Cracked Furi Cleaver 3 times...

[Luke]

Hi All,

Don't know if I am doing something wrong (I am an engineer after all) but I have just cracked my 3rd Furi Cleaver.

1st one cracked after one year of use. It cracked in the middle on the cutting edge. That was replaced for no charge by the local Furi distributor, and the replacement cracked towards the end of the cutting edge about 3 months later. That one was also replaced for no charge. The replacement for that one last about 4 months and it has now cracked, in the middle but on the spine (not the cutting edge).

The knives are hand washed and treated well. The only thing I can think of is that they are stored on a magnetic knife rack. But so are my other knives and this is first time I've had a problem. One knife crack I can understand - 3 in a row......hmmm. Well, so far Furi have just replaced the knives with no questions asked (can't complain about that). My furi chefs knife, while not my favorite, is heavily used and has not cracked.

Your thoughts?

Luke

[Lisa Shock]

What kind of cutting board are you using?

[Joe Blowe]

It wasn't stated, but I have to ask: Are you using this "cleaver" to chop through large joints of meat or other hard/bony substances?

The Furi #106, as seen in your photo, is advertised as a Chinese-style cleaver meant to chop vegetables and so on...

[paulraphael]

Even if you're abusing the bejeezus out it, that's not normal. If you used a vegetable cleaver to hack through bones, you'd expect to either chip or dent the edge. A blade that cracks like that is deffective. Three in a row suggest bad knifemaking. You can either buy a better one, or keep enjoying the free Furis til the well runs dry ...

[Chris Hennes]

What paulraphael said: with a crack like that, the way you treated the knife is completely irrelevant (unless you've been leaving it in your furnace, etc.). Three different knives, same manufacturing defect? That's ridiculous, get your money back and take it elsewhere.

[David A. Goldfarb]

If one were to use a mallet on the spine of a vegetable cleaver to hack through bones (which would be perfectly acceptable technique with a meat cleaver), that could crack the spine.

[Luke]

Hi Guys,

The clever has only ever been used on a wood chopping block, and since cracking the 1st one I have been pretty cautious with the 2nd and 3rd. I have not cut any bones with this particular one.

As far as I am aware, I have never noticed the cracking occurring during use, only in storage (taking it from the magnetic rack and then finding it cracked).

Luke

[budrichard]

Cleavers and Chinese Chef are two different knives but Furi advertizes that this one can be both. Wusthof makes cleavers and a Chinese Chef knife and i suspect the heat treat is very different. One wants a cleaver to have less hardness and tensile strenth while a Chinese Check knife made for just cutting, should be harder for a finer edge and edge holding.

The knife you pictured has not suffered any plastic deformation but exhibits a classic brittle fracture except the entire blade has not snapped off so I suspect that the spine of the knife had a different heat treat than the rest of the blade. Reading the Furi website, the knife is one piece and I suspect a lot of hammering in the hot condition to attain this form. In any event, the knife is no good and even being an Engineer does not confer the knowledge of a Metalurgist.

I have Wusthof cleavers and a Wusthof Chinese Chef knife. None has suffered any cracks or other defects. -Dick

Edited February 23, 2010 by budrichard (log)

[ray goud]

I do know some metallurgy from my years in making surgical instruments, and those knives are improperly made, in my opinion. They aren't performing the heat treating properly, if at all. Either keep getting the company to replace them (and hope for a better-done job in the future) or find a better brand.

Ray

[Dakki]

As far as I am aware, I have never noticed the cracking occurring during use, only in storage (taking it from the magnetic rack and then finding it cracked).

From the photo and your description of the problems, I think it's due to stress cracking, probably the result of improper heat treatment, as other people mentioned.

This isn't necessarily because of the steel-shaping process; when you heat treat steel to achieve the desired hardness, you basically heat it to the austenitic crystal phase, then cool it rapidly (quench) so some of the austenite becomes martensite, which is extremely hard and brittle. More martensite means a harder steel, which is good in this context as it'll resist deformation, giving you the possibility of using a sharper angle at the edge (and thus a sharper knife), but too much will result in an edge that chips easily. It all depends on the exact alloy used, which in turn will be a compromise between hardness, wear resistance, corrosion resistance, cost, etc etc etc.

Rapid cooling will also produce internal stress as the material cools and contracts at different rates; combining hard but brittle martensite with internal stress can easily result in catastrophic failure.

The typical solution is to heat it again (temper), enough that the steel is soft enough while hot for the stress to work itself out, so to speak, hold the temperature for a while (how hot and how long will depend on the shape and size of the piece and the exact alloy used) and then allow it to cool slowly enough that all the steel cools at approximately the same rate, so you don't re-stress the metal.

tl;dr Somebody screwed up at the oven.

I'm going to join the choir and suggest you return the knife and politely but firmly demand your money back. Catastrophic failure while you were actually using the knife would really be catastrophic.

EDIT: Not a metallurgist but I play one at work.

Edited February 23, 2010 by Dakki (log)

[helenjp]

The Furi Pro knives appear to be made in China. I expect that China can make good knives, but it's not known for steel knives.

I am not sure whether Furi is incorporated in Australia or in the US, but their promotional material stresses that their knives have at least some nontraditional aspects in design/manufacture.

[budrichard]

Not 'stress cracking' http://en.wikipedia.org/wiki/Stress_corrosion_cracking , but more likely brittle fracture (In brittle fracture, no apparent plastic deformation takes place before fracture.) from improper heat treating. But without the blade to section and analyze the fracture surface, we can't know positivly. -Dick

Edited February 24, 2010 by budrichard (log)

[Dakki]

"Stress cracking" does indeed seem to be used as a synonym for corrosion stress cracking. My apologies, English is not my first language. That said, brittle fracture is the result of crack propagation.

"Brittle fracture is characterised by the very small amount of work absorbed and by a crystalline appearance of the surfaces of fracture, often with a chevron pattern pointing to the origin of fracture, due to the formation of discontinuous cleavage cracks which join up (Fig. 4). It can occur at a low stress of 75-120 MPa with great suddenness; the velocity of crack propagation is probably not far from that of sound in the material in this type of fracture plastic deformation is very small, and the crack need not open up considerably in order to propagate, as is necessary with a ductile failure."

http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=44

And I agree we won't know for sure what the cause is unless Luke sends the blade to a lab, but improper tempering seems to me overwhelmingly probable.

[budrichard]

"EDIT: Not a metallurgist but I play one at work. "

While my degrees are in Nuclear Engineering, my Graduate studies and research are in Metalurgy.

"but improper tempering seems to me overwhelmingly probable."

Another possibility is that a defect in the lattice structure such as an inclusion caused a stress riser and led to fracture.

My original statement stands, "But without the blade to section and analyze the fracture surface, we can't know positivly."EOT-Dick

[Dakki]

What are the odds of that happening three times in a row?

[gdweatherford]

Hello Luke,

I have just cracked my first Furi Cleaver and am reluctant to replace even under warranty as I could easily have lost more than a knife. Have you any further info on defects or production shortcomings etc.?

 

Glenn

 

[dcarch]

I have made a few knives, and I have cracked a few.

 

Too aggressive hardening and/or improper tempering, IMHO, caused those spontaneous cracks. A manufacturer's fault, not a user's fault.

 

 

dcarch

[basquecook]

Do you have photos or a thread on knives you have made dcarch

[dcarch]

Do you have photos or a thread on knives you have made dcarch

 

I will take some pictures and post on another thread in a few days.

 

dcarch

[weinoo]

27 minutes ago, rrigreid said:

I wanted to get your opinion on the subject of a meat cleaver in the home kitchen. By 'meat cleaver' I mean a large, heavy cleaver that can chop bone - larger than a Chinese cleaver and much, much heavier. I purchased an old rusted meat cleaver over a year ago with the intent to restore it, but it has recently occurred to me I'm not really sure when I'd use it. Do you keep a large meat cleaver? What do you use it for? Does it have a place in home kitchens?

 

I have a meat cleaver in the kitchen. Rarely used.  Also, there are the heavier Chinese cleavers, often seen and used in the front window of Chinese-American restaurants here, where the roasted meats and poultry are hacked on a giant (what looks like) tree trunk slice.

[Dr. Teeth]

On 3/15/2022 at 10:55 AM, weinoo said:

 

I have a meat cleaver in the kitchen. Rarely used. 

What he said.    I use it for a couple things, but mostly because it’s there.  Almost everything it does could be done, albeit more slowly, with the heel of a non Japanese chef’s knife.  I love my knives, but one day when the kids move out and I squire Mrs Dr Teeth to an intimate romantic downsized local, it will find its way to a yard sale.

[kayb]

I have a big, heavy Chinese one. Problem is, I don’t have enough hand/arm strength to guide/use it and cleave it in one blow, or land repeated blows in the same place.

[weinoo]

3 hours ago, kayb said:

I have a big, heavy Chinese one. Problem is, I don’t have enough hand/arm strength to guide/use it and cleave it in one blow, or land repeated blows in the same place.

Without a doubt, that becomes harder and harder. Whereas I used to use the cleaver to hack chicken into smaller pieces, now I resort to the good old poultry shears.

[paulraphael]

I have a couple of big dumb cleavers. One is a $5 hunk of sheetmetal from Chinatown, the other a hand-me-down. I use them to cut anything that would be a bit too abusive for my biggest dumbest chef's knife. I learned my lesson when chopping through the neck bone of 20lb turkey many years ago. My German knife went straight in the mail to Dave Martell for repairs. 

 

For me the trouble with big cleavers is you need an appropriate cutting board—one you don't mind getting hacked up. That's one more big dumb thing to store, and it takes up more room than the cleaver.

[btbyrd]

I don't know that there's much of a place for heavy cleavers in the home kitchen. Or in a professional kitchen. Or even a butcher shop. (Most butchers that need to cut through bone are going to use a saw.) The one place where I think a more robust cleaver may come in handy is in finishing some Asian poultry preparations that involve cutting (hacking) cooked chicken or duck legs... but apart from those, I can't think of when I'd use one. I do know that if I *did* want to get one, I'd buy one of the heavier CCK cleavers like their bone chopper.

 

In my kitchen, the thing that's closest to a cleaver and does all of my dirty jobs is a Tojiro DP 240mm western deba. It's shaped like a French chef's knife, but it's half a centimeter thick and weighs almost a full pound. It slays. 

 

 

 

 

Edited March 26, 2022 by btbyrd (log)