability at high temperatures, good resistance to temperature variations. |
Wear resistance | Good resistance to abrasion and friction, especially with precise finishes or additional surface treatments (coating, nitriding, etc.). |
Fatigue resistance | This is important, especially for parts subjected to load cycles: hardened steel alloys with good tempering and surface treatments can improve fatigue resistance. |
Hardenability | This depends on the chemical composition (carbon content, alloy elements) and the cross-section of the part: the thicker the cross-section, the better the alloys must be designed to ensure consistent hardness throughout. |
Machining techniques we use (or can use) at MicroMécanique
Below are the processes that MicroMécanique offers and can offer for hardened steel, by achieving the relevant technical feats:
- 5-axis/multi-axis high-speed machining (HSM) for certain complex parts, particularly when conventional machines have limitations when it comes to complex designs. Our machines are also equipped with a grinding module.
- Wire and spark EDM
- CNC milling/turning: direct machining of hardened steels, often replacing or reducing the need for grinding. Very useful for reducing cycle times.
- Surface and cylindrical grinding: to achieve high-precision surfaces, very smooth finishes and tight tolerances.
- Microdrilling and drilling in hardened steel: demanding in terms of tools (very hard inserts or tools, often coated, sometimes CBN) and cutting parameters (low speeds, generous lubrication).
Would you like to work with hardened steel?
Discover its applications
Sectors in which hardened steel is particularly useful, and where MicroMécanique can add significant value:
- Aeronautics and space: structural parts, shafts, gears, guide systems, where weight, strength, tolerances, lifespan and safety are critical.
- Automotive: engine components, transmission, connecting rods, shafts, suspension parts, bodywork or chassis elements subject to mechanical fatigue.
- Tools and moulds: injection moulds, dies, forming tools and cavities subjected to extreme wear and repeated stress.
- Watchmaking and luxury goods: delicate mechanical components requiring extreme dimensional precision, stability and a very careful finish.
- Special purpose machines and tooling for heavy industry: demanding gear parts, rotors, flywheels and rotary systems.
- Defence industry: high-strength components, armoured parts, elements subjected to shocks, vibration and extreme use.
- Equipment and components subjected to extreme fatigue and vibration: guide systems, bearings, thrust bearings, bushings, etc.