High Tensile Inconel 718 Bolts | Corrosion & Heat Resistant Industrial Fasteners

Inconel 718 bolts, also known as 718 Inconel or high-tensile Inconel 718 stainless steel fasteners, are age-hardened nickel-chromium-based superalloy bolts engineered for the harshest industrial environments. Designed to resist oxidation and corrosion under high pressure and elevated temperatures, they offer a yield strength of up to 1,270 MPa and remain usable at temperatures as high as 1800°F (982°C). Consequently, these fasteners are extensively used in aerospace, automotive, marine, chemical, oil & gas, and power generation industries.

Conventional steel fasteners often fail under repeated thermal cycling or corrosive conditions, resulting in premature fatigue, loosening, or unexpected equipment downtime. In contrast, Inconel 718 fasteners maintain strength, ductility, and structural integrity across both high and cryogenic temperatures, effectively addressing these common industrial pain points.

Understanding Material Properties and Heat Resistance

These superalloy fasteners are precipitation-hardened (age-hardened) nickel-chromium alloys derived from Inconel 625. Age hardening involves heating and quenching the alloy to stabilize the grain structure, significantly enhancing tensile strength and creep resistance. Additional cold working further boosts mechanical properties.

Key mechanical characteristics:

• Yield Strength: up to 1,270 MPa

• Tensile Strength: 1,240–1,380 MPa (up to 220 ksi with cold working)

• Hardness: 280–340 HB

• Density: 8.19 g/cm³

For instance, aerospace turbine assemblies using these fasteners maintain tensile strength after 1,000 thermal cycles at 650°C, outperforming conventional steel bolts.

Corrosion Resistance and Chemical Compatibility of Inconel 718 Bolts

Thanks to its nickel-chromium matrix, Inconel 718 offers exceptional resistance against corrosion:

• Resistant to chloride and sulfide stress-corrosion cracking

• Effective in H₂S, CO₂, chloride, and sour gas environments

• Performs reliably in aqueous corrosion and high-temperature oil & gas drilling conditions

Molybdenum prevents pitting, while chromium enhances resistance to sulfur compounds and mild oxidizers. As a result, Inconel 718 fasteners maintain structural integrity in aggressive chemical and marine environments, reducing unexpected failures and maintenance costs common with standard steel bolts.

Threading, Welding, and Machining Recommendations for Inconel 718 Bolts

Threading:

• Threads can be rolled or cut in the annealed condition

• Post age-hardening, machining is more challenging but possible for high-strength applications

Welding:

• Excellent weldability in annealed and aged conditions

• Minimizes cracking risk due to age hardening

• Welding in aged condition produces a softened heat-affected zone

Best Practice: Preheat and controlled cooling are recommended to avoid residual stress when welding age-hardened bolts. Use carbide or high-speed steel tooling for machining to maintain thread quality.

AMS and ASTM Specifications for Certified Inconel 718 Bolts

Inconel 718 fasteners comply with multiple standards: AMS 5596, AMS 5662, AMS 5663, AMS 5962, ASME Case 2222-1, ASME SFA 5.14, ASTM B637, ASTM B670, EN 2.4668, GE B50TF14, GE B50TF15, UNS N07718.

Common grades and features:

• AMS 5662: Solution-annealed, softest, moderate strength

• AMS 5663: Age-hardened, higher tensile strength and hardness

• AMS 5962: Cold-worked post solution annealing, min tensile strength 220 ksi, suitable for critical high-strength applications up to 900°F

• AMS 5596: Solution-treated sheet and plate; creep resistance to 1300°F, oxidation resistance up to 1800°F

• ASTM B637: Hot- and cold-worked precipitation-hardened; ensures mechanical performance for high-temperature service

These specifications guarantee consistent strength, hardness, and fatigue resistance, addressing failure risks in extreme environments.

Inconel 718 Bolts Industry Applications for High-Temperature and Corrosive Environments

Aerospace Applications

Applications: Turbine engines, liquid oxygen turbo-pumps, airframe components
Maintain over 1,200 MPa tensile strength after 1,000 thermal cycles at 650°C. Standard steel bolts often crack or loosen, but Inconel 718 prevents high-temperature fatigue failures.
Pain point solved: High-temperature cracking in aerospace assemblies.

Case Study: A leading aerospace OEM retrofitted Inconel 718 bolts in liquid oxygen turbo-pumps, reducing bolt replacement frequency by 60% during high-temperature operation.

Automotive Engines

Applications: High-performance engine components, exhaust manifolds
Withstand up to 500,000 engine cycles without fatigue failure. Resistant to thermal cycling, vibration, and corrosive exhaust gases, reducing maintenance and improving engine reliability.

Case Study: Performance automotive manufacturer replaced standard steel fasteners with Inconel 718 bolts in exhaust manifolds, resulting in a 70% decrease in engine maintenance intervals.

 Marine Equipment

Resist pitting and chloride-induced cracking in saltwater and high-humidity environments, ensuring uninterrupted offshore operation.
Pain point solved: Prevents corrosion-related downtime.

Case Study: Offshore wind farm operators using Inconel 718 bolts reported zero fastener-related corrosion failures over 3 years of continuous operation.

Chemical Plants and Oil & Gas Industry

Withstand H₂S, CO₂, and sour gas exposure for thousands of hours, minimizing operational risk and maintenance compared to conventional bolts.

Case Study: An oil & gas facility retrofitted 718 bolts in sour gas pipelines, reducing emergency bolt replacement by 80% in the first year.

Power Generation and Turbine Assemblies

Steam generators, nuclear reactors, and turbines use Inconel 718 bolts to resist creep and fatigue at 600–700°C over repeated cycles, ensuring reliable power generation with minimal downtime.

Case Study: Nuclear power plant upgraded to Inconel 718 fasteners in turbine assemblies, extending maintenance intervals and preventing thermal fatigue failures.

Conventional Steel Bolts vs Inconel 718 Bolts

Case Study: How Inconel 718 Bolts Solved a Critical Aerospace Reliability Challenge

A leading aerospace manufacturer faced recurring bolt failures in liquid oxygen turbo-pumps used in next-generation launch vehicles. Conventional high-strength steel fasteners developed micro-cracks after repeated thermal cycles, leading to loosening, leakage, and unplanned downtime. Each failure required urgent replacement and delayed flight schedules, costing millions in rework and penalties.

After consulting with Welleshaft’s engineering team, the company decided to switch to AMS 5663-certified Inconel 718 bolts. These bolts maintained over 1,200 MPa tensile strength after 1,000 thermal cycles at 650°C, eliminating fatigue-related cracking.

Results within 12 months:

• Bolt replacement frequency reduced by 60%

• Overall maintenance downtime decreased by 35%

• Improved customer trust due to higher reliability of aerospace assemblies

The switch not only solved the technical issue but also saved millions in operational costs while ensuring compliance with aerospace safety standards.

Why Choose Welleshaft for Inconel 718 Bolts

Welleshaft offers certified Inconel 718 fasteners with:

• Compliance with AMS and ASTM standards

• Expertise in high-temperature, marine, oil & gas, and aerospace applications

• Technical support for material selection, threading, welding, and machining

• Reliable supply chain for industrial projects worldwide

Buy certified Inconel 718 bolts for aerospace, automotive, marine, chemical, and power generation applications. Request a quote for custom high-performance fasteners today.

Frequently Asked Questions

Q1: Why choose Inconel 718 bolts over stainless steel?
A: Inconel 718 provides superior strength, corrosion resistance, and high-temperature stability, preventing fatigue and failure in extreme industrial environments.

Q2: Can Inconel 718 bolts be used for welding applications?
A: Yes, they have excellent weldability in both annealed and age-hardened conditions with proper preheating and cooling procedures.

Q3: Are custom sizes and threads available?
A: Yes, Inconel 718 bolts are available in a wide range of AMS/ASTM grades and custom dimensions for industrial requirements.