Effects of cold temperatures on Sport Fencing equipment blades 1

[Phraedrique]

There has been a lot of discussion in the Sport Fencing community about the effects of relative cold temperatures on fencing blades and the need to "warm them up" using friction to 'Room Temperature' prior to use. The temperatures that I am referring to are between -20 degrees F and 50 degrees F. Many fencers claim that if the blades are not warmed up thathtey become brittle and are more prone to breakage if they are not warmed up.
The general kinds of stresses applied to these blades are impact (blade to blade contact, blade to guard contact and blade to 'target' contact) and flexing in a single plane.

Steels used in these blades are either of Maraging steel or of — 45Si7, 45Si Cr Mo, 45 XH2 MFA.

My assumption is that these temperature ranges would have minimal effect tothe ductility of the metals, but is has been a LONG time since my failure analysis class, and I was never that good in my chemestry. Any thoughts on this would be nice.

 

[EdStainless]

If I ever get set up in my new office I'll look it up for you.
It isn't impossible that freezing would be cold enough to cause a noticeable reduction in ductility. But I thought that these grades had better toughness than that.

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Plymouth Tube

 

[CoryPad]

In general, maraging steels don't have ductile-to-brittle transitions like traditional steels. Negative 20 [°]F isn't that cold for a high-performance steel, so I wouldn't be concerned.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Phraedrique]

Thanks for the info. How would I present this to non-technical people that are convinced that they must "warm up" their blades prior to using them? Should I even bother?

 

[btrueblood]

Challenge them to a duel (for money) outdoors on a below-freezing day. Collect cash and become filthy rich.

 

[Phraedrique]

Hummm.. the duel idea might prove dangerous if I'm wrong... But seriously on a related note, should there be some expectation of greater failure due to cold if the weapon has been strained beyond its ?placticity? limit (sorry my knowledge of materials is leaving me here) where the blade took a permanent bend and then was bent back to its original form?
And yet another question - Is there a way to VISIBLY determine impending failure of a blade due this kind of damage? I have been told to look for 'whitening' of the afffected area that might show multiple microfractures or loss of ?structural integrity? Most weapons will be subjected to multiple ?deformations? of this kind prior to final catastrophic failure.
Sorry, I;ve been working as an IT tech for 10 years now and my old vocabulary on mterials and testing terms have long ago left me.

 

[TVP]

The other grades mentioned besides the maraging steel are martensitic "spring" steels, which will definitely have a ductile-to-brittle transition somewhere between 50 F and say - 50 F. The exact transition will depend upon chemical composition, processing history (quenching & tempering, grain size, etc.), presence of inclusions, etc. I certainly would not use these steel blades at a temperature below freezing, and would agree with the practice of warming them to room temperature.

 

[EdStainless]

One of the uses for Co containing maraging steels is arrestor hooks on jets that land on aircraft carriers. I trust that these alloys will have good strength and toughness across a wide range of temperatures.
The same cannot be said for high carbon spring steels. Having spent some time in the spring wire business I can tell a couple of stories of spring makers that took coils of wire off of trucks in the winter and went straight into production. Shattering spring steel is hard on tooling.

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Plymouth Tube

 

[Robertmet]

Back in my fencing days we always fenced indoors and I don't think ever less than 50 F. The broken blades I examined were of 9255 .The cause of failures were from dirty steel and fatigue failures initiated at the inclusions , or , fatigue failures due to nicks in the blades from beats. Clean steel and chamfered or rounded corners would have greatly reduced failures....Most likely someone 'heard' that steel is brittle at lower temperatures !! Lets design and sell blade warmers !! I knew fencers who carried rabbits feet, wore lucky shoes , etc, etc.

 

[Robertmet]

I should add that it is the responsibility of the fencer ,the instant he makes a hit,to relax his arm. Failure to do so has resulted in many broken blades and injuries !!!

 

[Phraedrique]

"Most likely someone 'heard' that steel is brittle at lower temperatures !! Lets design and sell blade warmers !!"
This was my whole question from the beginning of the thread. I've seen fencers take their blades from their blade bags and proceed to "warm up" their weapon by rubbing it with an old piece of towel, all the while proclaiming that this is the only way to ensure the blade doesn't shatter.
Would you recommend the judicious use of a file on the non-champhered blades to reduce failures?