Niobium's effect on steel or How I learned to love s35vn

Lapedog

Lapedog

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Dec 7, 2016
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Here is a cool video that explains what as little as 1/1000th niobium in steel can do to the alloy. I posted this in another thread but thought everyone should see it.

Just fast forward to 3 mins if you want to learn about the effect niobium has on steel's crystal grain structure.

https://m.youtube.com/watch?v=2ciPAsVTq6c *Edit* link should he working now.
 
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I hope Sir Martin is still with us in 2017. And yes, S35VC would have been a much nicer name.
 
Why s35vc? S35vanadiumcarbide?

*edit* oh I'm an idiot s35vanadiumcolumbium!
 
Cool video. I thought CTS-B70P sounded interesting for the Niobium content. The mule I have in it from Spyderco has been great for my use, think they're still available.

Any other cutlery steels besides S35VN, S110V, and B70P use Nb?
 
I was curious about niobium as an improvement/replacement to vanadium.


Turns out its just not as effective as vanadium in terms of wear resistance hence why its used to bring more balance to s35vn as a better overall knife steel from s30v trading some of that wear resistance for toughness, ease of sharpening and more corrosion resistance.
https://www.crucible.com/PDFs\DataSheets2010\dsS35VNrev12010.pdf

Of course s30v and s35vn should be very close in wear resistance if all variables are accounted for which they never are :p

Vanadium does the same thing described in the video and is also able to limit grain growth in small amounts such as aus8, vg10, 80crv2, 8cr13mov etc. These steels all have a low amount of Vanadium for the purpose of grain refining and improved response to hardening when heat treating( even transformations throughout the piece)


Also the steel being described in the video is not knife grade stuff. Super soft (0.03-0.05 Carbon), just iron really (austenitic/ferritic) , No martensite ( the structure that makes knife steel hard) and 0.0095 niobium,; just enough to stabilize the desired structures in absence of carbon to strengthen the alloy. This is good for welding pipelines, nothing us blade geeks care about :D
x80 steel is also cheap stuff compared to knife steel.

Basically the mechanics he describes in the video are a little different for s35vn which is focused on using the extra niobium for wear resistance as NbC, Niobium carbide. Its used as a carbide substitute for vanadium to keep the total carbide volume similar to s30v and a grain refiner second.

It would be like reducing the sugar of a soft drink but then using another artificial sweetener to keep the total sweetness up but reduced calories ;)

here's more reading about the subject for more the knife nerds in us all :D

What is a grain boundary?
https://en.wikipedia.org/wiki/Grain_boundary

How Microalloying improves strength?
https://en.wikipedia.org/wiki/Grain_boundary_strengthening


How is the grain growth is reduced by Niobium/vanadium/chromium/molybdenum?
https://en.wikipedia.org/wiki/Zener_pinning

VC, Vanadium Carbide versus NbC, Niobium Carbide
http://www.matweb.com/search/DataSheet.aspx?MatGUID=9b8cf5d9e301463999f87de3d6744b94

http://www.matweb.com/search/datasheet.aspx?matguid=e6142d5f5c1247cbb4ce84f74201b23e

vanadium is harder :)
 
Cutting sugar or artificial sweeteners is bad for your knife !!!

The use of Cb [yes I'll use columbium, the original term for us metallurgists] ! in low carbon steels improves things in austenite which will carry on into the other structures when cooled .
One advantage of Cb over V is that while small amounts of V concentrates at grain boundaries to slow grain growth , Cb tends to be throughout the grain , adding strength and toughness.

My newer Sebenza has the advantage of a well balanced mix of V, Cb, and other carbide formers . Tougher, easier to sharpen , etc, my favorite of the 'powder steels'.
 
DeadboxHero said:
I was curious about niobium as an improvement/replacement to vanadium.


Turns out its just not as effective as vanadium in terms of wear resistance hence why its used to bring more balance to s35vn as a better overall knife steel from s30v trading some of that wear resistance for toughness, ease of sharpening and more corrosion resistance.
https://www.crucible.com/PDFs\DataSheets2010\dsS35VNrev12010.pdf

Of course s30v and s35vn should be very close in wear resistance if all variables are accounted for which they never are :p

Vanadium does the same thing described in the video and is also able to limit grain growth in small amounts such as aus8, vg10, 80crv2, 8cr13mov etc. These steels all have a low amount of Vanadium for the purpose of grain refining and improved response to hardening when heat treating( even transformations throughout the piece)


Also the steel being described in the video is not knife grade stuff. Super soft (0.03-0.05 Carbon), just iron really (austenitic/ferritic) , No martensite ( the structure that makes knife steel hard) and 0.0095 niobium,; just enough to stabilize the desired structures in absence of carbon to strengthen the alloy. This is good for welding pipelines, nothing us blade geeks care about :D
x80 steel is also cheap stuff compared to knife steel.

Basically the mechanics he describes in the video are a little different for s35vn which is focused on using the extra niobium for wear resistance as NbC, Niobium carbide. Its used as a carbide substitute for vanadium to keep the total carbide volume similar to s30v and a grain refiner second.

It would be like reducing the sugar of a soft drink but then using another artificial sweetener to keep the total sweetness up but reduced calories ;)

here's more reading about the subject for more the knife nerds in us all :D

What is a grain boundary?
https://en.wikipedia.org/wiki/Grain_boundary

How Microalloying improves strength?
https://en.wikipedia.org/wiki/Grain_boundary_strengthening


How is the grain growth is reduced by Niobium/vanadium/chromium/molybdenum?
https://en.wikipedia.org/wiki/Zener_pinning

VC, Vanadium Carbide versus NbC, Niobium Carbide
http://www.matweb.com/search/DataSheet.aspx?MatGUID=9b8cf5d9e301463999f87de3d6744b94

http://www.matweb.com/search/datasheet.aspx?matguid=e6142d5f5c1247cbb4ce84f74201b23e

vanadium is harder :)
Click to expand...

DBH, I love your posts on steels. Very informative but easy for a noob like me to understand :D
 
hahaha glad I can help, I remember when I was first learning and reading the steel gurus talk here and I just couldn't understand what they were talking about because of all the special vocabulary. I was like " dang it, If I ever learn whats going on I'll make it easier to understand for the next guy!" lol :D

Im no guru but I am always learning :D
 
The carbon - metal bonds [very high for Vanadium] means that the time and temperature to break those bonds in HT are high .Austenitizing times are may be 45min with appropriately high temperatures.
And yes we can play games as in Wootz where we never totally dissolve the VC ,producing a very wear resistant blade.
On the other end of the scale the weaker carbide bonds found with Fe and Cr are found in many tools steels - easier to HT !
 
I am aware that the demonstration in the video is simplistic at best. I mean it was described with paper and tape. I just thought it would be interesting to sort of point out what even a tiny ammount of Niobium does. The ammount put in s35vn is much more than 1/1000th as described in the video and in the quantities available in s35vn contribute to abrasion resistance as well.
 
Micro-alloying has been around since 1960 at least . Boron additions of as little as .0005 % has been used back then !!
 
Niobium is the main "beta stabilizer" element in the best beta titanium alloy I've been using to forge swords. The alloy is 10% niobium! Niobium is very heavy and you can feel the extra weight when hefting the bar stock. Among other wonderful things, it protects the sensitive titanium from atmospheric gas contamination when hot forging in the open air all day, like built-in flux.

The titanium alloys used in human medical implants now often use 7% niobium instead of 4% vanadium, eliminating the toxicity of vanadium and making a more wear-resistant and stronger alloy for moving joints.

Titanium absolutely loves niobium.

50/50 TiNb alloy is also a superconductor.


Yes Mete, the sword ti alloy is also "micro-alloyed" with about 0.4% iron! :D
 
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