Thoughts on MagnaCut

[badmatt]

In my opinion and first hand usage.

S45vn > magnacut @ 20°

Edge retention being the most important thing to me.. Lets face it... we're not chopping down trees with our folders. I want my knife to be as sharp as possible for as long as possible and I unfortunately didn't get that with magnacut.

Give me a sebenza in S125v

 

[ferider]

Thank you for that link, Kettleman . I looked at Larrin's chart, which marginally different than the one being discussed in general, and which Larrin saw and commented on but did not correct.

It looks like MagnaCut at 64 Rc drops to the toughness of Vanax ( a great steel) and S35VN and Elmax run at typical hardnesses for knives. So the big toughness advantage of MagnaCut is lost for about a 6 percent gain in abrasive wear. That's not a tradeoff I would make. I'm curios why CRK did make that choice.

Here's Larrin's chart from the link posted by Kettleman.

It's interesting to see how close Magnacut and NitroV are. At 62.5 HRC (which is about what all the youtube knife testers call for), they are the same. NV is pretty stain-resistant, too.

 

[Twindog]

It's difficult for me to see what is exactly going on. Just in this small thread, there are three reports of chipping. Reddit has more.

When hardness goes up, strength and abrasive wear resistance go up. But at the same time, toughness goes down sharply and the edge is more vulnerable to microchipping, which decreases edge retention.

Edge stability is a blend of toughness and strength. Raising one, decreases the other. Whether there is an advantage or not depends on how the knife is used. If you're just cutting tape and string, an increase in strength at the expense of toughness will improve edge retention. If you're whittling wood or cutting plastic bands, an increase in strength at the expense of toughness will reduce edge retention.

I was looking at the Inkosi in MagnaCut, because the Inkosi is a beefed up Sebenza, with a bigger pivot and thicker blade stock. It seemed perfect for MagnaCut, because MagnaCut's big advantage over other powder stainless steels is toughness. Taking the hardness up to 64 Rc strips away that toughness advantage, all for a 6 percent increase in wear resistance. The hardness could also add an advantage in edge resistance, but only if there is no microchipping. And there are reports of microchipping, which I would not expect with MagnaCut at 61 Rc.

Snov's chart, which Larrin saw, in general, gives a different look at toughness/hardness:
visualizing-the-tradeoff-of-higher-hardness.1971444

 

[marrenmiller]

It's difficult for me to see what is exactly going on. Just in this small thread, there are three reports of chipping. Reddit has more.

When hardness goes up, strength and abrasive wear resistance go up. But at the same time, toughness goes down sharply and the edge is more vulnerable to microchipping, which decreases edge retention.

Edge stability is a blend of toughness and strength. Raising one, decreases the other. Whether there is an advantage or not depends on how the knife is used. If you're just cutting tape and string, an increase in strength at the expense of toughness will improve edge retention. If you're whittling wood or cutting plastic bands, an increase in strength at the expense of toughness will reduce edge retention.

I was looking at the Inkosi in MagnaCut, because the Inkosi is a beefed up Sebenza, with a bigger pivot and thicker blade stock. It seemed perfect for MagnaCut, because MagnaCut's big advantage over other powder stainless steels is toughness. Taking the hardness up to 64 Rc strips away that toughness advantage, all for a 6 percent increase in wear resistance. The hardness could also add an advantage in edge resistance, but only if there is no microchipping. And there are reports of microchipping, which I would not expect with MagnaCut at 61 Rc.

Snov's chart, which Larrin saw, in general, gives a different look at toughness/hardness:
visualizing-the-tradeoff-of-higher-hardness.1971444

I've had a good number of Magnacut knives at this point, with several in this same hardness range (including a Sebenza 31). The only chipping I've encountered is with factory edges. This has gone away after sharpening through the factory edge, and now those knives take very little damage even with impacts on concrete and metal. I think people are not realizing that Magnacut is tempered at fairly low temperatures to get high hardness, so it seems particularly susceptible to burnt factory edges.

It doesn't sound like anyone will be able to convince you that hardness gained can offset toughness lost, but I think you'll be pleasantly surprised if you try a CRK in Magnacut.

 

[Modernflame]

It's difficult for me to see what is exactly going on. Just in this small thread, there are three reports of chipping. Reddit has more.

When hardness goes up, strength and abrasive wear resistance go up. But at the same time, toughness goes down sharply and the edge is more vulnerable to microchipping, which decreases edge retention.

Edge stability is a blend of toughness and strength. Raising one, decreases the other. Whether there is an advantage or not depends on how the knife is used. If you're just cutting tape and string, an increase in strength at the expense of toughness will improve edge retention. If you're whittling wood or cutting plastic bands, an increase in strength at the expense of toughness will reduce edge retention.

I was looking at the Inkosi in MagnaCut, because the Inkosi is a beefed up Sebenza, with a bigger pivot and thicker blade stock. It seemed perfect for MagnaCut, because MagnaCut's big advantage over other powder stainless steels is toughness. Taking the hardness up to 64 Rc strips away that toughness advantage, all for a 6 percent increase in wear resistance. The hardness could also add an advantage in edge resistance, but only if there is no microchipping. And there are reports of microchipping, which I would not expect with MagnaCut at 61 Rc.

Snov's chart, which Larrin saw, in general, gives a different look at toughness/hardness:
visualizing-the-tradeoff-of-higher-hardness.1971444

Dude, get a Hinderer. They run the steel around 60 or 61. The blades are also twice as thick as they need to be, so it's a toughness party.

Based on the charts, I still don't get why you're saying the toughness is stripped away at 64. The chart pictured in this thread shows a modest decrease.

Any steel can chip. I've had far more chipped edges in s30v and s35vn than with magnacut.

You also might be overthinking. If you buy the knife you want, you'll probably enjoy it.

 

[Twindog]

I've had a good number of Magnacut knives at this point, with several in this same hardness range (including a Sebenza 31). The only chipping I've encountered is with factory edges. This has gone away after sharpening through the factory edge, and now those knives take very little damage even with impacts on concrete and metal. I think people are not realizing that Magnacut is tempered at fairly low temperatures to get high hardness, so it seems particularly susceptible to burnt factory edges.

It doesn't sound like anyone will be able to convince you that hardness gained can offset toughness lost, but I think you'll be pleasantly surprised if you try a CRK in Magnacut.

Thanks for that explanation.

I know that hardness can offset toughness on edge retention, but I also know it can go the other way. I can find no evidence that shows what is really lost or gained with CRK's MagnaCut at 64 Rc.

I have a Vanax blade on my Rukus that is amazing. It's not nearly as tough as MagnaCut at the same hardness, but it is the toughest of the powder stainless steels, not counting MagnaCut. It also has a slight advantage in stain resistance and edge wear. The abrasive wear resistance is lost when MagnaCut is heat treated to 64 Rc, but only by a very small amount. I don't know what happens to the stain resistance or edge retention, but the toughness advantage is completely lost.

In my hard use, Vanax has held up amazingly well. Chopping branches that has chipped S30V, deformed Aus8 and cracked A8 has caused no edge damage to Vanax, even at 15 thousandths and 15 dps.

The problem with trying an Inkosi is the expense. Pairing an expensive knife with hard-use geometry to a blade heat treated for light use seems risky.

 

[Slice-and-dice]

It's difficult for me to see what is exactly going on. Just in this small thread, there are three reports of chipping. Reddit has more.

When hardness goes up, strength and abrasive wear resistance go up. But at the same time, toughness goes down sharply and the edge is more vulnerable to microchipping, which decreases edge retention.

Edge stability is a blend of toughness and strength. Raising one, decreases the other. Whether there is an advantage or not depends on how the knife is used. If you're just cutting tape and string, an increase in strength at the expense of toughness will improve edge retention. If you're whittling wood or cutting plastic bands, an increase in strength at the expense of toughness will reduce edge retention.

I was looking at the Inkosi in MagnaCut, because the Inkosi is a beefed up Sebenza, with a bigger pivot and thicker blade stock. It seemed perfect for MagnaCut, because MagnaCut's big advantage over other powder stainless steels is toughness. Taking the hardness up to 64 Rc strips away that toughness advantage, all for a 6 percent increase in wear resistance. The hardness could also add an advantage in edge resistance, but only if there is no microchipping. And there are reports of microchipping, which I would not expect with MagnaCut at 61 Rc.

Snov's chart, which Larrin saw, in general, gives a different look at toughness/hardness:
visualizing-the-tradeoff-of-higher-hardness.1971444

T Twindog I agree completely with your analysis. My fear with buying more Magnacut is the apparent propensity to chip. Grinding out a chip in Magnacut is not easy and leaving it there doesn't feel or look right. I personally go with S30,35,45 steels- cheaper and as good/better performers in the real world IMO. Of course, I also use Buck's 420HC a lot too...

 

[marrenmiller]

Thanks for that explanation.

I know that hardness can offset toughness on edge retention, but I also know it can go the other way. I can find no evidence that shows what is really lost or gained with CRK's MagnaCut at 64 Rc.

I have a Vanax blade on my Rukus that is amazing. It's not nearly as tough as MagnaCut at the same hardness, but it is the toughest of the powder stainless steels, not counting MagnaCut. It also has a slight advantage in stain resistance and edge wear. The abrasive wear resistance is lost when MagnaCut is heat treated to 64 Rc, but only by a very small amount. I don't know what happens to the stain resistance or edge retention, but the toughness advantage is completely lost.

In my hard use, Vanax has held up amazingly well. Chopping branches that has chipped S30V, deformed Aus8 and cracked A8 has caused no edge damage to Vanax, even at 15 thousandths and 15 dps.

The problem with trying an Inkosi is the expense. Pairing an expensive knife with hard-use geometry to a blade heat treated for light use seems risky.

I'd be interested to try Vanax (got any good production recommendations?) but for me the low achievable hardness seems like a notable weak point for the steel. If I can have 64 HRC Magnacut at the same toughness as Vanax at 60 HRC, at least per Larrin's HT data, then I can't see how Vanax would hold up better in use. Maybe there's some microstructure difference between the steels, who knows...

As for the corrosion resistance, Larrin tested MC at a 2100°F austenitizing temp, which is likely what production companies shooting for 63-64 HRC are using. It had nearly the same corrosion resistance of Vanax in salt spray tests, and both steels were better than something like 20CV. I haven't been able to make MC corrode and I use it in a kitchen knife nearly every day. I don't see Vanax having much of an advantage in corrosion resistance.

 

[Kettleman]

T Twindog I agree completely with your analysis. My fear with buying more Magnacut is the apparent propensity to chip. Grinding out a chip in Magnacut is not easy and leaving it there doesn't feel or look right. I personally go with S30,35,45 steels- cheaper and as good/better performers in the real world IMO. Of course, I also use Buck's 420HC a lot too...

I’m lost on the chipping part. I have used a few magnacut inkosi HARD. I’ve also used S45VN hard before that. Only ever chipped the 45. Magnacut has proven, in my uses, to be better than the 45 for chipping and much better then the 35 for rolling.

Not a fan boy just a guy that actually uses his knives.

As for is it needed on every knife for it to be a good knife..no. I have a S30V reg in my pocket right now that I’ve been using all morning and yesterday had S35VN and tomorrow it will be BG-42.

I know some folks just don’t like new but the MC is a fantastic made to be a knife steel and all the feels won’t change that.


Oh and incase you missed it…I don’t actually own a knife in MagnaCut so I don’t have any skin in this game.

 

[Twindog]

Crucible has toughness numbers for MagnaCut that are much different than Larrin's numbers.

According to Crucible, MagnaCut has a toughness of 38 ft-lbs at 62.5 Rc and a toughness of 30 ft-lbs at 64 Rc.

By comparison, it says CPM 154 has a toughness of 26 ft-lbs at 60 Rc.

The company may be using a different method of testing toughness, but its numbers would suggest that my concerns are not warranted.

 

[marrenmiller]

Crucible has toughness numbers for MagnaCut that are much different than Larrin's numbers.

According to Crucible, MagnaCut has a toughness of 38 ft-lbs at 62.5 Rc and a toughness of 30 ft-lbs at 64 Rc.

By comparison, it says CPM 154 has a toughness of 26 ft-lbs at 60 Rc.

The company may be using a different method of testing toughness, but its numbers would suggest that my concerns are not warranted.

Yeah, you can't directly compare values between different testers, but relative differences should scale.

Thanks for sharing the Crucible figures. I wonder how closely they match with Larrin's data...

 

[ace]

Crucible has toughness numbers for MagnaCut that are much different than Larrin's numbers.

According to Crucible, MagnaCut has a toughness of 38 ft-lbs at 62.5 Rc and a toughness of 30 ft-lbs at 64 Rc.

By comparison, it says CPM 154 has a toughness of 26 ft-lbs at 60 Rc.

The company may be using a different method of testing toughness, but its numbers would suggest that my concerns are not warranted.

I agree, I think your concerns are unfounded. If Vanax works for you then so should MagnaCut since at 63-64 it is as tough or slightly tougher than your Vanax blade. MagnaCut being harder could allow you to decrease the edge angles and see significant improvements in edge holding, assuming chipping won't become an issue for your use, if it does increase the angle until it stops being a problem. Basically, if your concern is toughness, then MagnaCut should work better for you than Vanax in the ranges these steels are used. I have a lot of experience with MagnaCut in kitchen and outdoor knives and chipping is not an issue at all. I only, so far have Deka in MagnaCut, but that has lower hardness, so lack of chipping is expected. In many cases micro chipping is preferred to rolling and deforming since microchipped edges can still cut for a long time unlike bent or mushroomed edges which become fully dull. On a small folder I question the need for extreme toughness, after all before MagnaCut most high wear stainless folders had much lower toughness and yet most people don't have a problem with them. Even the much beloved, by some, 1095 has relatively low toughness, significantly lower than MagnaCut even at 63-64. Yet many swear by 1095 because it meets their needs. On the other hand 420HC is very tough and even though it is a fine steel you don't see many ask for it or for it to show extreme edge retention numbers.

 

[Modernflame]

Anecdotal evidence of chipping must be viewed in light of empirical data, since the forces involved in an individual case and the extent of the damage are hard to measure. In my case, the factory edge on a Sebenza impacted another piece of metal at more or less a right angle. The chip itself was small enough that I didn't see it immediately. I only realized it when it snagged on a later cut.

 

[Kettleman]

The problem with trying an Inkosi is the expense. Pairing an expensive knife with hard-use geometry to a blade heat treated for light use seems risky.

 

[Ironbut]

Well, I really don't need another knife, and my CRKs in S35 & 45VN have been serving me well, so I'll just stick with them.
(I probably said the same thing about my Buck 110 fifty-some years ago, and I've added "a few" since then.)