Inconel 718 per AMS 5962

Q: What is the difference between “standard” Inconel 718 and Inconel 718 per AMS 5962

A: While nothing about Inconel 718 is standard, however the most popular variety of Inconel 718 bolts is per ASTM B637. For this version of s, the bolts are age hardened to have a minimum tensile strength of 185 KSI and minimum yield of 150 KSI. Inconel fasteners per AMS 5962 are not only age hardened but they are also cold worked or work strengthened to produce an extremely high minimum tensile strength of 220 KSI.

Making the Right Choice: Inconel 600, 601, 625 & 718

Inconel bolts are a nickel alloy fastener that are known for their use in high temperature applications that also require high strength. Many grades are also used for their excellent level of corrosion resistance in harsh chemical environments. This brief newsletter highlights the unique attributes of each Inconel bolt grade.

Inconel 600 Bolts
High Temperature Resistance
• Ideal for oxidation and carburization resistance at high temperatures
• Good resistance to chlorine media such as dry chlorine, chloride-ion stress corrosion cracking and hydrogen chloride gases at moderate temperatures.
• Excellent for furnace components and chemical processing equipment.

Inconel 601
Excellent Mechanical Properties
• Similar oxidation and carburization resistance to grade 600 with improved high strength and mechanical toughness.
• 107 ksi tensile strength compared to 93ksi of grade 600.
• Good creep and rupture strength, as well as metallurgical stability in heat.
• Ability to stave off strain at high temperatures.

Inconel 625
Corrosion Resistance
• Best known for its high temperature corrosion resistance.
• Often used in chemical processing, nuclear power plants and oil & gas.
• Good resistance to harsh chemicals: sulfuric, hydrofluoric and phosphoric acids.
• Corrosion resistance is often comparable to that of Hastelloy C276.

Inconel 718
Superior Strength & Corrosion Resistance
• FAR exceeds all Inconel alloys and most materials available to industry in terms of high strength with the exception of a few alloys like MP35N.
• Extreme high strength with a min of 185ksi UTS and 150ksi yield strength per ASTM B637. A work hardened version that has min of 220 ksi UTS.
• Ideal for high strength, corrosive applications such as gas turbine engines, down-hole oil & gas and aerospace.

High Strength Fasteners for Hydrochloric Acid (HCl)

Q: I’m in need of a high strength fastener that can withstand moderate concentrations of hydrochloric acid (HCl) 25%? Can I use Hastelloy Bolts? I need a bolt that can handle a yield of about 100ksi and temperatures around 100F.

A: Hastelloy bolts are definitely ideal in this concentration of hydrochloric acid. Hastelloy C276 bolting is usable in these temperatures and concentrations, but can’t handle the yield strength you need. Hastelloy C276 has a yield around 49 ksi – about half your requirement. For your situation, you have two choices. Incoloy 925 bolts have similar corrosion resistance to alloy 825 which can take the HCl, yet they are age hardened to offer a lot higher strength than 825. Alloy 925 bolts have a yield around, 120ksi. In addition, you can also try Inconel 718 bolts which are an age hardened form of 625. Therefore it offers similar corrosion resistance but has a yield of 175ksi. Both will still show slight corrosion over time but will be the best options considering you high strength requirements.

Difference between Waspaloy and Inconel 718 fasteners

I have a high temperature and strength application when would I choose Waspaloy bolts verses Inconel 718 bolts?

Great question. Waspaloy and Inconel 718 bolts are both excellent in high temperature strength situations. In terms of strength, Inconel 718 has a edge over Waspaloy offering 210 ksi (ultimate tensile strength) and 175 ksi yield compared to an Inconel 718 bolt which can handle 193 ksi (UTS) and 132 ksi yield. Although Inconel bolts are slightly stronger, Waspaloy is more temperature resistant . Inconel 718’s maximum temperature usage is 1300F, where Waspaloy can be used to 1600F.