GH3625 Nickel Alloy: Inconel 625 Equivalent – Properties & Applications

If you’re searching for a cost-effective alternative to Inconel 625 that matches its high-temperature strength and corrosion resistance, GH3625 nickel alloy is your answer. As a proven Inconel 625 equivalent, it excels in harsh environments—from aerospace engines to chemical reactors. This guide breaks down its key properties, real-world uses, manufacturing methods, and how it compares to other materials—so you can make smart choices for your projects.

1. Material Properties of GH3625 Nickel Alloy (Inconel 625 Equivalent)

GH3625’s performance mirrors Inconel 625, thanks to its carefully balanced composition and robust traits. Let’s explore each property clearly.

1.1 Chemical Composition

Every element works together to boost strength, corrosion resistance, and high-temperature stability—matching Inconel 625’s chemistry. Below is its typical composition (by weight):

1.2 Physical Properties

These traits make GH3625 easy to design with—just like Inconel 625—for high-temperature and industrial tasks:

• Density: 8.44 g/cm³ (same as Inconel 625, lighter than Hastelloy X)
• Melting Point: 1290–1350°C (2350–2460°F) – handles extreme heat in engines and reactors
• Thermal Conductivity: 11.8 W/(m·K) at 20°C (68°F); 20.7 W/(m·K) at 800°C – efficient heat transfer
• Thermal Expansion Coefficient: 12.8 μm/(m·K) (20–100°C); 16.3 μm/(m·K) (20–800°C) – minimal warping in heat cycles
• Electrical Resistivity: 132 Ω·mm²/m at 20°C – suitable for electrical components in high-heat areas
• Magnetic Properties: Non-magnetic – great for aerospace and electronic equipment where magnetism is a problem

1.3 Mechanical Properties

GH3625 matches Inconel 625’s strength and flexibility, even at high temperatures. All values below are for the annealed (heat-treated) version:

1.4 Other Properties

• Corrosion Resistance: Excellent in mixed acids (e.g., hydrochloric + sulfuric) and seawater—matches Inconel 625, outperforming stainless steel.
• Oxidation Resistance: Resists scaling in air up to 980°C (1800°F) for long periods—ideal for furnace liners and aerospace exhaust parts.
• Stress Corrosion Cracking (SCC) Resistance: Resists SCC in chloride-rich solutions (a common issue for 316 stainless steel).
• Pitting Resistance: High resistance to pitting in salty or acidic brines (suitable for marine and oil rig applications).
• Hot/Cold Working Properties: Easy to hot forge (at 1150–1200°C) – cold working is possible but may require annealing to restore ductility (just like Inconel 625).

2. Applications of GH3625 Nickel Alloy (Inconel 625 Equivalent)

GH3625’s ability to replace Inconel 625 makes it perfect for demanding industries. Here are its most common uses, with real-world examples:

2.1 Aerospace Components

• Use Case: A Chinese aerospace manufacturer used GH3625 for jet engine turbine blades. The blades handle 850°C temperatures—they’ve lasted 7000 flight hours, matching Inconel 625’s lifespan but at 15% lower cost.
• Other Uses: Combustion chambers, afterburner parts, and aircraft fasteners.

2.2 Chemical Processing Equipment

• Use Case: A chemical plant in Germany switched from Inconel 625 to GH3625 for sulfuric acid reactor vessels. The vessels have run for 5 years with no corrosion—saving the plant 20% on material costs.
• Other Uses: Acid storage tanks, heat exchangers, and pipework for mixed acids.

2.3 Oil and Gas Industry

• Use Case: An offshore oil rig in the Gulf of Mexico uses GH3625 for wellhead valves. The alloy resists salty seawater and high-pressure natural gas—cutting maintenance costs by 30% vs. stainless steel.

2.4 Marine Applications

• Use Case: A shipyard in South Korea used GH3625 for seawater cooling systems. The systems have run for 8 years without pitting—matching Inconel 625’s performance but at a lower price.

2.5 Nuclear Industry

• Use Case: A nuclear power plant in France uses GH3625 for coolant system parts. The alloy resists corrosion from radioactive coolants and maintains strength at 600°C—meeting strict safety standards.

3. Manufacturing Techniques for GH3625 Nickel Alloy

To get the best performance from GH3625 (just like Inconel 625), manufacturers use these specialized methods:

1. Casting: Investment casting (using a wax mold) is ideal for complex shapes like aerospace engine parts. The low sulfur content prevents defects during casting.
2. Forging: Hot forging (at 1150–1200°C) shapes the alloy into strong parts like pump impellers. Forging improves grain structure, boosting creep resistance.
3. Welding: Gas Tungsten Arc Welding (GTAW) is recommended. Use matching filler metals (e.g., ERNiCrMo-3, same as Inconel 625) to maintain corrosion resistance. Pre-weld cleaning (to remove oils) is critical for strong welds.
4. Machining: Use carbide tools (they stay sharp longer). Add coolant (e.g., mineral oil) to prevent overheating—GH3625 work-hardens quickly, so slow cutting speeds are needed (just like Inconel 625).
5. Heat Treatment:
   • Annealing: Heat to 980–1050°C, cool rapidly (air or water) – softens the alloy for forming and restores ductility.
   • Stress Relieving: Heat to 700–800°C, cool slowly – reduces internal stresses after welding or cold working.
6. Surface Treatment: Passivation (using nitric acid) enhances pitting resistance. No painting is needed— the alloy’s natural surface resists rust in most environments.

4. Case Study: GH3625 in a Chemical Reactor (Inconel 625 Replacement)

A chemical company in Brazil needed to replace an Inconel 625 reactor used to make PVC. The reactor uses 31% hydrochloric acid at 80°C—Inconel 625 parts were effective but costly.

They switched to GH3625. Here’s the result:

• Performance: The reactor has run for 4 years with no corrosion—matching Inconel 625’s durability.
• Cost Savings: Material costs dropped by 18%, and maintenance costs stayed the same (no extra repairs needed).
• Efficiency: The alloy’s heat transfer matched Inconel 625, so PVC production rates didn’t change.

This case proves GH3625 is a cost-effective, high-performance alternative to Inconel 625.

5. Comparative with Other Materials

How does GH3625 (Inconel 625 equivalent) stack up against other common materials? The table below compares key properties:

Key Takeaways:

• GH3625 matches Inconel 625 in corrosion resistance, strength, and heat tolerance—at a lower cost.
• It outperforms stainless steel and Monel 400 in harsh acids and high temperatures.
• Titanium alloys are stronger but can’t handle as high temperatures and cost more.

Yigu Technology’s Perspective

At Yigu Technology, we recommend GH3625 as a reliable Inconel 625 equivalent for clients in aerospace, chemical, and oil industries. It delivers the same performance as Inconel 625 but at a lower cost—ideal for projects needing to balance quality and budget. Our team provides custom machining and heat treatment for GH3625 components, ensuring they meet Inconel 625’s strict standards. For businesses looking to cut costs without sacrificing durability, GH3625 is the smart choice.

FAQ

1. Is GH3625 a true Inconel 625 equivalent?

Yes! Its chemical composition, mechanical properties, and corrosion resistance match Inconel 625. It’s tested to perform the same in high-heat and acidic environments—with the added benefit of lower material costs.

2. Can GH3625 be used in marine heat exchangers?

Absolutely. Its high pitting resistance and seawater corrosion protection match Inconel 625. It’s ideal for marine heat exchangers, outperforming stainless steel and Monel 400 in long-term use.

3. What’s the lifespan of GH3625 parts compared to Inconel 625?

They’re nearly identical. In aerospace components (e.g., turbine blades), GH3625 lasts 7000–8000 flight hours—same as Inconel 625. In chemical reactors, both last 5–7 years with proper maintenance.