Laser engraving causing a severe loss of strength in 8670 @ 59 RC

[Hubert S.]

I don't know the exact model, but it's a 25W Keyence.

 

[Kraken Tactical Edc]

J

I don't know the exact model, but it's a 25W Keyence.

I just looked up the brand they are completely different to mine. The one you are using my also be UV laser marker which I have no experience with they say that they are auto focus where as mine is manually adjusted. Program I use to run mine is EZCAD

 

[JMJones]

Could you laser engrave it prior to heat treat, use some anti scale compound to keep it clean?

 

[killthelights]

I do a lot of laser engraving and extremely complex designs sometimes running the laser for upto a hour each side. The laser actually shouldn't leave the steel hot to touch at all provided it is set up correctly hight, speed, power and focal strength it shouldn't even create any smoke or charring on the edges of the marking. Each hatch pass needed to be tuned- higher power slower speed one pass then alternate lower power faster speeds. You can't just run it at high power as once it's vapourised first layer and it forms that black carbon layer the if left at the same setting its just going to keep generating heat and not actually remove much lmaterial from the steel as the its just creating another layer of carbon. By the time you got to the visible depth on the steel you have shown where its broken the laser has actually affected the steel probably all completely through to its thickness like a perforated line invisible to the eye. If you were to surface grind that steel to the depth of 0.003 as you mentioned was the depth of the etch it will still be visible past that even if you continue to surface grind till it was no longer visible the line would show once you dipped it in some ferric chloride. Laser etching won't affect strength if done correctly also not sure what type of laser you are using but to mark a line like the images you posted should only take a fraction of a second even at a slow speed speed of 100mm/s it will be done faster than you can blink.

I think I learned more about using my laser from this one post reply than I have from months of research on other social media/forums. Cheers! @Kracken82 Do you have examples of your laser work posted somewhere I could check it out?

 

[Kraken Tactical Edc]

I think I learned more about using my laser from this one post reply than I have from months of research on other social media/forums. Cheers! @Kracken82 Do you have examples of your laser work posted somewhere I could check it out?

I know the feeling there is next to no information on really operating them apart from how to do basic markings even then you need to be able to understand Chinese.
I can't even guess how many knives and other projects I've screwed up at the last second trying to laser something from the computer freezing halfway through a job and I have not saved the size I was scaled at to completely setting items on fire and burning holes right through.
You can check out my ig page to see they types of laser work I've done- krakentacticaledc

 

[killthelights]

I know the feeling there is next to no information on really operating them apart from how to do basic markings even then you need to be able to understand Chinese.
I can't even guess how many knives and other projects I've screwed up at the last second trying to laser something from the computer freezing halfway through a job and I have not saved the size I was scaled at to completely setting items on fire and burning holes right through.
You can check out my ig page to see they types of laser work I've done- krakentacticaledc

Awesome! Thanks!

 

[JTknives]

Pic 1: bottom knife shows laser-engraved line used for testing purposes; this knife (in a different steel) survived the hammer test. Broken knives are 8670 that were tempered at 450F and 500F. Thickness of broken knives is 0.225".

Pic 2: close-up of broken star, through text "1Ni". Text height is 0.09".

I can add anything about the laser as I have not gotten mine yet. But to me that grain looks huge. You said that’s 8670 heat treated by peters? The grain should be fine enough that you can not see it with your naked eye. If you want you can send me a chunk of that and I will do a grain refine and heat treat on it free of charge and you can retest to see what the results are.

 

[JTknives]

Here is a grain sample. This is about .02 thick and at 25-30X power on my microscope.

 

[Larrin]

You can't see fracture grain if the steel is ductile. The steel has to be brittle. Tempered steel is not good for analyzing fracture grain, especially in something tough like 8670.

 

[P.Brewster]

I can add anything about the laser as I have not gotten mine yet. But to me that grain looks huge. You said that’s 8670 heat treated by peters? The grain should be fine enough that you can not see it with your naked eye. If you want you can send me a chunk of that and I will do a grain refine and heat treat on it free of charge and you can retest to see what the results are.

Yes, 8670 purchased directly from the mill, treated by Peters.

Thanks for the offer - I am interested in having some of this steel ground/machined down to a sample size that is compatible with Larrin's charpy test. Let me know if you're equipped to do that.