Room for advancement in metallurgy?

[201Steve]

With all the talk we have of corrosion, heat, and failure of metals under different circumstances, it almost seems that we have tapped the full scope of metallurgy already, since there are often so few good alternatives it seems. Here's an Article from a trucking publication I found interesting.

 

Engine manufacturer Cummins has developed a high-temperature steel alloy in collaboration with Oak Ridge National Laboratory (ORNL) that the companies stated in a press release will increase engine durability and efficiency.

Cummins has worked with ORNL since 2018 to research and develop an alternative steel alloy with improved high-temperature oxidation resistance and strength while maintaining affordability.

“The partnership with Oak Ridge National Laboratory and development of the new material shows the serious potential for improvements and efficiencies for our engines,” said Corey Trobaugh, Cummins’ director of applied science and technology.

See also: Cummins reaches engine milestone: 2.5M engines made at Jamestown plant

Previous materials have limited engine efficiency gains and emissions reductions and prohibited engineers from extracting more heat from the combustion process, due to materials degrading prematurely from oxidation, scaling, and cracking, according to the release.

The new material is stronger at elevated temperatures compared to the most commonly used commercial steel, 4140, and has virtually eliminated those degradation pathways, according to Cummins. When comparing the new alloy to 4140 steel, the new alloy exhibited 85% greater ultimate tensile strength (the maximum stress a material can withstand without breaking while being stretched or pulled before) and 143% greater fatigue strength (the maximum cyclical stress that can be applied for the material to withstand at least 10 million cycles before failure) at 600 degrees Celsius (1,112 F).

 

In an engine test of pistons manufactured from the new material, no cracking occurred, and very little oxidation or scaling occurred, according to Cummins. The new medium carbon steel offers at least a 50 C (122 F) increase in temperature capability as compared to current 4140 steels. Development of the new alloy was supported by the Lightweight Materials Consortium (Lightmat) program out of the Department of Energy’s Vehicle Technologies Office.

[Fly Boomer]

One of these days, if we keep playing with BeV accelerators, we will either create a black hole that swallows the known universe, or create some new materials that far exceed what we can create by melting stuff in a big vat.

[KSMooniac]

Sounds like a great advancement in a relatively niche application... perhaps some day it might trickle down to an aircraft diesel engine and make it more competitive weight-wise with gasoline engines.  

There have been advances in aircraft structural alloys over the years, but unfortunately, they come at very high cost and don't buy their way on to an airplane very easily.

[N201MKTurbo]

They are talking about steel pistons. Pistons failing hasn't been a big issue with our engines. Our engines would get a lot heavier if we made the pistons and cylinder heads out of steel.

[KSMooniac]

23 minutes ago, N201MKTurbo said:

They are talking about steel pistons. Pistons failing hasn't been a big issue with our engines. Our engines would get a lot heavier if we made the pistons and cylinder heads out of steel.

Agreed, but I was specifically thinking of reducing weight in a next-gen aircraft diesel engine.  I don't think diesels are too competitive today due to cost and weight, at least in terms of a retrofit application for the existing fleet.  If they could get lighter with advanced materials, then that changes things tremendously.  

[201Steve]

I think the take away is, where we often assume science has the metallurgy thing pretty well mapped out to its limit, Maybe not, as advancements are still happening. Or so it seems. 

[A64Pilot]

Metals are advancing rapidly, for instance due to continuous refining Titanium has come way down in price and there isn’t really much of a reason it hasn’t replaced SS, but will I think. I had Allied Titanium make my sailboat chainplates from grade 5 Ti and was told that on batches of 5,000 or greater that they could often beat Stainless hardware fastener prices.

‘It’s still a bear to machine and weld though so don’t expect titanium exhausts for awhile.

Diesels have issues beyond weight, weight is an issue because compared to gas they have to be overbuilt, if a lightweight metal were to appear, gas could lose weight just as much.

Biggest issue I see is for some reason the aircraft Diesels haven’t gone to Common rail, Common Rail is a huge performance increase and much lower NVH, noise vibration and harshness, Common Rail may likely solve the prop issue for example and allow a lighter engine due to its decreased NVH.

Personally I think if we were going to get aircraft Diesels we would have 20 years ago, even little Maule Certified a Diesel back then, then the engine manufacturer dried up. I flew it, it had some issues, like a go-around for instance, sort of like an old turbine, advance throttle and wait for boost to build.

https://www.aviationconsumer.com/aircraftreviews/engines/maules-m-9-aero-diesel/

The biggest reason our cars aren’t aluminum now is the advancement of lightweight high strength steels, newer cars are lighter, stronger and safer from using this steel and save so much weight that aluminum isn’t as attractive as it once was.

 

Edited June 19, 2023 by A64Pilot

[Hank]

5 hours ago, A64Pilot said:

The biggest reason our cars aren’t aluminum now is the advancement of lightweight high strength steels, newer cars are lighter, stronger and safer from using this steel and save so much weight that aluminum isn’t as attractive as it once was.

Based on my experience owning an aluminum Mooney, I will not have an aluminum vehicle. When I scratch my car, out comes the touchup paint and I'm done. No sanding, etching, priming, turning a narrow scratch into a foot-wide area for the final topcoat. And steel will bend, then can often be popped right back into place, but not aluminum--it's so soft that hitting it enough to make a dent will also stretch it, so it cannot "pop back into place." No thank you, keep your aluminum vehicle. Just one more reason to avoid the F-150 . . . . . Also, I can wash my [steel] car with pretty much whatever I want, but am ultra-careful with the cleaners used on my [aluminum] Mooney.

[Fly Boomer]

13 hours ago, A64Pilot said:

Personally I think if we were going to get aircraft Diesels we would have 20 years ago,

DeltaHawk, for various reasons, has been developing their recently-certified engine for longer than that.  Apparently, it's harder than it looks.