What is in maraging steel?

[telkanuru]

You would also have to look at fracture patterns. Titatium or titanium alloys may not break as cleanly...

[Purple Fencer]

Originally Posted by telkanuru

You would also have to look at fracture patterns. Titatium or titanium alloys may not break as cleanly...

Are you referring to the thought that maraging steel breaks more cleanly than carbon steel?

I used to think so, but Dan Dechaine has said that the fracture patterns on a maraging blade are the same as on a carbon steel one.

The reason that maraging steel blades are required at FIE events isn't because the breaks are flat (they aren't necessarrily....and I've seen flat carbon steel breaks and spike FIE ones) but that because they break less frequently, and thus it lessens the possibly injuries from broken blades (i.e. less Smirnovs).

[telkanuru]

No, no, I know the 'FIE breaks more cleanly' is probly an urban legend. However, the types of steel used in blade construction seem to have a higher tendancy to break cleanly, FIE or non FIE. I do not know if this is the case for titanium or its alloys.

[DJ Apostrophe]

Originally Posted by howtobrew

What are non-FIEs made from??
I don't know, I would imagine that they are spring steel, but the websites don't say. I should see if there are any broken blades at the club I could do an xray analysis on....

The company I work for ( Innov-X Systems http://www.innovxsys.com ) makes portable XRF analyzers ... I'll see if I can grab a unit before I go to club tonight and shoot a bunch of blades... I'll post the results when I can.

-w

[howtobrew]

Hmmm, good questions all...

1. A composite metal blade is do-able, by co-extrusion, or explosive cladding, or by friction welding. You can't fusion welding (MIG, TIG) dissimilar metals because you get brittle intermetallics or non-mixing and it breaks. Friction weldind is different in that you spin two rods in opposite directions and bring them together under pressure at room temp. The friction heats and plastically flows the metals together, creating a metallurgical bond without any actual mixing of the metals. Neat process really, its how we joined titanium tubing to stainless steel tubing on the International Space Station.

2. Aluminum has the same modulus problem as titanium. You can make very strong alloys of aluminum: aluminum-lithium and aluminum-beryllium come to mind, but the problem is brittleness. When you take a low modulus material and make it very strong/stiff, you have to make it brittle too, that's the trade-off.

3. Longevity...
Well, after combing thru the Aerospace Structural Metals Handbooks, I was astounded to discover that I could not find a number for Ti-6-4 Fracture Toughness, nor one for Beta III titanium alloy. (As a rule, you can never find the one number for the exact condition you are looking for...)
But to address the answer from first principles, the longevity of titanium alloy blades would probably be less than carbon steel blades because the maximum strength of Titanium alloys is about 2/3 or less than that of steel. Now you wonder, "But I have heard titanium is stronger than steel...?" Yes, but on a per weight basis. If you had two blades that were the same weight, the titanium one would be twice as thick, and therefore 4/3 as strong.
And, because the tensile strength is 2/3, generally the fatigue strength is 2/3 for the same applied stress.

Beats working,
John

[howtobrew]

I also happen to be a fractographer/failure analyst.

The fracture surface shape will depend mostly on the applied stress and the type of propagation, ie. is it a corrosion failure, stress-corrosion cracking, fatigue, overload, creep, embrittlement, intergranular, transgranular, etc.
What I mean is how did the crack initiate, and how did it propagate? If a material is brittle, chances are that there will be lots of surface micro-cracks that will eventually join up to create a macro crack that propagates to failure. A Ductile material will probably only have a single initiation site.

A ductile crack, in an overload or "catastrophic" failure (ie. WHAM) will often have a 45 degree fracture surface relative to the applied force. A more brittle fracture will tend to have a more 90 degree fracture surface in an overload failure. (But it depends).

Outside of a overload/catastrophic failure, the crack would propagate by fatigue (cyclic load) or sustained loading. Our blades would propagate from low cycle, high stress fatigue. Though fatigue tends to mean a consistent cyclic loading, which not exactly the case here.... Anyway, a fatigue crack will have a crescent pattern radiating outward from the initiation site, and the fracture surface will propagate usually perpendicular to the applied stress.

A really brittle metal will break like glass and give off shards. I have seen high strength stainless steels and titanium alloys behave that way in cold temperatures.
Hope this helps,
John

[DJ Apostrophe]

Well... I grabbed an instrument on the way out the door friday night and brought it to club... when I learned something very valuable (for about the tenth time) ... Don't take things out of the R&D office and expect them to work... the settings are all changed and it won't play at all... I'll fix it and get some readings when I can.

-w

[Genjuro]

Does (small) temperature differences also influences the
breaking chance of blades? Say, between winter (assuming an indoor temp = 17 C/44,6 F) and summer (indoor temp = 25 C/ 77 F).
My fencing coach seems to thinks so,
but I think that those differences are to small to be significant...

[howtobrew]

It depends on the alloy. The most cited case is the Liberty ships of WWII. The high silicon containing steel weldments of those ships cracked in the cold temperatures of the North Atlantic and the ships literally broke apart. This phenomena is known as the Glass Transition Temperature, where it goes thru a definite ductile to brittle transition. Maraging Steel with its high nickel content and low carbon should not be more prone to breakage due to typical cold temperatures. Antartica maybe, but usually not. Most similar alloys are rated for cryogenic work.

[smeric28]

i started this thread to see what rumors people had herd. i know what maragings steel is, i'm a technology major. the high nickel content decreases the occurance of microfractures from impacts. microfractures are where big fractrures begin. the alloy was originaly invented in the 60's for applications for high strength steel in low temperature enviroments.

[D+F+P=Hadouken!]

question: can maraging steel rust? Also, is the black coating on a vniti blade to prevent rust?

[ReverseLunge]

No it cannot rust since it has little to no carbon content and the coating on the blade is to prevent tarnishing.

[smeric28]

Originally Posted by ReverseLunge

No it cannot rust since it has little to no carbon content and the coating on the blade is to prevent tarnishing.

not true. what rusts in steel any kind including maraging is the iron. maraging steel is naturally more resistant to rust because as the steel ages it forms a clear oxide barrier that impedes further rust. the black on a viniti blade could be a couple of things i suspect it's black oxide, black oxide can prevent some rust when combined with an oil dip. it could also be the finish left from oil quenching. both finsihes do a moderate job of retarding rust on all iron.