Alloy 20 (CN7M) Products — Alloy 20 (CN7M)

Product Overview

Reviewed and maintained by the Engineering Team, Shaanxi Qianyi Tuoda Technology Co., Ltd.

Alloy 20 (CN7M) Products — Alloy 20 (CN7M) 镍合金产品

If sulfuric acid is your dominant medium, Alloy 20 (UNS N08020, the old CN7M) is the purpose-built nickel-iron-chromium-molybdenum-copper alloy that resists sulfuric across a wide concentration and temperature range better than 316L and without the price of Hastelloy. Its copper and molybdenum defeat sulfuric and phosphoric attack and give good pitting, crevice and stress-corrosion resistance. We stock tube, plate, bar, fittings and flange in Baoji with full MTC. This guide covers what Alloy 20 beats, which ASTM fits each form, where it fails, and how to RFQ it.

The reason a product guide beats a catalogue is simple: the seven nickel families (tube, plate, bar, wire, fittings, flange, fasteners) are not independent. A corrosive line is plate shells, tube bundles, bar-made shafts and fittings from one grade system — specifying them consistently is what keeps a plant leak-free for decades. Below, this alloy gets its own section, then the shared failure map and one selection rule. For the other alloys see our nickel alloy nickel alloy hub.

At a Glance: Alloy 20 (CN7M) Products

1. What Alloy 20 (CN7M) 镍合金产品 Actually Is (and Why Buyers Confuse It)

Alloy 20 (N08020, formerly CN7M) is an iron-nickel-chromium alloy with about 33% nickel, 20% chromium, 3% molybdenum and 3% copper. The copper and molybdenum are the active ingredients against sulfuric and phosphoric acid, while the chromium and nickel give pitting, crevice and stress-corrosion resistance. It is the sulfuric-acid specialist of the nickel-alloy family — we plan tube, fittings and flange from one grade system.

2. Grade Quick-Reference — Alloy 20 (N08020 / CN7M)

For the full nickel-family picture — Inconel, Hastelloy, Monel, Incoloy, Alloy 20 side by side — see our alloy matrix alloy fabrication matrix. If you also run titanium lines, our titanium titanium guide explains where each metal owns the service.

3. How to Read a Alloy 20 (CN7M) Products RFQ

A usable quote starts with a usable request. Put these on the enquiry so we return price and lead time instead of questions:

• Grade — Alloy 20 (N08020 / CN7M).
• Spec — B729 (tube), B463 (plate), B473 (bar), B366 (fittings), B462 (flange).
• Size — OD / thickness / length / diameter, quantity.
• Condition — annealed; tolerance class.
• Ends — plain, bevelled, or forged flange.
• Certificate — EN 10204 3.1 MTC with heat number.
• Service — acid concentration, temperature, contaminants.
• Packing — VCI, crate, port.

4. Alloy 20 (CN7M) Products Forms, Sizes & What to Specify

5. Standard & Certification You Receive

Each lot ships with an EN 10204 3.1 mill test certificate, heat-number traceable to the melt, to ASTM B463/B729/B473 as applicable. Condition is annealed per spec, and PMI or UT can be added on the order. For fabrications we kit the matching fittings and flange from one shipment.

6. The “One Alloy Solves Everything” Myth

Alloy 20 is not a universal acid alloy — hydrochloric acid attacks it, and for very broad or strongly oxidising acid duty you step to Hastelloy C-276 or C-22. It is the sulfuric/phosphoric specialist; for seawater strength, Inconel 625. Match the grade to the actual medium.

7. Where Alloy 20 (CN7M) Products DOES Fail — Limitation & Failure Conditions

Alloy 20 limits centre on its sulfuric-acid design: superb there, weaker in chloride-heavy or strongly oxidising service. Read the shared high-nickel failure map, then the alloy-specific notes.

Two joint-specific notes. Pick the gasket for the actual medium, and avoid coupling the nickel alloy directly to a much nobler metal (graphite, platinum, passive titanium in oxidising service) without isolation — it can become the anode. Where the service is oxidising or mixed acid, step to Hastelloy C-276 or C-22 rather than pushing the alloy past its limit.

8. Choose by Service, Not by Habit

Choose this if:

• Sulfuric acid across a wide range → Alloy 20.
• Phosphoric acid, mixed acid with sulfuric → Alloy 20.
• Pitting/SCC concern in acid → Alloy 20 over 316L.

Choose that if:

• Hydrochloric acid present → Hastelloy C-276 (Alloy 20 is weak in HCl).
• Oxidising or very broad acid → Hastelloy C-22.
• Seawater + strength → Inconel 625.
• Mild duty → 316L stainless is cheaper.

9. Common Procurement Mistakes

• Using Alloy 20 in hydrochloric acid — attack; use Hastelloy.
• Over-specifying Alloy 20 for mild duty — 316L suffices and costs less.
• Wrong filler (ERNiCrMo-3 per procedure).
• No MTC on a pressure part.

10. Lead Time, MOQ & Export Packing

Alloy 20 is held in Baoji across tube, plate, bar, fittings and flange, cut to size and dispatched fast for standard sizes. Heavy-wall tube, large forged flange or special tempers lead a few weeks. Small MOQ applies — a single spool, one plate or a set of flanges is a normal order, and we kit the whole line from one shipment.

11. Alloy vs the Alternatives — When NOT to Specify This Alloy

12. Welding & Joining Note

These nickel alloys weld readily by GTAW / GMAW / SMAW, but the stubborn oxide must be cleaned first or fusion fails, and welding wire must be kept dry to avoid porosity. For this family specify filler ERNiCrMo-3 (often acceptable; confirm per weld procedure); follow a qualified WPS with argon back-purge on tube and pipe, and we supply the matching wire and forming notes so the weld stays in grade. Always confirm the filler matches the base grade on the RFQ.

13. Reading the Mill Test Certificate

Every lot ships with an EN 10204 3.1 EN 10204 3.1 MTC: grade and UNS, heat number, chemistry, tensile result, and the ASTM specification. Keep the heat number — it is your traceability link from the finished part back to the melt, and it is what lets an auditor confirm the grade years later. For project work ask for PMI or UT on the order so the certificate matches the actual piece.

14. Why a Baoji Titanium-Valley Stockist

We hold nickel alloys and titanium together in Baoji Baoji, close to China’s Titanium Valley supply base, which means we can cut, forge and kit a mixed line from one shipment instead of chasing several mills. That shortens lead time from mill-weeks to days and keeps one grade logic, one certificate pack, and one point of contact for your whole order. Our nickel buying guide explains the stock-holder model for overseas buyers.

15. A 5-Minute RFQ Template

Copy this into your enquiry and fill the blanks — it returns a quote, not a guessing game:

• Product: Alloy 20 (CN7M) Products, grade ___
• Spec: ___ (ASTM / ASME)
• Size: ___ ; quantity ___
• Condition / finish: ___
• Certificate: EN 10204 3.1, UT/PMT if needed
• Service: medium ___, concentration ___, temperature ___, pressure ___
• Destination & packing: port ___, VCI / crate

Email it to [email protected] — we confirm stock and pricing within 24 hours, and can kit the whole line from one Baoji shipment so grade and certificate stay consistent end to end.

16. FAQ — Alloy 20 (CN7M) Products

When should I specify Alloy 20?

Specify Alloy 20 when sulfuric or phosphoric acid is the dominant medium; it resists those acids across a wide range better than 316L and at lower cost than Hastelloy.

Does Alloy 20 resist hydrochloric acid?

No — hydrochloric acid attacks Alloy 20. If HCl is present, step to Hastelloy C-276 or C-22 instead.

What ASTM applies to Alloy 20 plate versus tube?

B463 for plate and sheet, B729 for seamless tube (B668 for welded), B473 for bar, B366 for fittings and B462 for forged flange.

Why pick Alloy 20 over Hastelloy for sulfuric?

For straight sulfuric/phosphoric service Alloy 20 is far cheaper than Hastelloy and performs well; reserve Hastelloy for broader or oxidising acid mixtures.

What welding filler for Alloy 20?

ERNiCrMo-3 is commonly used, but confirm against your weld procedure; clean the oxide and keep wire dry.

What certificate comes with the order?

EN 10204 3.1 MTC, heat-number traceable to the melt, to the relevant ASTM grade; PMI/UT on request.

Do you export worldwide?

Yes. Baoji stock to global ports, with VCI protection, crating and full MTC and shipping documents.

Summary: One Rule Beats a Catalogue

If you take one thing from this guide, take this: specify the alloy for the fluid, not just the word “nickel alloy,” and treat every joint as a system. Alloy 20 (CN7M) Products is the right call for its service window — and never specify it where the limitation map says no. Send the checklist above to [email protected] or use the inquiry form — we confirm stock and pricing within 24 hours, and can kit plate, tube, bar, wire, fittings, flange and fasteners for your whole line from one Baoji shipment.