ZIRCONIUM &

ZIRCONIUM Alloys

Zirconium 700 is the low-oxygen commercially pure zirconium grade used when Zr 702-level corrosion resistance is needed with improved ductility, toughness, or formability. By limiting oxygen content to 0.10% maximum, Zr 700 is better suited for applications involving severe forming, cladding, and explosion bonding, where material toughness and deformation behavior are critical.

Where Zr 700 is typically selected for lower-oxygen formability and cladding applications, Zr 702 remains the standard workhorse grade for broad chemical-processing fabrication.

Zirconium 702 — commercially pure zirconium (minimum 99.2% Zr+Hf, hafnium up to 4.5%) in wrought sheet, plate, rod, bar, and tube form — is the workhorse industrial zirconium grade for chemical processing equipment in corrosive acid service. Zirconium's corrosion resistance derives from a self-renewing, tightly adherent ZrO₂ oxide film that provides exceptional protection against virtually all mineral and organic acids: it resists hydrochloric acid at all concentrations and temperatures, sulfuric acid up to 70% at boiling and higher concentrations at lower temperatures, nitric acid, phosphoric acid, and hydrofluoric acid in dilute concentrations — performing in environments where even titanium Grade 2, Hastelloy C-276, and tantalum may be marginal or require review. This makes Zr 702 the standard specification in the fine chemical, pharmaceutical, and specialty chemical industries for heat exchangers, reactor vessel liners, distillation column components, bayonet heaters, and piping systems processing corrosive intermediates and reagents. It is listed in the ASME Boiler and Pressure Vessel Code for unfired pressure vessels, enabling its use in regulated chemical pressure equipment. Surplus Zr 702 from decommissioned chemical plant equipment, changed process specifications, and fabrication shop overruns has consistent buyer demand among chemical equipment fabricators and specialty metal distributors.

Zirconium 705 — alloyed with 2–3% niobium — delivers significantly higher mechanical strength than commercially pure Zr 702 while retaining the same exceptional acid corrosion resistance. With a minimum tensile strength of 552 MPa (vs. 380 MPa for Zr 702) and minimum yield strength of 379 MPa, Zr 705 is the specification for chemical process equipment in more mechanically demanding service: higher-pressure reactors and heat exchangers, structural components where wall-thickness reduction is economically significant, and large-diameter pressure vessels where the higher strength-to-weight ratio of Zr 705 justifies its premium over Zr 702. Zr 705 requires stress relief heat treatment within 14 days of welding — a fabrication requirement that must be communicated to buyers. The alloy is also used in defense and aerospace applications where zirconium's corrosion resistance must be combined with structural load-bearing capability. In the nuclear industry, Zr-Nb alloys (in various Nb contents) underpin the advanced CANDU pressure tube specification (Zr-2.5Nb) and have influenced the development of proprietary Zr-Nb cladding alloys (ZIRLO, M5) now standard in modern PWR fuel designs.

Zirconium sponge — the primary metallic form produced by the Kroll process (reduction of zirconium tetrachloride with magnesium in a sealed reactor vessel, followed by vacuum distillation to remove magnesium and magnesium chloride) — is the foundational raw material for all downstream zirconium metal products. Nuclear-grade sponge (hafnium below 100 ppm) is the starting point for all Zircaloy and advanced nuclear alloy production. Commercial-grade sponge (hafnium up to 4.5%) is the feedstock for Zr 702/705 wrought products and zirconium chemicals. The sponge appears as a porous, gray metallic mass and is crushed, blended with alloy additions, and consolidated by vacuum arc remelting (VAR) into ingots before further processing into wrought mill products. Surplus nuclear-grade sponge from changed fuel specifications, production overruns, and qualification lot failures has a narrow but active buyer base among nuclear fuel fabricators. Commercial-grade sponge surplus finds buyers among Zr 702/705 wrought product producers and zirconium chemical manufacturers. Hafnium content, oxygen content, and chloride residual are the critical analytical parameters that determine grade, buyer eligibility, and pricing. Low-oxygen sponge or feedstock may be relevant for Zr 700 production, where the finished product must meet the tighter R60700 oxygen limit.