In demanding industrial environments such as oil and gas extraction, aerospace propulsion, marine systems, and power generation, the choice of alloy can determine whether a component lasts for decades or fails prematurely. Engineers and materials specialists must select materials capable of withstanding extreme temperatures, corrosive media, and mechanical stress.
Among the family of nickel-based superalloys, Alloy 625, Alloy 718, Alloy 725, and Alloy 716 are four of the most trusted materials. Each offers a unique balance of strength, corrosion resistance, weldability, and heat resistance. However, with growing requirements for improved machinability and cost-effectiveness, Alloy 716 has emerged as a next-generation alternative that bridges the gap between 718’s strength and 625’s corrosion resistance.
In this article, we will explore how Alloy 716 compares to Alloy 625, Alloy 718, and Alloy 725, covering composition, mechanical performance, corrosion resistance, applications, and overall value. As a professional supplier of nickel alloys, SASAALLOY provides expert guidance and certified materials to help clients choose the most suitable alloy for their critical operations.
1. Chemical Composition Comparison
The unique balance of elements in each alloy determines its properties. Below is a simplified comparison:
| Element | Alloy 625 (%) | Alloy 718 (%) | Alloy 725 (%) | Alloy 716 (%) |
|---|---|---|---|---|
| Nickel (Ni) | 58–63 | 50–55 | 55–59 | 50–55 |
| Chromium (Cr) | 20–23 | 17–21 | 19–22 | 17–21 |
| Molybdenum (Mo) | 8–10 | 2.5–3.3 | 7–8 | 2.5–3.0 |
| Niobium (Cb + Ta) | 3.15–4.15 | 4.75–5.5 | 3.15–4.15 | 4.5–5.5 |
| Titanium (Ti) | ≤0.4 | 0.65–1.15 | ≤0.35 | 0.6–1.0 |
| Aluminum (Al) | ≤0.4 | 0.2–0.8 | ≤0.35 | 0.2–0.8 |
| Iron (Fe) | ≤5.0 | Balance | ≤5.0 | Balance |
This composition table highlights Alloy 716’s close relation to Alloy 718 but with subtle adjustments for improved machinability, thermal stability, and weld performance.
2. Alloy 625 Overview
Alloy 625 (UNS N06625) is a solid-solution strengthened nickel-chromium-molybdenum alloy known for its outstanding corrosion resistance rather than extreme strength.
Key Features
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Excellent resistance to pitting, crevice corrosion, and chloride stress corrosion cracking.
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Superior performance in seawater, acids, and oxidizing/reducing media.
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Retains strength up to 600°C.
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Exceptional weldability and ductility.
Applications
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Offshore and marine environments
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Chemical processing and acid plant equipment
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Heat exchangers and evaporators
Limitations:
Alloy 625 offers lower tensile strength compared to precipitation-hardened alloys like 718 and 716. Therefore, it is preferred for corrosion-critical rather than load-bearing components.
3. Alloy 718 Overview
Alloy 718 (UNS N07718) is the industry standard for high-strength, precipitation-hardened nickel alloys.
Key Features
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High yield and tensile strength up to 700°C.
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Excellent fatigue, creep, and rupture resistance.
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Age-hardenable for tailored strength levels.
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Good oxidation and corrosion resistance.
Applications
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Aerospace engine components and turbine discs
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Downhole oil tools
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Fasteners and structural parts
Limitations:
Machining and welding Alloy 718 can be challenging due to work hardening and cracking tendencies, especially in complex geometries. This led to the development of Alloy 716.
4. Alloy 725 Overview
Alloy 725 (UNS N07725) is a derivative of Alloy 625 that has been precipitation-hardened to achieve much higher strength while retaining corrosion resistance.
Key Features
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Combines 625’s corrosion resistance with significantly higher mechanical strength.
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Resistant to hydrogen embrittlement and stress corrosion cracking.
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Certified for sour gas environments under NACE MR0175 / ISO 15156.
Applications
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Subsea valves, connectors, and tubular hangers
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Downhole completion tools
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Fasteners for marine and oilfield applications
Limitations:
Although Alloy 725 is strong and corrosion-resistant, it is more expensive than 625 and harder to machine due to its precipitation-hardened structure.
5. Alloy 716 Overview
Alloy 716 was developed to address the limitations of Alloy 718, offering improved machinability, weldability, and stability without sacrificing strength. It retains the same base chemistry but includes controlled titanium and aluminum content and optimized grain structure.
Key Features
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High strength comparable to Alloy 718.
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Enhanced machinability and formability — easier to process.
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Excellent resistance to chloride stress corrosion cracking.
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Outstanding thermal stability up to 700°C.
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Compliant with NACE MR0175 / ISO 15156 for sour gas environments.
Applications
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Aerospace engine components
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High-pressure valves and wellhead equipment
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Turbine shafts and fasteners
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Chemical plant reactors and marine systems
SASAALLOY supplies Alloy 716 in bars, plates, tubes, and forgings, all certified with EN 10204 3.1 / 3.2 inspection documentation.
6. Mechanical Property Comparison
| Property | Alloy 625 | Alloy 718 | Alloy 725 | Alloy 716 |
|---|---|---|---|---|
| Yield Strength (MPa) | 450–600 | 1000–1100 | 850–950 | 1000–1100 |
| Tensile Strength (MPa) | 800–950 | 1200–1400 | 1100–1250 | 1200–1350 |
| Hardness (HRC) | 20–25 | 35–45 | 32–42 | 35–45 |
| Max Service Temp (°C) | 600 | 700 | 650 | 700 |
| Density (g/cm³) | 8.44 | 8.19 | 8.36 | 8.19 |
From this data, Alloy 716 clearly matches Alloy 718 in strength while maintaining better manufacturing characteristics and heat resistance.
7. Corrosion Resistance Comparison
A. In Chloride Environments
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Alloy 625 and 725 offer the best corrosion resistance due to high molybdenum content (7–10%).
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Alloy 716 provides excellent performance similar to 718 but slightly less than 625.
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In seawater and brine systems, 716 still resists pitting and crevice corrosion effectively.
B. In Acidic Media
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Alloy 625 and 725 outperform 718 and 716 in strong acids like H₂SO₄ or HCl.
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However, Alloy 716 shows strong resistance in moderate acid concentrations and oxidizing conditions.
C. In Sour Gas (H₂S) Environments
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Alloy 725 and 716 are both NACE MR0175 certified, making them ideal for sour gas wells.
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Alloy 716’s nickel-chromium-molybdenum balance ensures high resistance to sulfide stress cracking and hydrogen embrittlement.
8. Fabrication and Weldability
| Aspect | Alloy 625 | Alloy 718 | Alloy 725 | Alloy 716 |
|---|---|---|---|---|
| Weldability | Excellent | Moderate (risk of cracking) | Good | Excellent |
| Machinability | Good | Difficult | Moderate | Very Good |
| Heat Treatment | Not age-hardened | Age-hardened | Age-hardened | Age-hardened |
| Formability | Excellent | Moderate | Moderate | Good |
Alloy 716 offers the best overall balance — it retains the weld strength and hardness of Alloy 718 but with easier fabrication and lower cracking risk. This makes it cost-effective for complex components.
9. Thermal and Oxidation Performance
Alloy 716 maintains structural and mechanical integrity at high temperatures up to 700°C (1300°F), similar to 718, but with less microstructural instability.
The alloy forms a protective oxide layer that shields against oxidation and scaling, ensuring reliable long-term service in turbines, exhaust systems, and chemical reactors.
10. Cost and Availability Comparison
| Alloy | Relative Cost | Availability | Typical Use Focus |
|---|---|---|---|
| 625 | Moderate | Widely available | Corrosion-critical systems |
| 718 | Moderate | High demand in aerospace | High-strength applications |
| 725 | High | Specialty oilfield alloy | Sour gas, high corrosion |
| 716 | Moderate | Growing industrial use | High strength + machinability |
Alloy 716 delivers a strong cost-performance advantage by combining the machinability of 625 with the strength of 718 — making it an excellent choice for large-scale industrial manufacturing.
11. Summary – Alloy 716 vs. 625, 718, 725
| Property | Alloy 625 | Alloy 718 | Alloy 725 | Alloy 716 |
|---|---|---|---|---|
| Strength | Medium | Very High | High | Very High |
| Corrosion Resistance | Excellent | Good | Excellent | Very Good |
| Weldability | Excellent | Moderate | Good | Excellent |
| Machinability | Good | Difficult | Moderate | Excellent |
| Sour Gas Resistance | Moderate | Limited | Excellent | Excellent |
| Temperature Limit | 600°C | 700°C | 650°C | 700°C |
| Cost Efficiency | Good | Good | Fair | Excellent |
Verdict:
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Choose Alloy 625 for maximum corrosion protection.
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Choose Alloy 718 for extreme mechanical strength.
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Choose Alloy 725 for sour gas and deep-sea resistance.
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Choose Alloy 716 when you need high strength, corrosion resistance, easy fabrication, and cost efficiency — all in one material.
12. Why Choose SASAALLOY for Nickel-Based Superalloys
SASAALLOY provides high-quality nickel-based alloys including Alloy 625, 718, 725, and 716 in multiple forms — bars, plates, tubes, and forgings — all tested and certified for performance under the most demanding conditions.
Our Advantages:
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Compliance with ASTM B637, AMS 5662/5663, NACE MR0175 / ISO 15156.
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Full traceability with EN 10204 3.1 / 3.2 certification.
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Custom heat treatment, forging, and machining services.
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Global supply network and fast logistics support.
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Technical expertise to assist with alloy selection and design optimization.
When industries require durability under high stress and corrosive conditions, SASAALLOY delivers reliability, precision, and quality.
Conclusion
Alloy 716 stands out as a next-generation nickel-based superalloy, engineered to bridge the gap between 718’s strength and 625’s corrosion resistance. It provides an excellent balance of mechanical performance, weldability, and cost-efficiency, while also meeting strict standards for sour gas and high-temperature environments.
Compared to Alloy 625, 718, and 725, Alloy 716 offers superior processability and stable performance, making it ideal for modern aerospace, oilfield, and energy applications.
For industries demanding high-performance materials that can handle pressure, heat, and corrosion simultaneously, SASAALLOY is your trusted partner — providing certified Alloy 716 and related superalloys built for endurance and excellence.
Post time: Oct-23-2025