# Inconel for Cylinder Liners



## Woodster (Sep 23, 2014)

As the title suggests, has anyone tried Inconel for cylinder liners? I can get hold of a number of 6 inch long x 35mm Dia pieces all with a 20mm super finished bore, dead parallel and sized to + .005mm/ + .008mm on the nominal 20mm bore. I can get both 625 and 725 grades.
Initial research suggest that this stuff would be a great choice for liners.
Any body tried it?


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## abby (Sep 23, 2014)

Inconel would probably make very good cylinder liners but if you have to thin down the walls to something sensible it is not easy to machine and is very prone to work hardening.


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## Entropy455 (Sep 23, 2014)

When money is no object, engine manufacturers still chose a simple 100-70-03 ductile iron cylinder liner, and case-harden it. Whereas Inconel is an expensive metal, and has limited real-world applications. Unless you are seeking to obtain a corrosion resistant cylinder liner, I would avoid the stuff. There are much better, and cheaper materials to construct cylinder liners from. . . .


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## MachineTom (Sep 27, 2014)

If you plan on fueling your engine with Hydrazine, or uranium it would be a good choice. 

I'd suggest you buy some, and give the guys a report of how it machines, drill, turn and bore. I'd guess it would be a short report, Tough difficult impossible, depending on your equipment and skill.

You will quickly see my Steel, Cast Iron, brass and Aluminum, are the materials of choice with model engines.


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## Woodster (Sep 27, 2014)

I don't have to buy any. I can get it from work for free. With a Pre finished precision bore. I also machine the stuff, and worse, so know exactly how it machines. Like any Nickel based alloy, it's fine with the right tooling, speeds and feeds, and of course, a bloody great big CNC lathe! As far as drilling goes, I work for specialist deep drilling company as a CNC Turner/Programer. We do a few parts for an Electron Beam welding company and have to drill a 3.2mm hole through a 16.omm rod thats 700mm long, from one end! I then turn the stuff down to 12.7mm +0.05/-.00 over the entire length. With the right tools and know how.......

After doing a little research, it seems to be the perfect material for liners so i was simply wondering if it had been tried by any members.


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## Charles Lamont (Sep 27, 2014)

At an educated guess I would be very doubtful of its wearing properties.


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## Woodster (Sep 27, 2014)

Charles Lamont said:


> At an educated guess I would be very doubtful of its wearing properties.



http://www.iosrjen.org/Papers/vol2_issue9 (part-3)/D0292332.pdf


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## Charles Lamont (Sep 27, 2014)

Woodster said:


> http://www.iosrjen.org/Papers/vol2_issue9 (part-3)/D0292332.pdf



That is a theoretical study based on a range of parameters they have chosen to consider. They have not reported any experience of actually trying it. They assume hardness is equal to wear resistance, which, at best, is something of an oversimplification.


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## Woodster (Sep 27, 2014)

Charles Lamont said:


> That is a theoretical study based on a range of parameters they have chosen to consider. They have not reported any experience of actually trying it. They assume hardness is equal to wear resistance, which, at best, is something of an oversimplification.



That's why I was asking if anyone had tried it. People on here have access to, and try all kinds of metals in there work etc, like i do. Theres always the scrap bin!


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## Entropy455 (Sep 27, 2014)

Which alloy of Inconel do you have access to?

Inconel alloy 600 in the annealed condition falls within the B-Rockwell scale, which is too soft for cylinder sleeves in my opinion. With a proper heat-treatment, Inconel 600 tubing can achieve a max of 34-HRC, with 143-ksi tensile & 124-ksi yield strengths. This is adequate strength, however Inconel is well known for its ability to gall - even when hard. Also remember that Inconel is susceptible to stress-corrosion-cracking at elevated temperatures. So do you have access to the hard stuff, or the annealed stuff? If you are machining it, its likely annealed, or half-hard. . . .

A better choice would be 100/70/03 nodular iron. It has a 29-HRC hardness in the fully annealed state - with a 100-ksi tensile & 70-ksi yield strength. This nodular iron is strong and tough. It will achieve between 55-HRC and 60-HRC when heat-treated. It can be case-hardened, or through hardened. It is the choice alloy used to make heavy-duty diesel engine sleeves  sleeves that routinely exceed 1-million miles of service (or thousands and thousands of hours of service in marine applications). Even in the annealed state, 100/70/03 iron holds up very well as an engine cylinder liner. It's also widely used to make gears.

Inconel is a temperamental metal thats galls very easily. Its probably not the best choice for a cylinder sleeve. . . .


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