45 replies to this topic

[F1Champion]

Hi, I've been recently reading articles suggesting that the 2003 Ferrari engine block will be made from cast Titanium.

I would just like to know what the advantages would be, because apart from strength wouldn't aluminium be the better metal because its lighter and dissipates heat better?

Thanks for any input.

[wati]

Smokin' idea! Aluminium is lighter? I'm not sure about it, but I might be wrong. I think Ti is lighter.

Wattie

[VAR1016]

Titanium is seldom used in its pure form; it is slilghtly denser (i.e. heavier) than aluminium alloys, but is generally stronger. I recall that Ferrari was using a titanium gearbox a few years ago;l I wonder what became of that?

My understanding is that the new explosion-casting of steel i s yielding some extremely strong and light castings.

VAR1016:smoking:

[Ferrari_F1_fan_2001]

Titanium is 5 times more expensicve than steel and i think its 3 times stronger, this caused some advantages and disadvantages,
a advantage being that its lighter and thus saves a crucial amouth of weight within the whole package

a disadvantage is that its harder to machine , and can cause components to fail, (as seen with Minardi at the 2001 italian GP) im sure there are other disadvantages but i cant think of any,

[Top Fuel F1]

Originally posted by F1Champion
Hi, I've been recently reading articles suggesting that the 2003 Ferrari engine block will be made from cast Titanium.

As I recall Ti is a real chore to cast and requires some unique techniques to be able to achieve a complex casting. I'd have to go back and research that to say much more about that.

Rgds;

[Top Fuel F1]

Re:

http://www.asm-intl....df/JMEP1975.pdf

I just came upon this and have to look it over. In the mean time look it over. Right at the beginning it looks like may be for prototyping.

[random]

I suppose the advantage of a titanium engine is that as a stressed member of the car, it can be of a smaller mass than it's aluminum equivilent while having the same or greater structural integrity. Although I doubt it will be much lighter, aluminum is lighter than titanium.

This grandprix.com article discusses the new methods of casting titanium and the likelihood of a Ferrari motor using the metal.

http://www.grandprix...ns/ns06832.html

[MRC]

While I'm too lazy to go actually look it up, I think the specific stiffness (stiffness/density) is comparable between for Ti and Al. Although it depends on what alloy you are talking about.

As far as I know, the strongest steels have a higher UTS than the strongest titanium alloys. Titanium is surely not 3 times stronger. One would have to compare specifc alloys. With something like an engine casing, toughness would have to come into play also.

[MRC]

Here is a link to a search for materials on the matweb site:

http://www.matweb.co...earchSubcat.asp

I don't know what aluminum alloy is currently used, nor what Ti alloy they would use, but it appears that Ti would have a higher spefic strength (yield or UTS).

[desmo]

Ti alloy block castings look pretty attractive given the mass reductions realized by substituting cast Ti alloy for other materials in critical transmission case and wheel upright applications. While Ti alloys typically exhibit outstanding specific UTS and yield stregth properties, their specific modulus of elasticity is similar to other competing materials. Ti is more dense than Al, so wall thicknesses will have reduced to realize a mass reduction. Merely substituting Ti for Al alloy without dimensional changes to suit would be pointless.

One F1 engine guy I communicated with seconds VAR's suggestion that explosion formed steel crankcases may offer the best potential for mass reduction. Weren't the Barnard designed Ferrari's cases of steel, nevermind the '50s Mercedes GP racers?

[random]

I've seen passing references to explosion forming, but can't seem to find any specific articles describing the process. Does anyone have more information?

[desmo]

Google Search for "Explosion Forming"

The explosion forming process can be done using capacitive electrical discharge or by conventional high explosives! Looks like fun. A crankcase, it appears to me in order to be made this way, will have to be done in pieces and then welded together. Steel lacks "wow factor" as an engineering material, but don't be fooled into thinking it can't be fully competitive with "sexier" materials for many applications.

[random]

Originally posted by desmo
A crankcase, it appears to me in order to be made this way, will have to be done in pieces and then welded together.

I was thinking the same thing, the crankcase seems too complex for this process. Unless perhaps they have a very complex multi-explosion approach.

(I must have misspelled my google search before, I didn't turn up those links)

[MRC]

Why not investment cast with some finish machining. I would think that you could acheive thin enough wall thicknesses with investment casting. Even with higher stiffness, as you go to a lower wall thickness, and have the same equivalent axial stiffness, I believe vibrations will go up, due to lower stiffness transversely (across a panel that is). Thus you have to compensate with more ribbing, to increase total stiffness. With lower wall thicknesses allowed you can get more from small, thin, stiffening ribs. Well, that't my understanding of it anyway (although not too good).

[MRC]

From a little searching on google it seems the minimum wall thickness for investment cast Ti, is somewhere around 1mm. I would have thought it to be a little less. Ah well.

[VAR1016]

Originally posted by desmo
[.

One F1 engine guy I communicated with seconds VAR's suggestion that explosion formed steel crankcases may offer the best potential for mass reduction. Weren't the Barnard designed Ferrari's cases of steel, nevermind the '50s Mercedes GP racers? [/B]

Well there seems to be no doubt that if it is toughness, strength (in torsion, compression and tension) then steel is really a very satisfactory material. I know that Boron and carbon composites are better is some respects, but I believe that F1 regulations declare that the engine must be of metallic material.

Now casting is always inferior to forging even though the foundrymen have refined their art spectacularly. I suspect that this explosion-casting (given sufficient explosive force) may provide a result that could be closer to forging than any casting done so far - and pressure die-casting is pretty impressive. I also suspect that the explosive forming could result in extremely light components - relative to their strength.

VAR1016

[Pioneer]

5.5.1 The basic structure of the crankshaft and camshafts must be made from steel or cast iron.
5.5.2 Pistons, cylinder heads and cylinder blocks may not be composite structures which use carbon or aramid fibre reinforcing materials.

Make of that what you will.
You could make the block out of non-metallic substances if you wanted to. I think.

[MRC]

Thanks for the rules Pioneer. From 5.5.2 it looks like you could use boron fibers as reinforcement depending on how you read that rule.

[VAR1016]

Originally posted by Pioneer
5.5.1 The basic structure of the crankshaft and camshafts must be made from steel or cast iron.
5.5.2 Pistons, cylinder heads and cylinder blocks may not be composite structures which use carbon or aramid fibre reinforcing materials.

Make of that what you will.
You could make the block out of non-metallic substances if you wanted to. I think.

Yes, that's true I suppose, but I note that they have banned carbon and aramids (e.g. Kevlar) which really rather rains on the parade.

VAR1016

[desmo]

MMCs which seldom or never use CF or aramid reinforcements are unambiguously legal for all engine parts. In fact the way I read the rules, even MMCs exceeding the specific modulus limit are unambiguously legal provided that the matrix metal is within the limit. I don't think the ban on CF and aramids has had much impact at all. These reinforcements are almost exclusively used with polymer matrices (excepting C-C) which are apparently not up to the thermal, tribological, and mechanical stresses of internal engine parts.

[Top Fuel F1]

Ti is effectively half as stiff as steel and a little under half the weight. To expand on how tedious it is to cast Ti.: One company which actually was started to exclusively supply Ferrari with Ti parts, and now supplies others as well, uses a proceedure which is probably what would be used to cast such a block:
1. They can make the casting pattern directly from CAD, which is used in the Investment Casting Process.
2. Use a gravity casting in a vacuum chamber.
3. The melt time is carefully calculated and the amount of material is critical.
4. One main problem is that the Ti solidifies extremely fast (a matter of some number of seconds)
5. Ti melts at 3,000 deg. F ,with the mould temp. probably about half that.
6. The melt doesn't retain much "super heat" above the initial melt temp. so you must get it into the mould quickly.
7. Small voids can form in the center of the casting because solidification is from the skin inwards
8. To eliminate these voids they do an "after cast" process called Hot Isostatic Pressing or "HiPing" (at 1,600 deg. F and at 15,000 psi in an inert gas chamber), which closes the voids.
9. Although they are working in inert gas I guess it's not perfectly inert. If Ti is over a 1,000 deg F it's surface tends to react with any oxygen present. The higher the temp. the more reactive.
10. The surface (maybe for 10-20 thousands) becomes oxygen rich which can allow flaws/weaknesses to form and propagate cracks.
11. To get rid of the oxygen enriched layer requires chemical milling of the surface which also producess a nice finish.

[david_martin]

Originally posted by Top Fuel F1
8. To eliminate these voids they do an "after cast" process called Hot Isostatic Pressing or "HiPing" (at 1,600 deg. F and at 15,000 psi in an inert gas vacuum), which closes the voids.

15,000 psi in an inert gas vacuum?;)

Still it is an interesting application of hot Isostatic pressing, which has traditionally been used in powder metallurgy as a method of improving the density of sintered products.

[desmo]

I'm sorry, I don't have a source handy, but I was under the impression that metal castings (and perhaps parts formed by other methods?) in F1 were routinely "HIPped." I think the fact that parts as complex as transmission cases and wheel uprights can be cast in Ti alloy, suggests that it would likely be possible to satisfactorally cast an engine block as well, but perhaps the process can't be scaled up.

[Cory Padfield]

Metal castings are routinely processed by HIP.

There is no particular reason why an F1 engine block couldn't be cast from a titanium alloy - there are no scaling issues.

One factor not mentioned in this thread is thermal conductivity. One reason why engine blocks are converted from cast iron to aluminium alloys is because the higher thermal conductivity of aluminium allows higher engine compression ratio. A typical cast Al alloy for F1 blocks is 357, with thermal conductivity of 150-160 W m K^-1. Titanium alloys have thermal conductivity of ~ 7 W m K^-1. This difference would require significant redesign of a block.

[Top Fuel F1]

Previous note edited:

Originally posted by Top Fuel F1
Ti is effectively half as stiff as steel and a little under half the weight. To expand on how tedious it is to cast Ti.: One company which actually was started to exclusively supply Ferrari with Ti parts, and now supplies others as well, uses a proceedure which is probably what would be used to cast such a block:
1. They can make the casting pattern directly from CAD, which is used in the Investment Casting Process.
2. Use a gravity casting in a vacuum chamber.
3. The melt time is carefully calculated and the amount of material is critical.
4. One main problem is that the Ti solidifies extremely fast (a matter of some number of seconds)
5. Ti melts at 3,000 deg. F ,with the mould temp. probably about half that.
6. The melt doesn't retain much "super heat" above the initial melt temp. so you must get it into the mould quickly.
7. Small voids can form in the center of the casting because solidification is from the skin inwards
8. To eliminate these voids they do an "after cast" process called Hot Isostatic Pressing or "HiPing" (at 1,600 deg. F and at 15,000 psi in an inert gas chamber), which closes the voids.
9. Although they are working in inert gas I guess it's not perfectly inert. If Ti is over a 1,000 deg F it's surface tends to react with any oxygen present. The higher the temp. the more reactive.
10. The surface (maybe for 10-20 thousands) becomes oxygen rich which can allow flaws/weaknesses to form and propagate cracks.
11. To get rid of the oxygen enriched layer requires chemical milling of the surface which also producess a nice finish.

[Top Fuel F1]

Another problem that you would have with a Ti casted block is that it is difficult to get much depth of hardness (microns rather than millimeters) on the surface regarding wear points. The hard skin is very stiff and the inner Ti is relatively flexable. That can be a problem if the part is highly stressed. Of course there are sleeves for the cylinders, unless your building a block like the F1 Cosworth engine. Also inserts for bearings. Ti readily tolerates sleeves and inserts. It's coefficient of expansion is a bit less than steel and some times that needs to be considered if you have a shrink-fit part that might have to run at high temperature. At this point I don't know how well Ti would take to ceramic coatings such a Nikasil.

[12.9:1]

Cory Padfield - writes

One factor not mentioned in this thread is thermal conductivity. One reason why engine blocks are converted from cast iron to aluminium alloys is because the higher thermal conductivity of aluminium allows higher engine compression ratio. A typical cast Al alloy for F1 blocks is 356, with thermal conductivity of 150-160 W m K^-1. Titanium alloys have thermal conductivity of ~ 7 W m K^-1. This difference would require significant redesign of a block.

Surly you mean the Cylinder-head.



.

[Cory Padfield]

12.9:1,

I do not mean cylinder heads. I am not sure if you take exception to my argument regarding thermal conductivity or alloy selection. My field is materials, so I am not an expert on engine functioning, but I believe I understand the concepts here. For spark ignition engines, one factor controlling maximum compression ratio is the heat transfer from the cylinders. If too much heat is retained, premature ignition occurs. Thus, aluminium's high thermal conductivity allows higher compression ratio. Regarding the alloy (investment cast D357), it was quoted in an article in JOM (a journal published by TMS, an affiliate of the American Institute of Mining, Metallurgical and Petroleum Engineers).

[12.9:1]

Regarding surface-hardening

this from - Racecar vol 5 no1



"Virtually any component that is manufactuerd from titanium can be surface-hardened using
DuraTi's 'Nitrogen Diffusion Hardening' process. NDH-processed titanium achieves a surface
hardness exceeding Rockwell 60C to a uniform depth of 250 microns (2.5mm or 0.01in)
yet the surface can be bent or dented without cracking or flaking."


This process is carried out with the part submerged in a "gas-fluidized bed" - fine ceramic
beads gently roiling with the passage of inert gas+nitrogen fed slowly from below.
All else temp, time, presser, - - proprietary.


Also - "Keronite," and the ever mysterious "Diamond like coatings" - which I believe cut piston
to cylinder friction to such a great extent, as to be instrumental in making 18,000 rpm
practical.


.

[12.9:1]

Cory


Without disagreeing, I would propose that a "cool" cylinder wall would promote heat transfer from the piston, reducing the chance of pre-ignition.


.

[Melbourne Park]

I am not an engineer, but isn't one of titanium's almost unique features is that it doesn't work harden? The other material being iron? I am not sure if this is relevent to engine blocks, but titanium would make safer aeroplanes, but for its cost.

[MRC]

A hotter cylinder wall will also heat the incoming charge, and will result in a loss in volumetric efficiency. A high temperature is sometimes of an advantage to reducing friction though. Gains or losses due to hotter or cooler cylinder temperatures have to be balanced against each other.

I think running an aluminum cylinder head would have larger benefits than converting to aluminum block. The exhaust valve temperature is closely related to the tendency for detonation. An aluminum head allows more even temperatures around the exhaust valve.

[Halfwitt]

Originally posted by Ferrari_F1_fan_2001
Titanium is 5 times more expensicve than steel and i think its 3 times stronger

Not only is it three times stronger, it attracts women to you, and if you buy some, good fortune will follow you always.

There is a lot of bollocks talked about Ti. Steel is more dense, stronger, and much stiffer. Aluminium is lighter and less stiff. Don't know how much it costs, but it is likely that the very strongest steels are more expensive.

Look on matweb before becoming entranced with this stuff.

[Melbourne Park]

Titanium also makes good watches; as a base metal, iits excellant for hyper alergenic usuages. I think its replaced stainless steel for human bone replacements, such as hips etc. In 1967 the America's Cup yacht Intrepid used a titanium mast. The material was then banned being labelled, rightly, an exotic material. Intrepeid trounced the Aussie yacht in the '67 defense, and the mast was an important feature in what was a revolutionary boat.

[VAR1016]

Originally posted by MRC
A
I think running an aluminum cylinder head would have larger benefits than converting to aluminum block. The exhaust valve temperature is closely related to the tendency for detonation. An aluminum head allows more even temperatures around the exhaust valve.

Of course the pre-war engineers were aware of this; whilst aluminium was often used, bronze was also popular. Most curious of all was the AJS company's plan to cast the 500cc" Porcupine" motorcycle's head from silver.

I am convinced that if steel of the appropriate quality can be cast sufficiently thin using this new explosion method, then it could offer the best compromise for blocks, between weight, structural integrity, heat transfer etc. for a short-life engine; I suppose that we must always be mindful that that a F1 engine is designed to last for about 2 - 3 hours!

Interesting that in another post a yacht mast was reportedly banned - for being of Ti "an exotic material". Well I suppose it is; but titanium is far more abundant than copper or lead in the Earth's crust

It is of course, the extraction that's the bugger!

VAR1016

[Cory Padfield]

12.9:1,

I agree that a cool wall is beneficial - thus, you need material with high thermal conductivity to allow the wall to cool.


Melbourne Park,

Work hardening, more correctly called strain hardening, depends upon chemical composition, crystal structure, and processing conditions. It is a highly variable property for any alloy, and just about any value can be obtained for any alloy. You mention increased plane safety - it is true that for a given strength level, it has higher fracture toughness than aluminium alloys, so it is possible to have a lighter vehicle for constant flaw resistance, or a more flaw resistant vehicle for constant mass. Cost does prevent more widespread usage. You are also correct that titanium is widely used in medical implants due to its outstanding corrosion resistance and low biotoxicity.


Halfwitt,

It is true that the highest strength steels (maraging steels, the only class that can compete with Ti alloys for specific strength) are VERY expensive, so the cost differential is essentially zero.

[random]

Titanium is a preferred material for racing suspension arms in many circle-track series. But there is the little issue of legality, titanium is of course totally and completely disallowed by the rules.

But, the only test most of the scrutneers run on these suspension bits is the old magnet-stick test. When they put a magnet next to your suspension bits, it'd better stick.

However, I've recently read in few different sources that some (most Nascar) teams have managed to acquire titanium suspension pieces that a magnet will stick to... Neat trick that.

Any clue how it's done?

[Halfwitt]

Originally posted by random
However, I've recently read in few different sources that some (most Nascar) teams have managed to acquire titanium suspension pieces that a magnet will stick to... Neat trick that.

Any clue how it's done?

Plated? Metal Sprayed?

[desmo]

I think that simply running liners- probably Al matrix MMC to match the thermal expansion of the MMC piston sets- would address the concerns about Ti's thermal conductivity or lack thereof.

[Ben]

Not really wanting to take a deep dive on this debate, I would like to point out that the statement about specific stiffness (Young's Modulus/density) is often misleading because dependant on the geometry of the part the measure of structural efficiency can be Young's Modulus/density^2 or even /density^3. This sort of criteria makes aluminium and titanium seem more attractive than steel.

If any of you have that Racecar Engineering article about B3 technologies' use of titanium you may rememeber a quote along the lines of sometimes titanium gives us a benefit over steel and sometimes it doesn't. I'm convinced that this comment was related to the variation in the structural efficiency criteria (is that a proper term Cory?) dependant on the part's geometry.

Ben

[Cory Padfield]

desmo,

An Al liner certainly would be a good choice. In fact, perhaps one could make a big step and have a Ti outer structure for engine + gearbox with a central Al combustion chamber, rather than the current "combined" condition.

Ben,

Structural efficiency criteria defines the non-materials related part of design - it is also known in the literature as structural index or structural efficiency coefficient. This is where one would see that an axial spring is more efficient than a torsion bar or leaf spring for a given material.

The material-dependent part of design is referred in the literature as material index, material factor, performance index, or merit index. This is where one would see that Ti is better than St for a given geometry.

[Melbourne Park]

Cory thanks for the enlightenment. As I also have a yachting background, the issue of "strain hardening" or work harding in my background is important. Looking at the America's Cup Class boats now, they push the edge of their constructions but the boats and rigging have to survive over a longer time and with a wider span of expected conditions. The idea that something can get weaker over a period of time is particully important to a yachtie: Murphy's Law says it will break, and O'Reilly's ammendment says it will happen at the worst possable time. If titanium was legal, it would be all over boats, because for a given weight its stronger than aluminium, and the belief is that it doesn't readily change its characteristics. In yachting, masts even change their stiffness characteristics over time as the alloy ages. The modern America's Cup Class boats have lots of aluminium and composite structures; Compsoite masts are used, and mast breakages are not uncommon; one of the Dennis Conner team's boats lost its keel recently, and sank. They are going to use the hull, saying the structural damage was minor as it hit soft mud on an angle in relatively shallow water. No lives were lost. But others feel they are taking a risk, as the internals of the hull are uncoated; and pressurised salt water from 25-30 metres down may get into the composite; and should the alloy skin which is attached to the composite, be effected by salt water, then over time delamination is a distinct possability. Many feel that Conner should prepare that boat as the #2 hull, as it may be suspect. But its normally the #1 hull that is fragile, and the more recent faster design, as it is the one which has a lighter design and is normally more fragile.

If titanium was allowed, those boats would cost a lot more.

I think titanium watches are great; they are hyper allergenic, and very light. They don't oxidise either.

Concerning the bronze, VAR1016 said:

Of course the pre-war engineers were aware of this; whilst aluminium was often used, bronze was also popular. Most curious of all was the AJS company's plan to cast the 500cc" Porcupine" motorcycle's head from silver.

I recall that GM did a lot of research into a "copper motor" or maybe it was a "copper head". It was described I think in the book "My Life with General Motors" or something like that, by one of the GM leaders, Alfred Sloan or something like, and he canned a very extensive project for a new engine as the dates for its approval kept going forward as they hit problem after problem. It was not an engineering book and I don't recall him much explaining the strengths and weaknesses of the design concept.

[desmo]

Tech Forum regular Andrea was nice enough to send me this photo he took of a Ti alloy-cased 043 variation on display in Ferrari's Maranello museum. I didn't recall this, and it does, I think, lend some credibility to the reports of similar developments being looked at more recently although one wonders why this never became standard practice in Maranello.



Ferrari is by far the most open of the F1 entrants when it comes to sharing the technology they have developed for F1 with the interested fans. I wish other teams had Ferrari's class and obvious self confidence in this regard. I find it ironic that some of the most secretive teams are the ones with obviously the least to hide! Delusions of grandeur I guess...

[Cory Padfield]

Thanks Andrea and desmo!

Can someone explain the chamber geometry we see? What is the shape we see in the upper part of each chamber? The lower part of each chamber seems to be a smooth, right circular cylinder that would define where the pistons move. Does this block need liners? Any evidence of coolant passages? Thanks for any help.

[Evo One]

Originally posted by Cory Padfield
Can someone explain the chamber geometry we see? What is the shape we see in the upper part of each chamber? The lower part of each chamber seems to be a smooth, right circular cylinder that would define where the pistons move. Does this block need liners? Any evidence of coolant passages? Thanks for any help.

It looks to me like the gaps between the inner cylinders are there to accept a complicated multiple liner - probably of Nicasil coated aluminium.

[random]

Steve Matchette mentioned during the practice coverage this morning that the Ferrari transmission is indeed made of cast titanium. But what he found especially fascinating is that it's only 10 inches long and doesn't appear to include a clutch.

He said he's yet to see a published photo of it, he said Ferrari have worked to keep it under very tight wraps.