san mai with tungsten carbide

[Natlek]

What do you think ? This are 1.2mm thick /solid tungsten carbide /knives for paper industry .You have no idea how sharp they are ,they make my knives to look dull ...hair popping dull
Core tungsten on sides soft stainless ? No need to HT ,nothing.......... just grind them ? Or stainless steel for core and tungsten carbide on sides ...no scratch knife
Seriously , what do you think about this ? Not for chopper , but for light cutting task why not ?

 

[Drew Riley]

I think you'll have a pretty tough time forge welding tungsten carbide.

 

[Natlek]

I think you'll have a pretty tough time forge welding tungsten carbide.

Even with thin layer of something like bronze between tungsten and steel ? Something like brazing them together ? What do you think ?

 

[CallumRD1]

You could certainly braze stainless steel to the tungsten carbide but I'm extremely skeptical that the knife would be usable. Tungsten carbide is so brittle that you'd need a fairly obtuse edge angle to have it survive. That being said, I'd love to see it tried. I don't expect it to be practical, but for the sake of an experiment it should be attempted!

 

[Stacy E. Apelt - Bladesmith]

However you do it it will be really hard (pun intended) to grind.

 

[Sam Dean]

We braze and grind tungsten carbide at my workplace (we manufacture milling cutters & reamers), and a few guys here have tried many times to do this same thing.

When brazing strips together side by side (to make a knife blade), the steel backer and carbide expand and contract at different rates, which cause the carbide to crack. However, I don't think anyone has tried a san-mai lamination.

Assuming a successful braze is possible, the next issue is grinding. The carbide is ground with diamond wheels under oil. Grinding into steel causes them to load up and stop cutting. You would need to make the outer layers of a san-mai from a very hard steel, like Rex-121, in order to grind both together. We will sometimes use T15 at 68-70Rc for tool bodies, but even that is on the soft side for a diamond wheel.

Those are just the issues we've had - if you can figure out a way please share!

If you want something insanely sharp and brittle, maybe make a blade from tungsten carbide with a polycrystalline diamond edge?

 

[A.McPherson]

You might be able to braze it by heating it slowly in an kiln/oven, then very slowly cooling it down... With added time the expansion rates might be mitigated.

I've seen people making mokume game with this method, and I bet it would work for your purpose as well:. Take your stainless steel drill holes in the corners, put your carbide in the center, with whatever brazing material your going too be using in between. Put it all together and use bolts in the holes inyin stainless and apply lots of pressure.

Heat it up, brazing melts, pressure keeps it together and squeezes out excess braze material.

 

[Natlek]

You could certainly braze stainless steel to the tungsten carbide but I'm extremely skeptical that the knife would be usable. Tungsten carbide is so brittle that you'd need a fairly obtuse edge angle to have it survive. That being said, I'd love to see it tried. I don't expect it to be practical, but for the sake of an experiment it should be attempted!

Well , because it is so brittle i want to try to make sandwich. TC are most weak on side loads so using knife to cut soft things will work ... About angle , this blade is about 0.5 - 0.6 thick behind edge /i used caliper to measure/ and 18 degree angle per side , it was little tricky to hold this thing and not to cut my self but i cut this copper wire using that blade as hammer , no damage to edge . . .That was not that bad geometry for knife edge ? Hey it will cost me my time only why not to try ? I have lot of this kind of blade to try ......when they wear from resharpening to some Dia. they are not usable on machine so they give to me for free ......

 

[Natlek]

However you do it it will be really hard (pun intended) to grind.

It will need very little grinding on tungsten carbide Stacy .It is only 1.2mm thick so plan is only little of TC to be exposed on edge .Most i will grind stainless from sides .Anyway next month I have private trip to Germany so i plan to buy one CBN belt ........

 

[Natlek]

We braze and grind tungsten carbide at my workplace (we manufacture milling cutters & reamers), and a few guys here have tried many times to do this same thing.

When brazing strips together side by side (to make a knife blade), the steel backer and carbide expand and contract at different rates, which cause the carbide to crack. However, I don't think anyone has tried a san-mai lamination.

Assuming a successful braze is possible, the next issue is grinding. The carbide is ground with diamond wheels under oil. Grinding into steel causes them to load up and stop cutting. You would need to make the outer layers of a san-mai from a very hard steel, like Rex-121, in order to grind both together. We will sometimes use T15 at 68-70Rc for tool bodies, but even that is on the soft side for a diamond wheel.

Those are just the issues we've had - if you can figure out a way please share!

If you want something insanely sharp and brittle, maybe make a blade from tungsten carbide with a polycrystalline diamond edge?

Sam , grinding is not problem ...... brazing is problem .Do you have some experience with silver brazing alloy paste ? Look to me that this is best way to try this ?
https://www.fusion-inc.com/brazing/alloys-and-paste/carbide/

Brazing temperature considerations Silver brazing alloys specifically recommended for the brazing of tungsten carbide operate at temperatures that are typically in the range 670 - 730ºC whereas brass needs to be raised to around 930ºC

 

[Stacy E. Apelt - Bladesmith]

It will need very little grinding on tungsten carbide Stacy .It is only 1.2mm thick so plan is only little of TC to be exposed on edge . Most i will grind stainless from sides .Anyway next month I have private trip to Germany so i plan to buy one CBN belt ........

OK, if you say so. I'll wait and see how it turns out. I am mostly interested on how you will make it into a knife shape.

 

[Bigfattyt]

I used to work with tungsten carbide. Very large cubic hydraulic presses (for making diamond drill bits for oil drilling).

Tungsten carbide is heavy, dense, and brittle. When the press would blow up at a million pounds per square inch, we dealt with lots of tungsten carbide shards. Sharp as shattered glass.... and just as brittle.

I've cut my self wirh it. Even cutting cardboard with it, it would chip and fracture.

It is terribly expensive stuff to machine...compared to even super steels.

 

[Natlek]

OK, if you say so. I'll wait and see how it turns out. I am mostly interested on how you will make it into a knife shape.

OK, if you say so. I'll wait and see how it turns out. I am mostly interested on how you will make it into a knife shape.

I have water jet and laser fiber in hand to try .I don t think that shaping would be problem ...welding,brazing is problem for now .

 

[Sam Dean]

Sam , grinding is not problem ...... brazing is problem .Do you have some experience with silver brazing alloy paste ? Look to me that this is best way to try this ?
https://www.fusion-inc.com/brazing/alloys-and-paste/carbide/

We don't use the all in one paste. It's been tried, but wasn't as reliable (for our use).

We use this flux: https://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/Fluxes/Stay-Silv-Black-Flux.aspx

...and this braze compound: https://bellmanmelcor.com/product/a-50n in both 1/16'' wire and 1'' X 0.005'' strip. For what you want to do, the strip would be best. We cut it into smaller pieces with scissors.

We use oxy-propane torches for most of the smaller stuff, and oxy-acetylene for tools with more mass.

Too bad you're not in the US - I'd send you some to play with.

 

[Sam Dean]

I have water jet and laser fiber in hand to try .I don t think that shaping would be problem ...welding,brazing is problem for now .

Do you have access to a wire EDM? That's by far the fastest way to cut any complex shape. Waterjet cutters can do it, but only with diamond abrasive - the standard garnet isn't hard enough. The laser will burn a significant area that will have to be ground away - best to stay away from one.

 

[Natlek]

Even cutting cardboard with it, it would chip and fracture.

It is terribly expensive stuff to machine...compared to even super steels.

There was many type of TC .....This one are specially made for cutting corrugated board , and are about 80 hrc hardness .Again , i know with what I have to deal . . . ..
https://www.tcblade.com/carbide-kni...ard/bhs-slitter-oem-carbide-blade-240-32.html
This is walnut ...............

Probably I can spend rest of my life cutting cardboard with this .....before it get dull

 

[Natlek]

Do you have access to a wire EDM? That's by far the fastest way to cut any complex shape. Waterjet cutters can do it, but only with diamond abrasive - the standard garnet isn't hard enough. The laser will burn a significant area that will have to be ground away - best to stay away from one.

Yes .... laser , water and EDM all in one place in my friend shop .I forgot about EDM .....

 

[Natlek]

We don't use the all in one paste. It's been tried, but wasn't as reliable (for our use).

We use this flux: https://www.harrisproductsgroup.com/en/Products/Alloys/Brazing/Fluxes/Stay-Silv-Black-Flux.aspx

...and this braze compound: https://bellmanmelcor.com/product/a-50n in both 1/16'' wire and 1'' X 0.005'' strip. For what you want to do, the strip would be best. We cut it into smaller pieces with scissors.

We use oxy-propane torches for most of the smaller stuff, and oxy-acetylene for tools with more mass.

Too bad you're not in the US - I'd send you some to play with.

Thanks Yes , that strip are best for what i want to do .............I will make some call to see if i can find that .I think i have idea where can i found them .

 

[Natlek]

You might be able to braze it by heating it slowly in an kiln/oven, then very slowly cooling it down... With added time the expansion rates might be mitigated.

I've seen people making mokume game with this method, and I bet it would work for your purpose as well:. Take your stainless steel drill holes in the corners, put your carbide in the center, with whatever brazing material your going too be using in between. Put it all together and use bolts in the holes inyin stainless and apply lots of pressure.

Heat it up, brazing melts, pressure keeps it together and squeezes out excess braze material.

Thanks , probably that is best way to do this .....................

 

[Bigfattyt]

Will be interested to see what comes of this.

We had buckets and buckets and buckets of scrapped shattered Tungsten at my old job. But even In the shattered state it was valuable. We would send it back to be recycled.

We braze and grind tungsten carbide at my workplace (we manufacture milling cutters & reamers), and a few guys here have tried many times to do this same thing.

When brazing strips together side by side (to make a knife blade), the steel backer and carbide expand and contract at different rates, which cause the carbide to crack. However, I don't think anyone has tried a san-mai lamination.

Assuming a successful braze is possible, the next issue is grinding. The carbide is ground with diamond wheels under oil. Grinding into steel causes them to load up and stop cutting. You would need to make the outer layers of a san-mai from a very hard steel, like Rex-121, in order to grind both together. We will sometimes use T15 at 68-70Rc for tool bodies, but even that is on the soft side for a diamond wheel.

We would grind on either lap plates wirh diamond dust mixed with water. Also centereless grinding also with water. We had to grind and finish both he carbide substrate and policrystaline diamond surfaces.

I do miss working there and having access to all kinds of equipment and smart engineers.