Havar® Disk

Havar® (UNS R30004) is a precipitation-hardenable cobalt-chromium-nickel alloy with additions of tungsten, molybdenum, and manganese. In disc form it delivers the same combination of high tensile strength, radiation stability, non-magnetic behaviour, low outgassing, and corrosion resistance as the rest of the Havar® range, in a pre-profiled circular geometry that seats directly into flanged target holders, pressure transducer housings, and vacuum window assemblies without requiring blanking from flat sheet.

Cold rolling is the primary source of Havar®'s mechanical strength. A minimum of 80% cold work is required before age hardening to develop peak tensile and fatigue properties. The disc arrives cold-rolled and ready either for direct use or for age hardening as a final processing step — but all secondary operations, including profiling, drilling, and welding to mounting hardware, must be completed before age hardening is applied. Once fully treated, the material is significantly harder and will not tolerate further deformation.

The circular disc geometry makes Havar® ideal for cyclotron target entrance windows, particle detector entrance windows, and beamline entrance windows. The disc seats directly in a flanged or threaded target holder and seals the boundary between the pressurised target liquid and the vacuum-side beam optics. Its high tensile strength allows it to withstand that differential pressure without creep or fatigue failure over extended irradiation campaigns. Radiation stability ensures the window properties do not degrade during service, and the low outgassing rate means no contamination of the downstream vacuum environment.

Yes. Havar® disc is used in pressure diaphragms, burst disc pressure relief devices, and diaphragm seals in pressure transducers and differential gauges. Its fatigue resistance under cyclic loading, dimensional stability, and non-magnetic behaviour make it reliable in demanding pressure measurement environments — particularly where stainless steel diaphragms are ruled out by magnetic sensitivity requirements or where the process fluid is corrosive enough that a chromia-passivated cobalt-chromium alloy is needed for long service life.

Laser cutting is the preferred method for producing precision circular discs, delivering clean burr-free edges, tight diameter tolerances, and a minimal heat-affected zone. This is particularly important for fully hardened material, where mechanical cutting would introduce edge cracking. Both CO₂ and fibre laser systems are applicable. Wire EDM is an effective alternative for high-precision disc and ring profiles, offering non-contact material removal that avoids the work-hardening and tool wear associated with conventional machining of this alloy. For cold-rolled material prior to age hardening, precision blanking with hardened carbide tooling is also feasible.

Yes. Electron beam and laser welding are the correct joining methods for Havar®, producing hermetic high-integrity bonds with precise heat input and a minimal heat-affected zone. This is essential for thin-disc window assemblies where any heat-induced dimensional change would compromise seating and leak-tightness. Unlike Elgiloy® and Phynox®, Havar® is not suited to TIG welding — the less controlled heat input degrades fatigue performance in the weld zone, which matters in cyclic pressure or beam-on/beam-off service.

Havar® disc offers dimensional stability from cryogenic temperatures up to 400 °C under load and retains a significant proportion of room-temperature strength above 500 °C — considerably better elevated-temperature performance than Elgiloy® or Phynox®, which are limited to approximately 315 °C. Oxidation resistance in air extends to approximately 800 °C. For applications in which a diaphragm or window operates in a thermally cycling environment, Havar®'s tungsten addition stabilises the cobalt matrix and slows the thermally driven processes that would degrade strength in conventional alloys.

Yes. Havar®'s extremely low outgassing rate makes it fully compatible with high-vacuum and ultra-high-vacuum environments. It is used in synchrotron beamline windows, alpha spectrometry windows, time-of-flight mass spectrometry windows, and plasma physics and fusion research chamber windows. The disc format is particularly practical in these settings because it can be laser welded or EB welded directly into a flange assembly to form a clean, hermetically sealed window unit.

Havar®'s magnetic permeability of µr ≈ 1 is intrinsic to the cobalt-chromium matrix and is retained after cold rolling and age hardening. This eliminates the field distortion that ferritic or work-hardened austenitic stainless steel diaphragms would introduce near particle detectors, MRI magnets, beam transport optics, and magnetically sensitive pressure transducers. It is also a hard requirement for MRI-compatible device enclosures and implant-adjacent components where any ferromagnetic response is unacceptable.

Havar® achieves the highest peak tensile strength of the three alloys and offers superior elevated-temperature stability and radiation resistance. For pressure diaphragms operating at high stress amplitude or elevated temperature, and for any application involving radiation exposure, Havar® is the primary choice. Elgiloy® and Phynox® have higher molybdenum content, giving better pitting and crevice corrosion resistance in chloride-rich process fluids — if the service environment involves prolonged chloride exposure, they are more appropriate. Phynox® is also the preferred specification for implantable medical assemblies in European regulated markets due to its more comprehensive ISO 10993 characterisation.

Yes. Custom diameters, thicknesses, edge finishes, and laser-profiled features can be supplied with no minimum order quantity. Request a quote with your dimensions, required condition, and any secondary feature requirements and we will confirm what is achievable.

Choose disc when the component is circular in plan and used in an axial mounting arrangement — it removes the blanking and edge-finishing step that would be needed when cutting a circular piece from flat foil. Foil cut pieces suit low-volume or irregular-geometry applications such as beam monitor foils and custom hermetic barriers. Coil provides continuous strip for automated stamping, spring winding, and progressive die operations where length and throughput matter.