20Mo-6 (UNS N08026) - Sulfuric Acid Super Austenitic Supplier of Bars, Tubes & Plates | Shanghai Hangbo Alloy Group
Date: 2026年8月9日 Categories: News Views: 272
By Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier | ISO 9001:2015 | Est. 2012
Contact: sales@hangboalloy.com | hangbo@nickel-alloy.com | WhatsApp (Lisa): +86 13611656360
Quick Answer: What Is 20Mo-6?
20Mo-6 (UNS N08026 / Alloy 20 Mo-6) is a super austenitic stainless steel with 33% nickel, 23% chromium, and 6% molybdenum that delivers outstanding resistance to sulfuric acid across a wide concentration range PLUS chloride pitting resistance (PREN ~48) -- combining the acid handling of Alloy 20 with the chloride tolerance of the 6% Mo grades. It is the material of choice for sulfuric acid coolers, chemical process piping, and FGD systems handling acid + chloride mixtures. Shanghai Hangbo Alloy Group supplies 20Mo-6 as round bars, seamless tubes, and plates.
Industry Pain Point: Sulfuric acid plant coolers face a dual corrosion problem: the acid side attacks the material chemically while the cooling-water side attacks it pittingly with chlorides. Standard Alloy 20 (3.5% Mo) survives the acid but pits on the water side; 254SMO survives chlorides but struggles with hot concentrated acid. 20Mo-6's 6% molybdenum + 33% nickel + 2% copper chemistry solves both sides simultaneously -- the single best wrought material for acid-cooler tube service.
Key Properties at a Glance
| Property | Value |
|---|---|
| UNS Number | N08026 |
| W.Nr. | 1.4529 equivalent family |
| Density | 8.10 g/cm3 |
| PREN | ~48 |
| Tensile (Ann.) | >= 550 MPa (80 ksi) |
| Yield (Ann.) | >= 240 MPa (35 ksi) |
| Elongation (Ann.) | >= 30% |
| Key Standards | ASTM B463, B468, B464 |
Product Overview
20Mo-6 is the "6% molybdenum" version of the famous Alloy 20 family. While Alloy 20 (UNS N08020) is the traditional sulfuric acid workhorse with 3.5% Mo, 20Mo-6 doubles the molybdenum to 6% and raises nickel to 33% -- transforming the alloy from an acid specialist into a dual-threat material that handles acid AND chlorides.
The alloy's balanced chemistry provides:
- 23% Chromium + 6% Molybdenum: PREN ~48 -- seawater-grade chloride pitting resistance.
- 33% Nickel: SCC immunity, austenite stability, and acid resistance.
- 2% Copper: The Alloy 20 legacy -- sulfuric acid resistance in the 40-80% concentration range.
Shanghai Hangbo Alloy Group supplies 20Mo-6 in bars, seamless tubes, and plates.
Executive Standards
| Product Form | ASTM |
|---|---|
| Plate, Sheet & Strip | ASTM B463 |
| Seamless Tube | ASTM B468 |
| Seamless Pipe | ASTM B464 |
| Bar & Rod | ASTM B472 |
| Welded Pipe | ASTM B464 / B474 |
Chemical Composition (wt.%)
| Element | Min | Max | Role |
|---|---|---|---|
| Ni | 33.0 | 37.2 | Acid resistance; SCC immunity |
| Cr | 22.0 | 26.0 | Passivity; pitting base |
| Mo | 5.0 | 6.7 | Pitting resistance; PREN anchor |
| Cu | 2.0 | 4.0 | Sulfuric acid resistance |
| Fe | Balance | -- | Matrix |
| C | -- | 0.03 | Ultra-low |
| Mn | -- | 1.0 | Deoxidizer |
| Si | -- | 0.50 | Deoxidizer |
| S | -- | 0.03 | Impurity |
Mechanical & Physical Properties
Room-Temperature (Solution-Annealed 1120C/WQ)
| Property | Value |
|---|---|
| Tensile Strength | >= 550 MPa (80 ksi) |
| Yield Strength 0.2% | >= 240 MPa (35 ksi) |
| Elongation | >= 30% |
| Hardness | <= 90 HRB |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.10 g/cm3 |
| Thermal Conductivity | ~11 W/m-K |
| Magnetic | Non-magnetic |
Heat Treatment
Solution Annealing: 1120C (2050F), water quench mandatory. No precipitation hardening.
Corrosion Performance
| Environment | 20Mo-6 | Alloy 20 |
|---|---|---|
| 40% H₂SO₄, 60C | <0.1 mm/yr | <0.1 mm/yr |
| 50% H₂SO₄, boiling | <0.1 mm/yr | 0.2-0.5 mm/yr |
| Seawater CPT | >= 55C | < 25C |
| 3% NaCl + acid | Resistant | Pitting |
Industry Applications
| Industry | Component | Why 20Mo-6? |
|---|---|---|
| Sulfuric Acid | Cooler tubes, acid piping | Acid + water-side chloride dual resistance |
| Chemical Processing | Reactor internals, heat exchangers | Broad acid/chloride envelope |
| FGD | Absorber quench zones | Condensing acid + chlorides |
| Petrochemical | Alkylation acid handling | HF/H₂SO₄ service |
Quality Assurance: 7-Stage
- Raw Material: Ni, Cr, Mo, Cu verified by OES.
- Melt: Mo +/-0.2%, Cu +/-0.2%, C <=0.02% internal.
- Hot Working: 1150-1200C, finishing >=1000C, reduction >=4:1.
- Solution Anneal: 1120C, WQ. Hardness <=90 HRB.
- Corrosion Test: ASTM G48 Method A + boiling H₂SO₄ per lot on request.
- NDE: 100% UT bars >=50mm; ET/hydro tubes. PMI every piece.
- Documentation: EN 10204 3.1 MTC. SGS/TUV/BV witness.
Frequently Asked Questions
Q1: What is 20Mo-6 used for?
Sulfuric acid cooler tubes, chemical process piping, FGD systems, and any acid + chloride combination environment.
Q2: 20Mo-6 vs Alloy 20?
20Mo-6: 6% Mo, PREN 48, seawater pitting resistance. Alloy 20: 3.5% Mo, PREN 27, acid-only. 20Mo-6 is the upgrade for acid + chloride service.
Q3: 20Mo-6 vs 254SMO?
Similar PREN (~48 vs 43). 20Mo-6's copper provides better sulfuric acid resistance; 254SMO has higher N for strength. Choose 20Mo-6 for acid-dominated, 254SMO for chloride-dominated.
Q4: Is it weldable?
Yes, with ERNiCrMo-3 (625) or matching filler.
Q5: What is the price?
$30-50/kg EXW. Contact sales@hangboalloy.com.
Q6: Product forms?
Bars (6-250mm), tubes (OD 10-219mm), plates (3-50mm). SGS available.
Q7: What heat treatment?
Solution annealing at 1120°C, water quench.
Q8: Is it magnetic?
No -- fully austenitic.
Q9: What is the density?
8.10 g/cm3.
Q10: Does Shanghai Hangbo ship internationally?
Yes -- FOB/CIF/DAP to 40+ countries.
Q11: What standards apply?
ASTM B463 (plate), B468 (tube), B464 (pipe), B472 (bar).
Q12: Can it replace C-276 in acid coolers?
For most H₂SO₄ cooler duty, 20Mo-6 delivers equivalent performance at 40-60% of C-276's cost.
Q13: What is the max service temperature?
~400C continuous.
Q14: Why copper?
Copper provides the Alloy 20 family's sulfuric acid resistance in the mid-concentration range.
Q15: Is NACE MR0175 applicable?
Not the primary qualification; G-50 or 27-7MO are the sour-service choices.
Contact Shanghai Hangbo Alloy Group
| Channel | Details |
|---|---|
| Company | Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier |
| Website | www.nickel-alloy.com |
| Email (Sales) | sales@hangboalloy.com |
| Email (Technical) | hangbo@nickel-alloy.com |
| WhatsApp (Lisa) | +86 13611656360 |
| Address | Room 1508, No. 288 Shiyi Road, Baoshan District, Shanghai 200940, China |
Shanghai Hangbo Alloy Group - Complete Product Range
| Family | Available Grades |
|---|---|
| Pure Nickel | NI200, NI201, N4, N5, N6 |
| Monel | 400, 401, 404, K-500, R-405 |
| Inconel | 600, 601, 617, 625, 690, 693, 718, X-750, 725 |
| Incoloy | 800, 800H, 800HT, 825, 925, 926, 945, A-286, 25-6HN, 27-7MO |
| Hastelloy | C-276, C-22, C-2000, C-4, G-30, G-35, G-50, X, B-2, B-3, B-4, N |
| Super Austenitic | 904L, Alloy 28, Alloy 31, 254SMO, 20Mo-6 |
| Chromium-Rich | Alloy 33 |
| High-Strength Stainless | Nitronic 50, PH13-8Mo |
| Chlorination-Resistant | Alloy 45 |
| Nimonic | 75, 80A, 90, 95, 105, 115, 263 |
| Haynes | 25, 188, 214, 230, 242, 282, 556, HR-120, HR-160 |
| RA Series | RA330, RA333 |
| Precision | 1J22, 1J46, 1J50, 1J79, 1J85, 3J21, 4J32, 4J36, 4J45 |
| High-Strength | 18Ni250, 18Ni300, AerMet 100 |
| Heating | Cr20Ni80, Cr40Ni60 |
| Specialty | Alloy 20, Alloy 59, Inconel 686, 602CA |
Product Forms: Bars(6-500mm) | Tubes(OD 6-610mm) | Plates(0.1-100mm) | Forgings | Welded Pipes | Fittings | Wire(0.05-10mm) | Strip(0.02-4.0mm)
SGS/BV/TUV. Contact: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
