Tag: Inconel 718 bolts for high strength

17-4 Corrosion Resistance to Sulfuric Acid & Inconel

Q: Are there any materials I can use with the strength of 17-4PH in the H1150 heat treat, but with better corrosion resistant properties. I have low levels of sulfuric acid and chlorides that seem to be attacking the 17-4 steel.
A: The best choice for both extreme strength and corrosion would be Inconel 718 bolts. Inconel 718 may be overkill as it can provide excellent corrosion resistance to concentrated acids and chlorides at high temperatures while boasting min yield of 175KSI. However if you are looking for a big improvement in both corrosion and strength this will do it. Another material worth considering would be Inconel 625.  This is basically the un-aged sister material of Inconel 718 having good corrosion resistance and a strength similar to that of 17-4 H1150.   Inconel 625 would a significant improvement in corrosion resistance to sulfuric acid over 17-4 PH while maintaining a similar strength.

Overview of Extreme High Strength Fasteners

Extreme high strength fasteners made from advanced alloys allow industries such as aerospace, mining, and oil & gas to push the limits of what is possible.  With requirements of ultimate tensile strengths beyond 200ksi this newsletter reviews these materials, their specific traits and niches.

 

17-4 PH
Age hardened, 17-4PH fasteners can range from 125 -200ksi, but in the H900 condition they are capable of yield strengths over 4x’s that of 316 stainless steel.
NICHE: Customized strength via several different age hardened conditions.

 

WASPALOY
Just under 200 ksi in UTI, Waspaloy fasteners maintains one of the highest strengths at elevated temperatures.
NICHE: Strength at extreme temperatures well over 1300F exceeding that of Inconel 718.

 

INCONEL 718
Inconel 718 bolts offers very high strength at high temperatures as well as excellent resistance to wide range of corrosive media.
NICHE: Unique combination of strength, temperature and corrosion resistance.

 

MP159
One of the strongest alloys, MP159 fasteners offer slightly less strength capabilities to sister alloy MP35N but can be used at greater temperatures to 1100F.
NICHE: Superior strength with good temperature resistance.

 

MP35N
MP35N bolts offer ultimate tensile strength up to 294ksi and are usable to 800F. Like MP159 they offer good corrosion resistance to most mineral acids, hydrogen sulfide, and seawater.
NICHE: Strongest fastener material commercially available.

 

When Strength AND High Temperature are Needed
Often high strength materials are needed in extreme temperature situations. This chart ranks the high temperature capabilities of these alloys.