Process-safe refinement of austenitic stainless steels: Solution annealing, stress-relief annealing, Vacuum-brazing & EB welding. Clean, leak-proof assemblies – from prototype to series production.
Austenitic stainless steels such as 1.4301/304, 1.4404/316L or high-alloy variants combine excellent corrosion resistance with good workability and are the first choice for clean, media-resistant and vacuum-compatible components. Listemann optimizes such components through Heat treatment, Vacuum-brazing (Brazing) and Electron beam welding (EBW) – consistently in a vacuum, reproducible and documented. The results are bright surfaces, high tightness and tight tolerances right through to series production.
Solution annealing & stress relief annealing: homogeneous microstructure, reduced residual stresses, optimum corrosion resistance.
Vacuum-brazingCapillary-proof gap filling, flux-free, very good surface quality.
EB weldingdeep, narrow seams, minimal heat-affected zone, low distortion.
Surface preparation & cleaning: defined roughness, low-particle processes.
Qualification & testing: Tightness, tensile/shear tests, metallography, CT as required.
Vacuum and process technology, heat exchangers, valves, sealing components
Medical technology assemblies with flawless surfaces
Semiconductors/equipment: low-particle components
Apparatus, machine and food technology
Austenites are characterized by a non-hardenable, tough matrix, good cold formability and excellent corrosion resistance in many media. However, they react sensitively to the influence of heat (e.g. sensitization/chromium carbide formation in borderline cases) and therefore require clean, controlled processes. Vacuum-guided processes minimize oxidation and tarnishing, ensure surface quality and help to ensure low particle and residue levels for cleanroom and vacuum applications.
Austenitic steels are well suited to Vacuum-brazing, as flux-free processes enable bright surfaces, high tightness and reproducible quality.
Depending on the application temperature and medium, mainly nickel, silver or precious metal-based solders are used, which are selected on a project-specific basis according to strength, tightness and resistance.
For capillary-proof soldering, uniform gaps in the range of around 0.02 to 0.08 millimeters are useful, as they support wetting, tightness and strength.
In the solution-annealed condition, austenitic steels are essentially non-magnetic, but can become slightly ferromagnetic through cold forming or welding.
Unfavourable temperature-time sequences can lead to chromium carbide precipitation at grain boundaries, which promotes intercrystalline corrosion; controlled cycles and stabilized/LC qualities minimize this risk.
For hybrid connections, for example to copper, titanium or ceramics, suitable solders or interlayers and geometries adapted to the thermal expansion coefficient are used to avoid stresses and brittle phases.
Solution annealing to homogenize the microstructure and restore corrosion resistance as well as stress relief annealing to reduce distortion are the typical heat treatments for austenitic steels.
Electron beam welding is an excellent option because it creates narrow, deep seams with a small heat-affected zone and minimizes distortion and rework.
Phone: +41 52 245 18 55
Mobile: +41 77 442 46 91
t.bachmann@listemann.com
Phone: +423 375 90 12
Mobile: +423 78 05 401
t.bitschnau@listemann.com
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