In industries such as aerospace, oil & gas, energy, and marine engineering, nickel-based superalloys are chosen for their outstanding strength, heat resistance, and corrosion protection. Among them, Alloy 718 has long been the benchmark material for high-temperature applications. However, with growing demands for improved machinability and cost efficiency, a new generation alloy—Alloy 716—has emerged as a superior alternative.
Both alloys share similar compositions and mechanical properties, yet Alloy 716 is specifically optimized for better machinability and weldability without compromising strength or performance. This article explores how Alloy 716 compares with Alloy 718 in terms of machinability, processing behavior, and industrial performance.
As a leading supplier of high-performance nickel alloys, SASAALLOY provides certified materials like Alloy 716 and 718 for demanding industrial applications worldwide.
1. Understanding Alloy 718 – The Industry Standard
Alloy 718 (UNS N07718) is a precipitation-hardened nickel-chromium alloy developed to deliver high tensile strength, creep resistance, and corrosion protection up to 700°C (1300°F).
Key Features:
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Excellent strength from cryogenic to high temperatures
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Outstanding resistance to oxidation and corrosion
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High fatigue and rupture strength
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Proven performance in aerospace, energy, and oilfield applications
However, while Alloy 718’s mechanical performance is unmatched, its machinability is notoriously poor. The material tends to work-harden rapidly, causing tool wear, surface damage, and high machining costs. This limitation led to the development of Alloy 716, a modified version with improved machinability.
2. What Is Alloy 716?
Alloy 716 is a nickel-chromium-iron-molybdenum superalloy closely related to 718 but optimized for processing performance. Its chemical composition is slightly adjusted to improve cutting behavior and reduce work hardening tendencies.
Typical Chemical Composition (%):
| Element | Alloy 718 | Alloy 716 |
|---|---|---|
| Nickel (Ni) | 50–55 | 50–55 |
| Chromium (Cr) | 17–21 | 17–21 |
| Iron (Fe) | Balance | Balance |
| Molybdenum (Mo) | 2.5–3.3 | 2.5–3.0 |
| Niobium (Cb + Ta) | 4.75–5.5 | 4.5–5.5 |
| Titanium (Ti) | 0.65–1.15 | 0.6–1.0 |
| Aluminum (Al) | 0.2–0.8 | 0.2–0.8 |
| Carbon (C) | ≤0.08 | ≤0.08 |
These small but significant compositional differences give Alloy 716 better thermal and microstructural stability during machining, resulting in smoother surface finishes and longer tool life.
3. Why Machinability Matters
In modern manufacturing, machinability determines production efficiency, tool life, and overall cost. For nickel alloys like 718, poor machinability leads to:
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Rapid tool wear due to high hardness and heat generation
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Work hardening that increases cutting resistance
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Built-up edge formation on cutting tools
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Surface tearing or microcracking
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Frequent tool changes and downtime
Alloy 716 was engineered to overcome these issues by enhancing chip formation, lowering cutting forces, and minimizing thermal damage.
4. Alloy 716 vs Alloy 718: Machinability Comparison
| Property | Alloy 718 | Alloy 716 |
|---|---|---|
| Machinability Rating (relative) | 35–40% | 55–60% |
| Work Hardening Tendency | High | Moderate |
| Cutting Temperature | Very High | Lower (better heat control) |
| Tool Wear Rate | Rapid | Reduced (up to 30% longer tool life) |
| Surface Finish Quality | Fair | Excellent |
| Chip Formation | Continuous, tough | Shorter, easier to evacuate |
| Feed & Speed Compatibility | Narrow range | Wider range (more flexible) |
Alloy 716 provides 20–30% better machinability than 718 under similar cutting conditions, significantly improving production throughput and cost-effectiveness.
5. Metallurgical Reasons for Better Machinability in Alloy 716
A. Controlled Microstructure
Alloy 716’s fine and uniform grain structure improves chip breakage and reduces tool pressure.
B. Reduced Work Hardening
The alloy’s balanced titanium and niobium levels lower strain-induced hardening during cutting.
C. Stable Thermal Conductivity
Better heat dissipation minimizes localized temperature rise, preventing tool edge softening and wear.
D. Optimized Phase Stability
A more stable γ (gamma) matrix minimizes carbide precipitation along grain boundaries during machining.
These factors collectively lead to smoother cutting action, reduced tool wear, and improved productivity.
6. Cutting Tool Selection and Parameters
Recommended Tools for Alloy 716:
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Carbide tools (coated or uncoated) for roughing operations
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Ceramic or CBN (Cubic Boron Nitride) inserts for finishing at high speeds
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High-pressure coolant systems to control cutting temperature
Typical Cutting Conditions:
| Operation | Cutting Speed (m/min) | Feed (mm/rev) | Depth of Cut (mm) |
|---|---|---|---|
| Turning | 25–45 | 0.1–0.3 | 1.5–3.0 |
| Drilling | 10–20 | 0.05–0.2 | — |
| Milling | 15–35 | 0.05–0.2 | 1.0–2.0 |
Compared with 718, Alloy 716 allows higher cutting speeds and feeds, translating to shorter cycle times and lower production costs.
7. Tool Wear and Surface Finish
Alloy 718 tends to cause notch wear and flank wear due to its hardness and poor chip evacuation. In contrast, Alloy 716’s improved machinability yields:
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Cleaner chip formation
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Reduced tool edge build-up
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Extended insert life
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Smoother machined surfaces (Ra < 1.6 µm achievable)
This not only improves productivity but also reduces the need for post-machining polishing or grinding operations.
8. Heat Treatment Effects on Machinability
Both 718 and 716 are typically machined in the solution-annealed condition before aging. However, Alloy 716 responds better to machining even after partial precipitation due to its stable microstructure.
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Annealed 716: Best machinability; easy chip control.
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Aged 716: Slightly harder but still more machinable than aged 718.
Post-machining heat treatment restores full mechanical strength without affecting dimensional accuracy.
9. Economic and Operational Advantages
Switching from Alloy 718 to 716 provides measurable benefits in manufacturing:
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30–40% reduction in machining time per part
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Up to 25% lower tooling costs due to slower wear rates
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Less downtime for tool changes or setup adjustments
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Improved surface integrity and lower scrap rates
These advantages make Alloy 716 particularly attractive for high-volume production of aerospace, oilfield, and turbine components where precision and cost efficiency are essential.
10. Industrial Applications of Alloy 716
Because of its superior machinability and mechanical properties, Alloy 716 is widely used in:
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Aerospace: Turbine discs, fasteners, engine casings
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Oil & Gas: Downhole tools, wellhead valves, connectors
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Power Generation: Turbine blades, compressor parts
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Marine & Offshore: Pump shafts, corrosion-resistant fittings
Alloy 716’s enhanced fabrication performance allows manufacturers to produce complex geometries and tight tolerances with less rework and waste.
11. Comparison Summary – Alloy 716 vs Alloy 718
| Criteria | Alloy 718 | Alloy 716 |
|---|---|---|
| Strength | Excellent | Excellent (equal to 718) |
| Corrosion Resistance | Very Good | Very Good |
| Machinability | Difficult | Improved (~30% better) |
| Weldability | Moderate (risk of cracking) | Excellent |
| Heat Resistance | Up to 700°C | Up to 700°C |
| Fatigue Resistance | Excellent | Excellent |
| Cost Efficiency | High machining cost | Lower total cost |
| Availability | Widely available | Growing availability |
Conclusion: Alloy 716 retains all the strengths of 718—mechanical integrity, corrosion resistance, and high-temperature stability—while significantly improving machinability and manufacturing efficiency.
12. SASAALLOY – Your Reliable Source for Nickel-Based Superalloys
SASAALLOY is a professional manufacturer and global supplier of nickel-based superalloys, stainless steels, and corrosion-resistant materials, offering complete solutions for aerospace, marine, and energy industries.
Our Advantages:
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Full range of Alloy 716, 718, 625, and 725 in bars, plates, tubes, and forgings
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Certified to ASTM B637, AMS 5662/5663, and NACE MR0175 / ISO 15156
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Documentation provided under EN 10204 3.1 / 3.2 certification
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Custom heat treatment and machining services
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Technical expertise for alloy selection and processing optimization
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Global logistics network ensuring prompt delivery
With decades of metallurgical experience, SASAALLOY delivers consistent quality and performance to clients in aerospace, energy, and oilfield manufacturing sectors.
Conclusion
Alloy 716 represents a significant improvement in machinability compared with Alloy 718, offering the same mechanical strength and corrosion resistance but with easier cutting, longer tool life, and lower manufacturing cost.
Its balanced composition and stable microstructure make it ideal for modern machining centers that demand precision and efficiency. As industries continue to seek cost-effective solutions for high-performance materials, Alloy 716 is rapidly becoming the preferred choice for complex components previously made from 718.
When quality, reliability, and performance matter, SASAALLOY provides the materials and expertise needed to help your project succeed — with Alloy 716 leading the way in next-generation machinable nickel alloys.
Post time: Oct-23-2025