Hastelloy B-2 vs B-3 - Full Comparison for HCl & Reducing Acid Service
Date: 2026年9月2日 Categories: News Views: 290
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 the Difference Between Hastelloy B-2 and B-3?
Hastelloy B-2 (UNS N10665) and Hastelloy B-3 (UNS N10675) are nickel-molybdenum alloys for hot hydrochloric acid and other reducing acids. B-3 was developed to fix B-2's fatal flaw: B-2 is prone to intermetallic phase precipitation (Ni-Mo compounds) in the heat-affected zone during welding, which destroys ductility and causes cracking. B-3's optimized chemistry (controlled Fe, Cr, W additions) makes it thermally stable during welding and fabrication — usable in the as-welded condition without the risk of HAZ embrittlement. For new HCl equipment, B-3 is the safe, modern choice; B-2 is the legacy alloy.
Composition Comparison (wt.%)
| Element | B-2 (N10665) | B-3 (N10675) |
|---|---|---|
| Nickel | Balance | Balance |
| Molybdenum | 26-30 | 27-32 |
| Iron | 2 max | 1.5-4.5 |
| Chromium | 1 max | 1-3 |
| Tungsten | -- | 3 max |
| Cobalt | 1 max | 3 max |
| Carbon | 0.01 max | 0.01 max |
Key Difference: Thermal Stability
| Property | B-2 | B-3 |
|---|---|---|
| HAZ precipitation during welding | High risk | Very low |
| As-welded usability | Requires care/PWHT | Yes, as-welded |
| Ductility after welding | Can embrittle | Stable |
| Fabrication complexity | High | Low |
| Typical use | Legacy replacement parts | New equipment |
Corrosion Performance Comparison
| Environment | B-2 | B-3 |
|---|---|---|
| Hot HCl (all concentrations) | Excellent | Excellent |
| H2SO4 (reducing) | Excellent | Excellent |
| H3PO4 (crude) | Excellent | Excellent |
| Acetic acid + reducing | Excellent | Excellent |
| Oxidizing media | Poor | Poor (avoid) |
Corrosion resistance is equivalent — B-3's advantage is purely fabricability.
Mechanical Properties (Annealed)
| Property | B-2 | B-3 |
|---|---|---|
| Tensile | >= 690 MPa | >= 690 MPa |
| Yield | >= 310 MPa | >= 310 MPa |
| Elongation | >= 40% | >= 40% |
Price Comparison (2026, EXW)
| Form | B-2 | B-3 |
|---|---|---|
| Round Bar | \$60-95/kg | \$62-98/kg |
| Plate | \$62-98/kg | \$65-100/kg |
| Tube | \$75-115/kg | \$78-120/kg |
B-3 costs 3-5% more — a small premium for weldability insurance.
FAQ
Q1: Is B-3 better than B-2?
For new welded equipment, yes — B-3 is thermally stable during welding, avoiding B-2's HAZ cracking risk.
Q2: What is the main problem with B-2?
Ni-Mo intermetallic precipitation in the weld heat-affected zone can embrittle the material.
Q3: Can B-3 replace B-2?
Yes, in virtually all reducing-acid service. Check oxidizing contaminants first.
Q4: What are the UNS numbers?
N10665 = B-2; N10675 = B-3.
Q5: Which is more expensive?
B-3 is 3-5% more expensive.
Q6: Are they suitable for oxidizing media?
No — both are strictly for reducing acids; oxidizing media destroys them.
Q7: What does Shanghai Hangbo supply?
Both grades in bars, plates, sheets, and tubes with EN 10204 3.1 certification. SGS/TUV/BV available.
Contact & Complete Product Range
Shanghai Hangbo Alloy Group Co., Ltd. - China Supplier
Email: sales@hangboalloy.com | WhatsApp (Lisa): +86 13611656360 | www.nickel-alloy.com
All Grades
Ni: NI200-N6 | Monel: 400-502, K-500, R-405 | Inconel: 600-740H, X-750, 725 | Incoloy: 800-27-7MO | Hastelloy: C-276-HYBRID-BC1, N | Super Austenitic: 904L-AL-6XN | Chromium-Rich: Alloy 33 | High-Strength Stainless: Nitronic 50/60, PH13-8Mo | Chlorination: Alloy 45 | Nimonic: 75-263 | Haynes: 25-HR-160 | RA: 330/333 | Precision: 1J22-4J45 | High-Strength: 18Ni250-AerMet100 | Heating: Cr20Ni80/60 | Specialty: Alloy 20-602CA
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)
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