Ni-Cr alloy for knife making, any ideas?

H

hammerfall

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Oct 2, 2010
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recently, i had chance to deal with a ni-cr age hardening alloy. it composit with 55%of Ni and 40% of Cr. the heat treatment of this alloy had invoved high temperature solution, and age hardening arround 650°C. which is relatively easy to do compare to most toolsteel that require cryogenic process.

oringinally this alloy was used for ball bearing tools on submarines during cold war era. now i am thinking that if this thing can be used for knife making. good toughness under hardness above hrc57 with exellent wear resistance, and unmatched corrosion resistance. it seems a perfect knife making alloy to me.

so what do you think? good or bad, any information is welcome.

btw, i am new to BF. here i give my greeting to every person whose knives are their mistress.
 
english is not my native tongue. so please bear this with me.

the hardern mechanism of this alloy is percipitation hardening. or call it dispersed phase hardening. when cold roll adopted, Ni3Al phase's precipitation and growth.the line of dislocation will twist and circling arround the growing ni3al. caused a dislocation loop on each precipitation phase. if i remember right such mechanism called Orowan mechanism. this mechanism greatly increasing the wear resistance of the alloy. for my own experience, this alloy holds way better wear resistance than most of the tool steel i have seen under same working hardness.

also unlike carbon-fe alloy which majorly based on tempered marstensite. which feature that the toughness reduces along with temperature drops. This is so called cold brittleness phenonmenon. this ni-cr alloy is based on austenite, mean well there is no cold brittness phenonmenon. it will meet requirment for the extram cold condition.

the best part for this thing is that it seems never rust. i tried salty water, alkali water, this thing just don't rust. at least nothing i can see. well, it has 40% cr in its alloy, i guess that explains everything lol.

imo its just meets everything a knife desired.
 
Make one and tell us how you like it !! Do you have an alloy number for that alloy ? It must be very expensive .
Welcome to the forum.
 
I have been looking into non-ferrous blade materials recently mostly cobalt based alloys, and find the prospect intriguing. Do you have any data, composition, wear resistance, toughness etc.
 
The alloy number is GNiCr40Al4. i am not sure if you can find its US version. i believe it was first a soviet production for ball bearing tools under non-magnetic conditions back in 1980s. my friend is making one knife from the alloy. and yeah it is expansive since there is 55%Ni, i think its something arround $61 per lb.

i am not sure about the detail of manufacture process. but the composition of the alloy is 55%NI, 40% Cr, 4%Al. the rest 1% remain unknown by my knownlodge.
 
Nebulae said:
I have been looking into non-ferrous blade materials recently mostly cobalt based alloys, and find the prospect intriguing. Do you have any data, composition, wear resistance, toughness etc.
Click to expand...

I'm interested in non-ferrous knife materials too.The stellite are typical cobalt based alloys that may be applicable to knife, but i think stellite alloys is very difficult to get combination of hardness and toughness.for example, the hardness of stellite 100 is about hrc61-66,but it is too brittle, and stellite 6k get better toughness ,but it is too soft.
 
Out of curiosity, why do you want a non-ferrous knife blade?

The high alloy stainless steels are tough, hard, corrosion resistant,can be worked with normal knife shop equipment, and are affordable.
 
i think this alloy's wear resistance are far supperior than any ferrous alloy with same hardness and toughness. meanwhile it will hold better edge as a knife. the corrosion resistance of Ni-Cr alloy is something ferrous stainless steel cannot compete with. beside it has non-magnetic, non cold brittleness phenonmenon all together. make it exellent for special use under extram conditions.

i think it is also able to work with most knife shop equipment. few hours of 600~650°C controled age hardening is far easier than steel which requires cyrogenic process. and "affordable" is tricky here, i believe it is always depends on how much you needed something.

and yes, it is expansive. as i said before, this alloy wasn't oringinally designed for civil using, so most of its ability will not shine in common folks hands. but if you constantly working under water, causally working in extramly cold environment，or requires to avoid magnetic matiral; this alloy will fits for these situations. if shit ever hits your luck and you just have to by pass the magnetic sensoring device on mines or the hostile security system, this thing will stick with you lol.

anyway, this thing is not for most people's everyday life.
 
btw, the forging process of this alloy is similar to those of high alloy steel, and solution temperature is just above 1200°C.

if cold roll is avaliable, the hardness can hits up to over 67 hrc with greatly increasing in wear resistance.
 
since there are more than a few people wants to know the toughness after heavy cold work deformation. i am requested to explain it with a little detail.

you do not need to worry about toughness too much at hrc 67. cold work deformation will cause large degree of dislocation accumulated into sub-grain boundary. once recrystalized during the aging process, it will tremendously refine the grain size. the hardness increasing after coldwork is mostly due to the grain refinement, so there will not be much problem for toughness at hardness level at 67.

this is also one supperior advantange for interphase precipitation hardening alloy compare to tempered matensite/bainite type alloy.

this alloy can be hot forged as well. but caution MUST be taken carefully to avoid cracking.
 
BTW, guys - I've made arrangements to test some of this metal. I will let you know what it does.
 
I'm trying it out as well. I read up on the precipitation hardening Nickel-chrome super alloys. It's very interesting stuff. Almost a poetic science.
 
Nebulae said:
Is there a data sheet available, there are just so many questions
Click to expand...

i do not have any english data sheet in detail avaliable here, but you might be able to check US jet-fighter's landing gear, shaft on height-meter...etc. you can find quiet similarity between two alloy.

try those jet fighters that based on aircraft carrier, those type usually has better landing gear.
 
Do you mean 90% reduction or reduce to 90% ?

For example -

90% reduction = roll a 25mm bar to 2.5mm

reduce to 90% = roll a 4mm bar to 3.6mm
 
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