Rex 45 vs K390?

[aaronkb]

I’ve seen threads about each of these, but I haven’t seen a direct comparison of the two. What are your thoughts? I have a para 3 and a pm2 in K390 and I’m wondering whether Rex 45 is different enough to be worth picking up or whether it’d be somewhat redundant.

Thanks,
Aaron

[Albatross]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Both are excellent and both sharpen easily, relative to other "super" steels. Neither will disappoint with edge retention or edge stability.

[AwayFromMySpydieHole]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Both are excellent and both sharpen easily, relative to other "super" steels. Neither will disappoint with edge retention or edge stability.

Rex45 is not going to outlast k390 at comparable hardnesses.

[koenigsegg]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Both are excellent and both sharpen easily, relative to other "super" steels. Neither will disappoint with edge retention or edge stability.

Rex45 is not going to outlast k390 at comparable hardnesses.

K390 will hold edge longest

[Doeswhateveraspidercan]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

[Mattysc42]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

Because extremely effective rust preventatives like eezox exist. So long as you don’t use your non-stainless folders for food prep, there is zero reason to care about corrosion resistance. If using folders to cut food is something you do, the salt series has you covered at reasonable prices.

[Albatross]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

If salt is avoided and the blades are kept dry, the worst you'll see is a patina. I haven't been afraid to get the blades wet or really use them, I just make sure they don't stay dirty for long and clean them after each use.

I don't sweat heavily, or live in an area with airborne salinity, so that definitely helps, but neither my Rex45 Military or K390 Police have anything more than a very mild patina. I've actually been hoping for more, but the knives generally only cut dry materials, as that's what my cutting needs entail. I don't have any food prep or otherwise potentially corrosive cutting tasks to put the knives through, so this is my chance to work on being patient.

Given the differences in sweat, location, and possibly blade maintenance, your experiences can vary quite a bit.

[The Meat man]

I'm guessing the edge strength would be similar, maybe a slight nod to REX 45 on that since they ran that around 66 to 67 HRC, and the K390 PM2 closer to 63.

On wear resistance (such as with cutting cardboard) I'd expect the K390 to win out since it has twice the carbide volume as REX 45, and harder carbide to boot.

I own both steels and can't tell a difference in corrosion resistance. Neither are stainless obviously, but I've never had any rust issues or anything, and I have used both for food prep.

[vivi]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

Because extremely effective rust preventatives like eezox exist. So long as you don’t use your non-stainless folders for food prep, there is zero reason to care about corrosion resistance. If using folders to cut food is something you do, the salt series has you covered at reasonable prices.

Can't say I agree with these thoughts at all.

Coating a blade does nothing to stop liners, hardware, lock parts etc. from rusting. And coating can be worn off.



Notice the blade is fine, despite being used to cut food many times.

[DukeNiemand]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

I have both and the Rex 45 is noticeably more rust resistant. Even used it for food prep and carried it in sweaty shorts without issue.

[Mattysc42]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

Because extremely effective rust preventatives like eezox exist. So long as you don’t use your non-stainless folders for food prep, there is zero reason to care about corrosion resistance. If using folders to cut food is something you do, the salt series has you covered at reasonable prices.

Can't say I agree with these thoughts at all.

Coating a blade does nothing to stop liners, hardware, lock parts etc. from rusting. And coating can be worn off.



Notice the blade is fine, despite being used to cut food many times.

Eezox penetrates the steel and doesn’t rub off if soaked for a few hours a single time. I soak all the metal parts of a knife for a single afternoon and I never see any rust or patina, ever, even on 1095 with years of use. I’ve put my pma11 mule and stripped becker bk5 in the dishwasher a couple dozen times and haven’t patinad either, even under the scales.

[vivi]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

Because extremely effective rust preventatives like eezox exist. So long as you don’t use your non-stainless folders for food prep, there is zero reason to care about corrosion resistance. If using folders to cut food is something you do, the salt series has you covered at reasonable prices.

Can't say I agree with these thoughts at all.

Coating a blade does nothing to stop liners, hardware, lock parts etc. from rusting. And coating can be worn off.



Notice the blade is fine, despite being used to cut food many times.

Eezox penetrates the steel and doesn’t rub off if soaked for a few hours a single time. I soak all the metal parts of a knife for a single afternoon and I never see any rust or patina, ever, even on 1095 with years of use. I’ve put my pma11 mule and stripped becker bk5 in the dishwasher a couple dozen times and haven’t patinad either, even under the scales.

https://www.bladeforums.com/threads/eez ... e.1142828/

[The Mastiff]

If REX45 is worse, really why this discussion?

Because they are excellent steels and we like them. In fact I prefer them over any stainless. Now is it OK to discuss them? :)

[jpm2]

For 15 years I carried the same non stainless blade, and like Vivi's P4 example, the only thing that ever rusted were the stainless liners. I eventually figured out how to minimize that.
Too bad the fear of rust keeps so many away from the better steels.

It's hard to compare two excellent steels like k390 and rex45, but I'll go along with the opinion that in a nutshell, rex45 is a little more resistant to edge fracture and k390 will stay sharp longer most of the time.

[Doeswhateveraspidercan]

K390 is a rust bucket had it in Police4 and will never buy it again.

If REX45 is worse, really why this discussion?

Because extremely effective rust preventatives like eezox exist. So long as you don’t use your non-stainless folders for food prep, there is zero reason to care about corrosion resistance. If using folders to cut food is something you do, the salt series has you covered at reasonable prices.

That’s neat, Thanks, say is it food safe? All I see on Amazon is that people like using it on their firearms.

[blues]

Thanks, say is it food safe? All I see on Amazon is that people like using it on their firearms.

EEZOX is not considered food safe.

Section VI — Health Hazard Data

Route of Entry: Inhalation? YES — Skin? YES — Ingestion? YES
Carcinogenicity: NTP? NO — IARC Monographs? NO — OSHA Regulated? NO
Signs and Symptons of Exposure: Drying of skin, eye irritation, headache, dizziness, nausea

[abbazaba]

DLC would be great for both these steels. Just sayin :)

[SF Native]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Normally I would agree on the toughness but the Rex is run so hard, I’m not sure it’s still tougher.
Anyone have info on this?

[Albatross]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Normally I would agree on the toughness but the Rex is run so hard, I’m not sure it’s still tougher.
Anyone have info on this?

I'll have to look for the video(s) later, but BBB did testing on both and those were his results. He found Rex45 to be more stable at the edge than M4.

[TkoK83Spy]

In the most simple terms, Rex45 is tougher and K390 will hold an edge longer.

Normally I would agree on the toughness but the Rex is run so hard, I’m not sure it’s still tougher.
Anyone have info on this?

I'll have to look for the video(s) later, but BBB did testing on both and those were his results. He found Rex45 to be more stable at the edge than M4.

I remember this. He tested them by intentionally biting into a brass bar I believe? M4 chipped or rolled, yet Rex45 suffered no damage. It was painful to watch and hear, but nice to see the strength of these steels really put to work.