Havar® Coil

Havar® (UNS R30004) coil is the precipitation-hardenable cobalt-chromium-nickel alloy supplied in continuous strip format on a spool. The coil format delivers the uninterrupted length needed for automated stamping, spring winding, diaphragm production, and roll-to-roll converting. Because Havar® derives its high strength primarily through cold reduction, the strip arrives already at or near peak strength — ready for age hardening once all forming and blanking operations have been completed.

Cold rolling is the dominant strengthening mechanism. A minimum of 80% cold work must be applied before age hardening to develop maximum tensile and fatigue properties — a more intensive requirement than Elgiloy® or Phynox®, which respond to age hardening after substantially less cold reduction. Havar® coil is supplied in the cold-rolled condition, meaning the strength is already built in. Age hardening at 538 °C (1,000 °F) is the final step, applied only after all cutting, forming, stamping, and joining are complete.

Havar® has a high work-hardening rate in the cold-rolled condition, which requires conservative process planning. A minimum bend radius of 8× material thickness is required for 90° bends to avoid cracking or delamination — more conservative than Elgiloy® or Phynox®, which permit bends at 5× thickness. Stamping and blanking are best performed before age hardening, using hardened tooling with close attention to punch-to-die clearance and edge quality. Once fully age-hardened, the strip is significantly harder and will not tolerate further forming.

Havar® exhibits excellent fatigue resistance under cyclic loading, with a fatigue endurance limit that significantly exceeds austenitic stainless steels at comparable stress amplitudes. Its high strength translates directly to a higher fatigue endurance limit in spring and diaphragm applications subject to sustained high-cycle loading. Combined with non-magnetic behaviour and corrosion resistance, this makes it suitable for power springs, flexible structural components, and precision medical springs. For the most demanding implantable spring applications — cardiovascular stents and guidewires, for example — Elgiloy® and Phynox® have a more extensive published fatigue dataset specific to those device categories.

Havar® coil strip is used to produce pressure diaphragms, burst disc pressure relief devices, diaphragm seals for pressure transducers and differential gauges, gaskets, hermetic seals, and thin-film barriers. The continuous strip format allows diaphragm blanks to be stamped efficiently with minimal material waste compared with cutting from flat sheet. The combination of fatigue resistance, dimensional stability under cyclic pressure loading, and non-magnetic behaviour is what drives its selection in precision pressure measurement instruments, particularly those used in magnetically sensitive or corrosive environments.

Havar® coil strip is the source material for X-ray equipment windows in medical, industrial, and analytical systems, and for gap spacers in magnetic recording heads. For X-ray windows, the combination of high strength in thin gauges and low outgassing allows windows to be made thin enough to minimise beam attenuation while maintaining the mechanical integrity needed to seal the X-ray tube vacuum. For recording head gap spacers, the non-magnetic behaviour and long-term dimensional stability under repeated thermal and mechanical cycling are the defining requirements — any magnetic response in the spacer would corrupt the gap geometry and degrade recording performance.

Havar® offers excellent general corrosion resistance through a stable, self-repairing chromia passive layer. Its chemical stability under combined radiation and aqueous exposure has been validated in cyclotron target service. In chloride-containing environments — including physiological fluids, seawater, and certain process chemicals — Elgiloy® and Phynox® offer better pitting and crevice corrosion resistance because of their significantly higher molybdenum content. For industrial, scientific, nuclear, and non-chloride applications, Havar®'s corrosion performance is well suited to extended service life.

Yes. Havar®'s non-magnetic behaviour is intrinsic to its cobalt-chromium matrix and is retained throughout cold rolling, forming, stamping, and age hardening. This distinguishes it from austenitic stainless steels, some of which develop a magnetic response during cold working. Consistent non-magnetic behaviour throughout the supply and processing chain matters in applications where the finished component — whether a spring, diaphragm, or gap spacer — is installed in or near magnetically sensitive equipment.

Precision blanking from cold-rolled coil strip is best performed before age hardening, where the alloy retains sufficient ductility for clean edge formation. Hardened carbide tooling with controlled punch-to-die clearance minimises burr formation and edge cracking. For fully hardened material, laser cutting is the preferred method — offering clean burr-free edges, tight tolerances, and a minimal heat-affected zone. Chemical milling and electrochemical machining are also applicable for complex or delicate geometries where mechanical contact must be avoided, and are particularly relevant for producing thin membranes or microstructured components from strip.

Havar® achieves the highest peak tensile strength of the three alloys, but its minimum bend radius of 8× thickness and 80% cold work requirement before age hardening make it less suited to tight-wound springs and complex coiled geometries than Elgiloy® or Phynox®, which permit 5× bend radii and respond to age hardening after significantly less cold reduction. For watch components, precision instrument springs, cardiovascular coils, and long-term implantable devices, Elgiloy® and Phynox® are the standard specifications. For the highest possible strip strength in power spring, pressure diaphragm, and X-ray window applications, and wherever non-magnetic behaviour and elevated-temperature stability are the critical constraints, Havar® is the correct choice.

Yes. Custom widths, thicknesses, lengths, and spool configurations can be produced with no minimum order quantity. Contact us with your dimensions and required supply condition and we will confirm what is available.

Choose coil when the process requires continuous strip — automated stamping, progressive die operations, spring winding, diaphragm blanking, and roll-to-roll converting all depend on coil to run efficiently and minimise material waste. Foil cut pieces are appropriate for low-volume, non-standard geometry, or single-use applications such as detector windows and hermetic barriers. Disc provides a ready-profiled circular blank for axial mounting applications such as cyclotron target windows and pressure transducer diaphragms where in-house blanking is not practical.