⚡ Quick Specs: Hastelloy G-35
What Is Hastelloy G-35?
Hastelloy G-35 (UNS N06035 / W.Nr. 2.4643) is a nickel-chromium-molybdenum alloy specifically engineered for wet process phosphoric acid service in the fertilizer industry. With an exceptionally high chromium content of 33%, it offers best-in-class resistance to oxidizing acids and chloride-induced pitting — outperforming all other G-series alloys in phosphoric acid and mixed acid environments. As a trusted Hastelloy G-35 supplier and manufacturer, Hangbo Alloy Group provides this premium alloy in all standard product forms with full mill certification.
Chemical Composition
The nominal chemical composition of Hastelloy G-35 is shown below. All values are in weight percent (wt%) unless otherwise noted.
| Element | Content (wt%) |
|---|---|
| C | ≤ 0.05 |
| Si | ≤ 0.60 |
| Mn | ≤ 0.50 |
| P | ≤ 0.03 |
| S | ≤ 0.015 |
| Cr | 32.25–34.25 |
| Ni | Balance |
| Co | ≤ 1.00 |
| Mo | 7.6–9.0 |
| W | ≤ 0.60 |
| Al | ≤ 0.40 |
| Cu | ≤ 0.30 |
| V | ≤ 0.20 |
| Fe | ≤ 2.0 |
Physical Properties
| Property | Value |
|---|---|
| Density | 8.22 g/cm³ (0.297 lb/in³) |
| Melting Range | 1332–1361 °C (2430–2482 °F) |
| Specific Heat | ~430 J/kg·K |
| Thermal Conductivity | ~10.1 W/m·K (at 20°C) |
| Electrical Resistivity | ~1.18 µΩ·m (at 20°C) |
| Young's Modulus | ~200 GPa |
Mechanical Properties (Room Temperature)
| Property | Value |
|---|---|
| Tensile Strength (Rm) | ≥ 710 MPa |
| Yield Strength (Rp0.2) | ≥ 317 MPa |
| Elongation (A%) | ≥ 66% |
| Hardness | ≤ 100 HRB |
| Condition | Solution Annealed |
Exceptional Corrosion Resistance — Wet Process Phosphoric Acid & Beyond
Hastelloy G-35 delivers best-in-class corrosion resistance in wet process phosphoric acid — the exact environment that drove its development. The alloy's 33% chromium content provides exceptional resistance to oxidizing acids including nitric acid, while its 8% molybdenum content ensures resistance to reducing acids and chloride-induced pitting.
- Immune to chloride-induced stress corrosion cracking (SCC) — a critical advantage over austenitic stainless steels like 316L and 904L
- Outstanding resistance to pitting and crevice corrosion in chloride-containing phosphoric acid — PREN (Pitting Resistance Equivalent Number) exceeds 50
- Excellent performance in mixed acid environments containing H₃PO₄ + H₂SO₄ + HF, common in fertilizer production
- Superior to Hastelloy G-30 in oxidizing acid conditions due to higher chromium content
- Resistant to nitric acid at concentrations up to 65% at elevated temperatures
Applications
Hastelloy G-35 was specifically developed to overcome the corrosion limitations of earlier G-series alloys in wet process phosphoric acid environments. The alloy's exceptionally high chromium content and balanced molybdenum addition provide a unique combination of oxidizing and reducing acid resistance.
| Application Area | Typical Components & Notes |
|---|---|
| Fertilizer Manufacturing | Evaporators, heat exchangers, pipes, and reaction vessels handling wet process phosphoric acid (P₂O₅) — the alloy's primary design target |
| Chemical Processing | Reactors, columns, and piping for mixed acid environments containing sulfuric, phosphoric, and nitric acids |
| Pollution Control | Flue gas desulfurization (FGD) scrubbers, chimney liners, and ducting exposed to acid condensates |
| Nuclear Industry | Nuclear fuel reprocessing equipment where mixed nitric-hydrofluoric acid resistance is required |
| Gold Mining / Ore Processing | Pressure oxidation autoclaves and acid leach tanks handling hot sulfuric-phosphoric mixtures |
| Pesticide Manufacturing | Reaction and storage vessels for organophosphate and chlorinated pesticide synthesis |
| Marine Engineering | Seawater-cooled heat exchangers and offshore platform piping systems |
Available Product Forms
| Product Form | Typical Dimensions |
|---|---|
| Round Bars (ASTM B574) | φ6–φ300 mm, Hot-rolled, Cold-drawn, Forged |
| Plates & Sheets (ASTM B575) | Thickness 0.5–80 mm, Width up to 2500 mm |
| Seamless Tubes (ASTM B622) | OD 6–219 mm, WT 0.5–20 mm |
| Welded Pipes (ASTM B619/B775) | OD 10–1219 mm, WT 1.0–20 mm |
| Fittings (ASTM B366) | Elbows, Tees, Reducers, Caps — Butt-weld & Socket-weld |
| Forgings (ASTM B564) | Discs, Rings, Shafts, Custom shapes |
| Welding Wire | ERNiCrMo-22 filler metal |
Related Standards & Specifications
| Standard | Product Scope |
|---|---|
| ASTM B574 | Rod & Bar |
| ASTM B575 | Plate, Sheet & Strip |
| ASTM B622 | Seamless Pipe & Tube |
| ASTM B619 / B775 | Welded Pipe |
| ASTM B626 / B751 | Welded Tube |
| ASTM B366 | Fittings |
| ASTM B564 | Forgings |
| ASME SB-574 / SB-575 / SB-622 | Pressure Vessel Applications |
| NACE MR0175 / ISO 15156 | Sour Service (H₂S containing environments) |
| EN / DIN W.Nr. | 2.4643 |
Frequently Asked Questions (FAQ)
1. What is Hastelloy G-35 alloy?
Hastelloy G-35 (UNS N06035 / W.Nr. 2.4643) is a nickel-chromium-molybdenum alloy specifically developed for wet process phosphoric acid environments. With a unique 33% chromium content — the highest in the G-series family — it provides exceptional resistance to oxidizing acids while maintaining good resistance to reducing acids. It is the material of choice for evaporators, heat exchangers, and piping in fertilizer-grade phosphoric acid production.
2. What is the chemical composition of Hastelloy G-35?
Hastelloy G-35 nominal composition: Ni balance, Cr 32.25–34.25%, Mo 7.6–9.0%, Fe ≤2.0%, Co ≤1.0%, W ≤0.60%, Mn ≤0.50%, Si ≤0.60%, Al ≤0.40%, Cu ≤0.30%, V ≤0.20%, C ≤0.05%, P ≤0.03%, S ≤0.015%. The exceptionally high chromium content (33%) distinguishes it from other G-series alloys and provides outstanding oxidizing acid resistance.
3. What is the density and melting point of Hastelloy G-35?
Hastelloy G-35 has a density of 8.22 g/cm³ (0.297 lb/in³) and a melting range of 1332–1361 °C (2430–2482 °F). Its density is slightly lower than many nickel-based alloys due to the high chromium content, which can be an advantage in weight-sensitive applications.
4. What are the mechanical properties of Hastelloy G-35?
Typical solution-annealed mechanical properties: tensile strength ≥710 MPa (103 ksi), yield strength (0.2% offset) ≥317 MPa (46 ksi), elongation ≥66%, hardness ≤100 HRB. The alloy maintains excellent ductility even after extended high-temperature exposure, making it suitable for forming and fabrication.
5. What is the maximum service temperature of Hastelloy G-35?
Hastelloy G-35 is typically used up to approximately 600 °C (1112 °F) in corrosive chemical environments. While its mechanical strength is maintained at higher temperatures, prolonged exposure above 650 °C may lead to microstructural changes that can affect corrosion resistance. For purely high-temperature structural applications above 600 °C, alternatives like Inconel 625 or Haynes 230 are generally recommended.
6. How does Hastelloy G-35 compare to Hastelloy G-30?
Hastelloy G-35 was developed as an improvement over G-30 specifically for wet process phosphoric acid. The key difference is chromium content: G-35 contains 33% Cr vs. 28-31.5% in G-30. This higher chromium level provides superior resistance to oxidizing acids (especially nitric acid) and better chloride pitting resistance. G-35 also offers improved corrosion resistance in mixed acid environments containing H₃PO₄ + H₂SO₄ + HF. For most phosphoric acid applications, G-35 is the preferred choice over G-30.
7. Can Hastelloy G-35 be welded?
Yes, Hastelloy G-35 has excellent weldability using GTAW (TIG), GMAW (MIG), and SMAW processes. Recommended filler metals include ERNiCrMo-22 for TIG/MIG and ENiCrMo-22 for SMAW. The alloy does not require post-weld heat treatment for corrosion resistance in most applications. Standard welding procedures for nickel-based alloys should be followed: clean base metal, low interpass temperature (<120°C), and minimal heat input.
8. What standards apply to Hastelloy G-35?
Key standards: ASTM B574 (rod & bar), ASTM B575 (plate/sheet/strip), ASTM B622 (seamless pipe & tube), ASTM B619/B775 (welded pipe), ASTM B626/B751 (welded tube), ASTM B366 (fittings), ASTM B564 (forgings), and corresponding ASME SB standards for pressure vessel applications. The alloy is also covered under NACE MR0175/ISO 15156 for sour service applications.
9. What are the typical applications of Hastelloy G-35?
Primary applications: (1) Fertilizer manufacturing — evaporators, heat exchangers, and piping for wet process phosphoric acid; (2) Chemical processing — mixed acid environments; (3) Gold mining — pressure oxidation autoclaves; (4) Nuclear — fuel reprocessing equipment; (5) Pesticide manufacturing; (6) FGD scrubbers in pollution control; (7) Marine/offshore — seawater-cooled equipment.
10. What is the price and lead time for Hastelloy G-35?
Hastelloy G-35 is a premium specialty alloy. Typical pricing: bars $40-60/kg, plates $50-80/kg, seamless tubes $70-120/kg, depending on size, quantity, and market conditions. Lead times are typically 8-14 weeks for mill orders. Hangbo Alloy maintains strategic inventory of common sizes for expedited delivery. MOQ: 50-100 kg for stock sizes, 200-500 kg for custom specifications. Contact hangbo@nickel-alloy.com for current pricing and availability.
11. How does Hastelloy G-35 resist chloride pitting?
Hastelloy G-35 resists chloride pitting through its exceptionally high chromium (33%) and molybdenum (8%) content. The Pitting Resistance Equivalent Number (PREN = %Cr + 3.3×%Mo) exceeds 50, placing it among the most chloride-resistant nickel alloys available. This high PREN value means G-35 can withstand chloride concentrations that would cause rapid pitting in 316L stainless steel (PREN ~24) and even 6Mo super-austenitic steels (PREN ~43).
12. Can Hastelloy G-35 be used in sulfuric acid?
Yes, Hastelloy G-35 offers moderate resistance to sulfuric acid across a range of concentrations and temperatures, but its performance is optimized for oxidizing conditions. It performs best in sulfuric acid with oxidizers present (e.g., mixed H₂SO₄ + HNO₃ or H₂SO₄ + H₃PO₄). In pure reducing sulfuric acid at high concentrations (>70%) and elevated temperatures (>80°C), Hastelloy B-3 or C-276 may be more suitable alternatives. Contact our engineers for specific process condition recommendations.
Need Hastelloy G-35 for Your Project?
Hangbo Alloy Group is a trusted global supplier of Hastelloy G-35 in bars, plates, and custom forms. We provide competitive pricing, full material traceability, and EN 10204 3.1 mill test certificates with every order.