Community Sharpening Journal, Part 2

[Jeb]

Now I am no expert of stropping or anything close, but it sounds to me you may be leaning on the apex of the angle to hard when your stropping.

Try your next run at this by a lighter touch to start with, but also lay the blade more flat on the strop. After all you got this edge sharp already, all we are doing here is just the finish touch and bringing out that razor finish. This make any sense?

I am not so good at typing things and getting what I would show and tell a person lol...

[Scandi Grind]

I think I understand what your saying just fine. I doubt that pressure has been my problem so far. My touch is typically extremely light at this stage. It could be an angle control problem, which I do not rule out yet, but I think a lot of it has to do with the fact that I really like edges with more bite/toothiness, and stropping will always remove a bit of that toothiness, so I tend to shy away from trying it more.

[LazyOutdoorsman]

In my experience, doing super feather light passes gives me undesirable results.
I haven't done it in a few months, but last time I used super light passes on 1um from 600grit diamond. Doing so either didn't do anything meaningful, or decreased the aggressiveness of the edge.
Now, I still use the same system, but I add a little bit more pressure than the weight of the knife. Doing this makes my knives have a refined bite.

[Scandi Grind]

Well now, that's interesting. Maybe my problem has been too light of a touch. I guess that gives me something I haven't tried yet.

[Mage7]

I have had an edge that scrape shaved arm hair on both sides that I then stropped and afterward found it harder to shave hair with though.

Well, if you take an edge that's only scrape shaving, then either it has a burr, or the apex radius is just too wide to shave well. Todd Simpson showed the threshold for an apex that will shave to be about 100 nano meters (.01 micron) and that even 50 nm more will make it too wide to shave. So then suppose you had an apex that was 200-300 nm, stropping it just isn't going to take it down to 100 nm and will only add a micro convexity that terminates in an apex that's too wide to shave but also smoothed out to the point it has no bite in slicing cuts.

The difference is that when you have an edge on a hone that's 100 nm or less at the apex and shaves easily, there is always still a burr even if it's imperceptible. In that scenario, when you strop, you're basically removing that burr by microbeveling, but that micro-convex bevel is still going to terminate into a point less than 100 nm that can shave. When you try the same on an edge that has an apex that's greater than 100 nm AND still has a burr, then removing the burr will not make the apex terminate to a point narrower than 100 nm unless it was already very close to it to begin with, but will merely make the edge feel smoother because it got rid of the burr.

Personally I don't bother to strop most of the time at all, but if I do it's not until I have an edge that's already easily shaving hair off the hone. At that point I generally only strop if one side of the edge shaves more easily than the other, which is a good indicator that you have a foil burr sticking out to one side.

[Scandi Grind]

Good break down Mage, thanks. I guess that means I don't want to change my typical method then. Ideally I would have edges smoothly shaving off of stones, but that hasn't happened yet using any technique with my hands, so I suppose I just go about things my typical way and hope to reach that next level of sharpness one day.

[Mage7]

Got a Roadie XL and this M398 is weirdly hard to sharpen. Such a little blade, and more chromium carbide than vanadium carbide, but it still took almost 3 hours to reprofile even on an Atoma 140. I think it was due to the grind from the factory being so obtuse.

This was a pretty bad job from the factory compared to Spyderco's usual quality. I've only ever had models from them produced in Golden or Taichung, but this one is from Manago, Italy... Tsk tsk, Manago factory:

I'm not sure if the 3 degree difference per side is more egregious, or if the 50 degree inclusive edge angle is. I'm also surprised that primary blade grind is this obtuse, as most Spydercos I have seen are around 2.5 degrees.

Well, so I grabbed a 10 degree angle wedge to try to get a 15 dps edge instead, and I ended up pretty close. Got the 30 inclusive I wanted, but more like 14 on one side and 16 on the other...

I tried to start out with the 400 grit Atoma, but jeez this stuff was an absolute bear to grind. This was really shocking to me because I have ground a couple 15V knives, the HIC Mule, K294, ZDP-189, etc. and none have been as hard to grind as this. I wonder if maybe my 260 micron SiC stone would have been faster, but I didn't really want to risk excessive micro chipping since M398 is supposed to be pretty brittle. I'm mostly happy with the results, but I am not really happy with the flat I ended up grinding into the tip. I'm not usually one that makes a big deal out of uneven bevel width, but that bothers me. There were a couple micro chips visible with a pocket microscope, undoubtedly from using the 140, but given the obtuse grind on the blade I just decided to leave them so I wasn't increasing the thickness behind the edge unnecessarily.

You can definitely tell I kicked the handle up a bit much... That should be one smooth radius, not a flat on a radius.

But I'm happy with it overall. Finished on the Atoma 1200

I don't have any of those baby hairs, but it whittles wiry beard hair just fine

[ejames13]

PXL_20260206_122524750~2.jpg

Got a Roadie XL and this M398 is weirdly hard to sharpen. Such a little blade, and more chromium carbide than vanadium carbide, but it still took almost 3 hours to reprofile even on an Atoma 140. I think it was due to the grind from the factory being so obtuse.

This was a pretty bad job from the factory compared to Spyderco's usual quality. I've only ever had models from them produced in Golden or Taichung, but this one is from Manago, Italy... Tsk tsk, Manago factory:

PXL_20260206_085717940~2.jpg

I'm not sure if the 3 degree difference per side is more egregious, or if the 50 degree inclusive edge angle is. I'm also surprised that primary blade grind is this obtuse, as most Spydercos I have seen are around 2.5 degrees.

Well, so I grabbed a 10 degree angle wedge to try to get a 15 dps edge instead, and I ended up pretty close. Got the 30 inclusive I wanted, but more like 14 on one side and 16 on the other...

PXL_20260206_123648920~2.jpg

I tried to start out with the 400 grit Atoma, but jeez this stuff was an absolute bear to grind. This was really shocking to me because I have ground a couple 15V knives, the HIC Mule, K294, ZDP-189, etc. and none have been as hard to grind as this. I wonder if maybe my 260 micron SiC stone would have been faster, but I didn't really want to risk excessive micro chipping since M398 is supposed to be pretty brittle. I'm mostly happy with the results, but I am not really happy with the flat I ended up grinding into the tip. I'm not usually one that makes a big deal out of uneven bevel width, but that bothers me. There were a couple micro chips visible with a pocket microscope, undoubtedly from using the 140, but given the obtuse grind on the blade I just decided to leave them so I wasn't increasing the thickness behind the edge unnecessarily.

You can definitely tell I kicked the handle up a bit much... That should be one smooth radius, not a flat on a radius.

PXL_20260206_121521721.MP~2.jpg
PXL_20260206_122551064~2.jpg
PXL_20260206_122705919~2.jpg

But I'm happy with it overall. Finished on the Atoma 1200

PXL_20260206_122517091~2.jpg
PXL_20260206_122645511~2.jpg

I don't have any of those baby hairs, but it whittles wiry beard hair just fine

PXL_20260206_132552068~3.jpg

I often end up doing that to the tip during extended reprofile sessions. Grow impatient. Try to move faster. Make mistakes usually at the tip or heel. Very frustrating.

I've started limiting myself to 15-20 minutes per session to avoid that. 3 hours straight with a 140 grit plate is insane. Would've taken me a week or more.

[TkoK83Spy]

Nice work, looks good! Appreciate the details.

[Scandi Grind]

I'm not familiar with M398 or what realm it resides in. Is there another steel that is considered similar too?

[Mage7]

I'm not familiar with M398 or what realm it resides in. Is there another steel that is considered similar too?

I would say it's most comparable to S110V and S125V It has nearly a carbide volume of about 30%. While S125V is split about 50/50 with chromium carbides and vanadium carbides, M398 is 25% chromium carbide and 5% vanadium carbide. Which, while that's still an extremely high carbide content, chromium carbides are on the softer end of the scale of hardness. I would also say it's similar to ZDP-189 since that is at 30% carbide volume too, but with ALL chromium carbides.

(From Knife Steel Nerds)


I've ground S90V, ZDP-189, and M390 (as well as others I mentioned above) without as much difficulty.

The grain structure is remarkably similar to S110V:

M398:


S110V


It's also up there in that range for CATRA score:


There's a whole article on it if you want to know more

https://knifesteelnerds.com/2020/10/26/ ... -and-more/

His remarks about the sharpening and grindability sort of miss the mark with my experience in relation to S90V but are similar otherwise.

Ease in Sharpening and Grinding

The most common abrasive type in sharpening stones, sandpaper, and grinding belts is aluminum oxide, which is softer than vanadium carbide. Therefore, the higher the vanadium carbide fraction the more difficult sharpening can be when it comes to material removal. So M398 may be somewhat easier to sharpen than S90V, S110V, or S125V but more difficult than M390, S60V, and ZDP-189. When using CBN or diamond sharpening stones this difference is removed and how difficult it is to grind away material is then roughly proportional to the edge retention of each steel (higher edge retention means harder to sharpen). However, removing material is only one element of sharpenability. Deburring, for example, is primarily controlled by hardness and the amount of retained austenite, which is more controlled by heat treatment than steel. The CATRA knife austenitized at 2050°F along with cryo was relatively easy to deburr. Using higher austenitizing temperatures or skipping cryo could make deburring more difficult by increasing the amount of retained austenite.

It's just what I find weird is that while vanadium is supposed to be the hardest carbide former and make steels harder to grind, it was much more difficult to grind than 15V or K294(10V) Though I suppose just overall carbide volume might matter more, and both of those have a good bit less carbide volume. I think K294 (10V} is at about 18% and 15V is about 23%, both with just pure vanadium carbides. But those were much easier to grind, and in much bigger blades too.

[LazyOutdoorsman]

I'm not familiar with M398 or what realm it resides in. Is there another steel that is considered similar too?

I would say it's most comparable to S110V and S125V It has nearly a carbide volume of about 30%. While S125V is split about 50/50 with chromium carbides and vanadium carbides, M398 is 25% chromium carbide and 5% vanadium carbide. Which, while that's still an extremely high carbide content, chromium carbides are on the softer end of the scale of hardness. I would also say it's similar to ZDP-189 since that is at 30% carbide volume too, but with ALL chromium carbides.

(From Knife Steel Nerds)


I've ground S90V, ZDP-189, and M390 (as well as others I mentioned above) without as much difficulty.

The grain structure is remarkably similar to S110V:

M398:


S110V


It's also up there in that range for CATRA score:


There's a whole article on it if you want to know more

https://knifesteelnerds.com/2020/10/26/ ... -and-more/

His remarks about the sharpening and grindability sort of miss the mark with my experience in relation to S90V but are similar otherwise.

Ease in Sharpening and Grinding

The most common abrasive type in sharpening stones, sandpaper, and grinding belts is aluminum oxide, which is softer than vanadium carbide. Therefore, the higher the vanadium carbide fraction the more difficult sharpening can be when it comes to material removal. So M398 may be somewhat easier to sharpen than S90V, S110V, or S125V but more difficult than M390, S60V, and ZDP-189. When using CBN or diamond sharpening stones this difference is removed and how difficult it is to grind away material is then roughly proportional to the edge retention of each steel (higher edge retention means harder to sharpen). However, removing material is only one element of sharpenability. Deburring, for example, is primarily controlled by hardness and the amount of retained austenite, which is more controlled by heat treatment than steel. The CATRA knife austenitized at 2050°F along with cryo was relatively easy to deburr. Using higher austenitizing temperatures or skipping cryo could make deburring more difficult by increasing the amount of retained austenite.

It's just what I find weird is that while vanadium is supposed to be the hardest carbide former and make steels harder to grind, it was much more difficult to grind than 15V or K294(10V) Though I suppose just overall carbide volume might matter more, and both of those have a good bit less carbide volume. I think K294 (10V} is at about 18% and 15V is about 23%, both with just pure vanadium carbides. But those were much easier to grind, and in much bigger blades too.

It appears that grindability is a little bit different to sharpening due to the carbides. This is because on page 98 in the first edition of the Knife Engineering book, Dr. Thomas essentially said that small carbides can be effectively "scooped" out when grinding. However, large carbides may not always experience this behavior and instead smooth over or shatter, increasing the wear on the abrasives.

This could be analogized as serving very soft and over-ripe fruit salad. The spoon acts as the abrasive grit, and the very small blue berries and large strawberries act as the small and large carbides respectively. So, when scooping up some salad, you are likely to get the small blue berries relatively easily onto the spoon. However, you will catch, gouge, dent, or puncture the strawberries. This extra effort from the strawberries can tie back to grinding as large carbides add extra resistance and energy needed to get the job done.

[VandymanG]

Could use some advice. I’m looking at getting into vitrified sharpening stones. So I guess what I’m asking is what brand would you all recommend. Being that I’m just wanting to try them out and see how I do with them I don’t want to get super pricey ones. Just a good solid beginner one.

[Mage7]

I'm not familiar with M398 or what realm it resides in. Is there another steel that is considered similar too?

I would say it's most comparable to S110V and S125V It has nearly a carbide volume of about 30%. While S125V is split about 50/50 with chromium carbides and vanadium carbides, M398 is 25% chromium carbide and 5% vanadium carbide. Which, while that's still an extremely high carbide content, chromium carbides are on the softer end of the scale of hardness. I would also say it's similar to ZDP-189 since that is at 30% carbide volume too, but with ALL chromium carbides.

(From Knife Steel Nerds)


I've ground S90V, ZDP-189, and M390 (as well as others I mentioned above) without as much difficulty.

The grain structure is remarkably similar to S110V:

M398:


S110V


It's also up there in that range for CATRA score:


There's a whole article on it if you want to know more

https://knifesteelnerds.com/2020/10/26/ ... -and-more/

His remarks about the sharpening and grindability sort of miss the mark with my experience in relation to S90V but are similar otherwise.

Ease in Sharpening and Grinding

The most common abrasive type in sharpening stones, sandpaper, and grinding belts is aluminum oxide, which is softer than vanadium carbide. Therefore, the higher the vanadium carbide fraction the more difficult sharpening can be when it comes to material removal. So M398 may be somewhat easier to sharpen than S90V, S110V, or S125V but more difficult than M390, S60V, and ZDP-189. When using CBN or diamond sharpening stones this difference is removed and how difficult it is to grind away material is then roughly proportional to the edge retention of each steel (higher edge retention means harder to sharpen). However, removing material is only one element of sharpenability. Deburring, for example, is primarily controlled by hardness and the amount of retained austenite, which is more controlled by heat treatment than steel. The CATRA knife austenitized at 2050°F along with cryo was relatively easy to deburr. Using higher austenitizing temperatures or skipping cryo could make deburring more difficult by increasing the amount of retained austenite.

It's just what I find weird is that while vanadium is supposed to be the hardest carbide former and make steels harder to grind, it was much more difficult to grind than 15V or K294(10V) Though I suppose just overall carbide volume might matter more, and both of those have a good bit less carbide volume. I think K294 (10V} is at about 18% and 15V is about 23%, both with just pure vanadium carbides. But those were much easier to grind, and in much bigger blades too.

It appears that grindability is a little bit different to sharpening due to the carbides. This is because on page 98 in the first edition of the Knife Engineering book, Dr. Thomas essentially said that small carbides can be effectively "scooped" out when grinding. However, large carbides may not always experience this behavior and instead smooth over or shatter, increasing the wear on the abrasives.

This could be analogized as serving very soft and over-ripe fruit salad. The spoon acts as the abrasive grit, and the very small blue berries and large strawberries act as the small and large carbides respectively. So, when scooping up some salad, you are likely to get the small blue berries relatively easily onto the spoon. However, you will catch, gouge, dent, or puncture the strawberries. This extra effort from the strawberries can tie back to grinding as large carbides add extra resistance and energy needed to get the job done.

I was wondering if the size of the carbides might have been the big difference here, although ZDP-189 carbides are also pretty large and never had the same experience. Bur I believe the chromium carbides in M398 were "vanadium enriched" which are evidently a lot harder than basic chromium carbides.

In any case, I was seeing a good amount of micro-chipping at 15 dps so I decided to aim for 20--got 19 but close enough. Rather than reset the entire bevel I just added a small additional bevel. I wouldn't call this a "micro" bevel though.

Already tested it a bit on what had caused the micro chipping--slicing through the blister packs some cold medicine comes in--and so far, so good.

[Scandi Grind]

Looks good from here. I imagine it should be plenty durable with that adjustment. Curious what the edge retention will be like for that steel.

[Mage7]

Looks good from here. I imagine it should be plenty durable with that adjustment. Curious what the edge retention will be like for that steel.

It's still micro chipping a tiny bit, but not nearly as bad as at 15 dps. That could just be the mode of failure for this steel. I have heard that's the case for S110V and the grain structures are very similar.

CATRA edge retention is extremely high, but generally speaking I don't ever really let my knives dull to the extent that CATRA tests samples are dulled to within the first stroke of the test, so it's hard to say. It kept a hair whittling edge for a couple of days cutting through foil and plastic blister packs, and skinning a few apples, which doesn't sound like much but I haven't had any steels hold a hair whittling edge for any longer than that. I'll see how long it keeps a shaving edge afterwards but I have a feeling it won't be substantially different than S90V. Usually hardness has more to do with that than carbide content, in my experience, and I don't think they run this M398 much over 60-62 HRC.

[tomhosangoutdoors]

I'm not familiar with M398 or what realm it resides in. Is there another steel that is considered similar too?

I would say it's most comparable to S110V and S125V It has nearly a carbide volume of about 30%. While S125V is split about 50/50 with chromium carbides and vanadium carbides, M398 is 25% chromium carbide and 5% vanadium carbide. Which, while that's still an extremely high carbide content, chromium carbides are on the softer end of the scale of hardness. I would also say it's similar to ZDP-189 since that is at 30% carbide volume too, but with ALL chromium carbides.

(From Knife Steel Nerds)


I've ground S90V, ZDP-189, and M390 (as well as others I mentioned above) without as much difficulty.

The grain structure is remarkably similar to S110V:

M398:


S110V


It's also up there in that range for CATRA score:


There's a whole article on it if you want to know more

https://knifesteelnerds.com/2020/10/26/ ... -and-more/

His remarks about the sharpening and grindability sort of miss the mark with my experience in relation to S90V but are similar otherwise.

Ease in Sharpening and Grinding

The most common abrasive type in sharpening stones, sandpaper, and grinding belts is aluminum oxide, which is softer than vanadium carbide. Therefore, the higher the vanadium carbide fraction the more difficult sharpening can be when it comes to material removal. So M398 may be somewhat easier to sharpen than S90V, S110V, or S125V but more difficult than M390, S60V, and ZDP-189. When using CBN or diamond sharpening stones this difference is removed and how difficult it is to grind away material is then roughly proportional to the edge retention of each steel (higher edge retention means harder to sharpen). However, removing material is only one element of sharpenability. Deburring, for example, is primarily controlled by hardness and the amount of retained austenite, which is more controlled by heat treatment than steel. The CATRA knife austenitized at 2050°F along with cryo was relatively easy to deburr. Using higher austenitizing temperatures or skipping cryo could make deburring more difficult by increasing the amount of retained austenite.

It's just what I find weird is that while vanadium is supposed to be the hardest carbide former and make steels harder to grind, it was much more difficult to grind than 15V or K294(10V) Though I suppose just overall carbide volume might matter more, and both of those have a good bit less carbide volume. I think K294 (10V} is at about 18% and 15V is about 23%, both with just pure vanadium carbides. But those were much easier to grind, and in much bigger blades too.

It appears that grindability is a little bit different to sharpening due to the carbides. This is because on page 98 in the first edition of the Knife Engineering book, Dr. Thomas essentially said that small carbides can be effectively "scooped" out when grinding. However, large carbides may not always experience this behavior and instead smooth over or shatter, increasing the wear on the abrasives.

This could be analogized as serving very soft and over-ripe fruit salad. The spoon acts as the abrasive grit, and the very small blue berries and large strawberries act as the small and large carbides respectively. So, when scooping up some salad, you are likely to get the small blue berries relatively easily onto the spoon. However, you will catch, gouge, dent, or puncture the strawberries. This extra effort from the strawberries can tie back to grinding as large carbides add extra resistance and energy needed to get the job done.

I was wondering if the size of the carbides might have been the big difference here, although ZDP-189 carbides are also pretty large and never had the same experience. Bur I believe the chromium carbides in M398 were "vanadium enriched" which are evidently a lot harder than basic chromium carbides.

In any case, I was seeing a good amount of micro-chipping at 15 dps so I decided to aim for 20--got 19 but close enough. Rather than reset the entire bevel I just added a small additional bevel. I wouldn't call this a "micro" bevel though.

Already tested it a bit on what had caused the micro chipping--slicing through the blister packs some cold medicine comes in--and so far, so good.

PXL_20260208_040546893~2.jpg

PXL_20260208_041059768~3.jpg

I think you're a bit more acute on your edge angles than you believe, which would explain why they're larger. The brightest spots on the outermost sides of the beam on your goniometer are the secondary bevel angles. The brightest towards the middle is the angle of the primary grind. So it's looking more like you're at 12 and 13 DPS which may explain some of the micro chipping.

[Mage7]

I would say it's most comparable to S110V and S125V It has nearly a carbide volume of about 30%. While S125V is split about 50/50 with chromium carbides and vanadium carbides, M398 is 25% chromium carbide and 5% vanadium carbide. Which, while that's still an extremely high carbide content, chromium carbides are on the softer end of the scale of hardness. I would also say it's similar to ZDP-189 since that is at 30% carbide volume too, but with ALL chromium carbides.

(From Knife Steel Nerds)


I've ground S90V, ZDP-189, and M390 (as well as others I mentioned above) without as much difficulty.

The grain structure is remarkably similar to S110V:

M398:


S110V


It's also up there in that range for CATRA score:


There's a whole article on it if you want to know more

https://knifesteelnerds.com/2020/10/26/ ... -and-more/

His remarks about the sharpening and grindability sort of miss the mark with my experience in relation to S90V but are similar otherwise.



It's just what I find weird is that while vanadium is supposed to be the hardest carbide former and make steels harder to grind, it was much more difficult to grind than 15V or K294(10V) Though I suppose just overall carbide volume might matter more, and both of those have a good bit less carbide volume. I think K294 (10V} is at about 18% and 15V is about 23%, both with just pure vanadium carbides. But those were much easier to grind, and in much bigger blades too.

It appears that grindability is a little bit different to sharpening due to the carbides. This is because on page 98 in the first edition of the Knife Engineering book, Dr. Thomas essentially said that small carbides can be effectively "scooped" out when grinding. However, large carbides may not always experience this behavior and instead smooth over or shatter, increasing the wear on the abrasives.

This could be analogized as serving very soft and over-ripe fruit salad. The spoon acts as the abrasive grit, and the very small blue berries and large strawberries act as the small and large carbides respectively. So, when scooping up some salad, you are likely to get the small blue berries relatively easily onto the spoon. However, you will catch, gouge, dent, or puncture the strawberries. This extra effort from the strawberries can tie back to grinding as large carbides add extra resistance and energy needed to get the job done.

I was wondering if the size of the carbides might have been the big difference here, although ZDP-189 carbides are also pretty large and never had the same experience. Bur I believe the chromium carbides in M398 were "vanadium enriched" which are evidently a lot harder than basic chromium carbides.

In any case, I was seeing a good amount of micro-chipping at 15 dps so I decided to aim for 20--got 19 but close enough. Rather than reset the entire bevel I just added a small additional bevel. I wouldn't call this a "micro" bevel though.

Already tested it a bit on what had caused the micro chipping--slicing through the blister packs some cold medicine comes in--and so far, so good.

PXL_20260208_040546893~2.jpg

PXL_20260208_041059768~3.jpg

I think you're a bit more acute on your edge angles than you believe, which would explain why they're larger. The brightest spots on the outermost sides of the beam on your goniometer are the secondary bevel angles. The brightest towards the middle is the angle of the primary grind. So it's looking more like you're at 12 and 13 DPS which may explain some of the micro chipping.

Nah, if you look closely there's two edge bevels on the primary blade grind. So it goes

Primary: 4.5 Degrees
Secondary: 13 Degrees / 14 Degrees
Edge Bevel: 19 Degrees

You can kinda make out the new edge bevel in the picture but it's kinda faint. The goniometer can be hard to read, but I'm quite sure of this especially since the secondary bevel was ground using a 10 degree angle wedge, and then when that had too much microchipping, I ground in a new smaller edge bevel with a 15 degree wedge. Given that the primary blade grind is 4-5 degrees that checks out.

I wouldn't call the new edge bevel a micro-bevel personally, as I tend to put micro-bevels on a lot smaller than this one. It may still be a bit too small to give it much more structural integrity, but I don't think so because the microchipping I was seeing on the previous bevel was deeper than the new bevel is high and the microchipping on this one is barely even visible under 120x and probably not even 1/10th of the new bevel height which itself is only somewhere around .005" -.010" so when I say "micro" chipping I really mean it.

If anything I think this stuff is just so brittle and coarse grain that might need >20 DPS to avoid chipping or any kind, and it might just be this steels natural mode of wear instead of plastic deformation.