Alloy 600

Identity and purchase description

VDM prefers its solution-annealed Alloy 600 H above 700°C because of improved creep resistance. Its July 2021 sheet also warns of selective oxidation (green rot) under alternating oxidizing and reducing conditions. Use the actual atmosphere, load and time at temperature to assess service. VDM 600 and 600 H application guidance

Alloy 600 is a nickel-chromium-iron alloy identified as UNS N06600 / material number 2.4816. INCONEL is a Special Metals trademark; VDM Alloy 600 is another producer's product name. A generic designation does not establish who manufactured the delivered material. Special Metals SMC-027, VDM product identity

Special Metals gives limiting composition, by mass, as nickel plus cobalt ≥72%, chromium 14–17%, iron 6–10% and carbon ≤0.15%, with additional limits on minor elements. It describes strengthening by cold work rather than precipitation hardening. Consequently, the name alone cannot establish the strength of a particular bar, sheet or tube. Special Metals composition and condition

Properties: condition and test basis first

VDM's July 2021 sheet separates annealed Alloy 600 from solution-annealed Alloy 600 H. Its Table 4a lists annealed Alloy 600 minima at 20°C of 200 MPa Rp0.2, 550 MPa tensile strength and 30% elongation, referring to VdTÜV material sheet 305. The text restricts applicability to specified semi-finished forms and dimensions and requires separate agreement for larger dimensions. Table 4b gives different values for 600 H. Do not combine the strongest entries from these rows into an invented material condition. VDM Tables 4a–4b

Special Metals explicitly labels its property data as typical unless identified as minima or maxima. Representative physical values include density 8.47 Mg/m³ and Young's modulus 214 GPa at 22°C. Neither is an inspection acceptance limit. Special Metals Tables 2 and 4

Heat and corrosion service are environment-specific

VDM describes furnace components, chemical-process equipment and high-temperature sensors as applications. Its product page lists resistance to oxidation, carburization and nitriding, and to dry chlorine and hydrogen chloride. These descriptions are screening information: they do not establish compatibility with wet process mixtures or all concentrations and temperatures. VDM application and resistance overview

VDM identifies green rot as selective oxidation under changing atmosphere conditions. VDM corrosion and application section

For aqueous exposure, record the complete chemistry, temperature, aeration, contaminants, flow, deposits and stress state. The distinction between dry and wet gas is especially important when a process can cross its condensation point during startup or shutdown. Evaluate those transients alongside steady operation.

Chloride stress-corrosion resistance does not mean immunity to every stress-corrosion mechanism. NRC documents primary-water stress-corrosion cracking of Alloy 600 components and associated Alloy 82/182 weld materials in pressurized-water reactors. Its overview identifies a strong temperature dependence and notes replacements using less susceptible Alloy 690 and Alloy 52/152 weld materials. Those reactor findings must not be generalized into a corrosion rate for an unrelated process, but they rule out a blanket claim of SCC immunity. NRC reactor pressure-boundary overview

PNNL's 2017 study of three mill-annealed heats in simulated reactor primary water found that a small amount of cold work greatly reduced crack-initiation times. This is evidence that material history matters in that environment, not a universal cold-work rejection threshold. PNNL study summary, published 27 April 2017

Fabrication and joining

VDM requires clean workpieces before and during heat treatment and identifies sulfur, phosphorus, lead and other low-melting metals as damaging contaminants; marking materials, oils and grease can introduce them. Its welding guidance advises avoiding flame straightening because of unwanted structural changes. VDM heating and post-weld guidance

The process plan should therefore identify cleaning materials, tooling contact, heat-treatment condition and final surface requirements. Record any cold reduction, forming or local heating that changes the supplied condition. Qualify welding against the actual joint and service requirement, including filler selection, dilution, heat input and any required post-treatment. Matching a base-metal designation is insufficient to choose a consumable for every dissimilar joint or corrosive service.

For machining, establish parameters using the actual stock condition and cutting operation. Annealed and heavily cold-worked stock should not inherit one unqualified speed/feed recipe. Inspect the finished surface and dimensions against the drawing, and retain the connection between the component and its material certificate.

Bounded estimating example

Using Special Metals' typical density, an ideal solid blank measuring 100 × 50 × 10 mm has volume 50,000 mm³ = 50 cm³. Since 8.47 Mg/m³ equals 8.47 g/cm³, estimated mass is 423.5 g. This is original arithmetic for a rectangular blank: it excludes dimensional tolerances, holes and machining allowance. It is useful for an initial mass estimate, not a weighing acceptance criterion or structural calculation.

A useful material record would store that estimate separately from the delivered mass, certificate properties and approved service assessment. The distinction prevents a calculated catalogue-based number from acquiring the status of a measured result.

Source versions and related reference

Special Metals identifies its bulletin as SMC-027, September 2008 on page 1. The VDM technical sheet carries July 2021 in its page headers. The PNNL summary was published in 2017 and shows a 2020 revision date. These are source dates, distinct from this draft's review date; verify current order and design-code requirements before procurement.

Grades, tempers and conditions