Why I like M398

After tempering? Impressive!!

The charts from bohler state a maximum hardness of 64. What is your heat treatment recipe?
 
1150°C, plate quench
ice 30', 100°C 3h, 3x
magnet pass immediately after last temper
room temp 5h
65,7-67,2 HRC

With temps up to 1250°C I got max 65HRC. Interesting that higher is not better.
 
Joe...How is the edge stability at high hardness with M398?
 
navman said:
Joe...How is the edge stability at high hardness with M398?
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I didn't push it, but seems better than N690@63HRC with same geometry. Talking about thin slicers. 0.3mm before sharpening and 10dps edge. Ledeburitic can't match PM's.
With my procedure, M398 with Larrin's CATRA geometry can be hammered thru a 6mm nail. I have high faith in it for normal use. But 67 has to be tested to be sure.
 
Very carbide volume seems to help for high hardness. S90V, S110V, S125V, ZDP-189 all get to 66+ and they all have over 20% carbide volume. M398, ZDP-189, and S125V all have around 30%.
 
Larrin said:
Very carbide volume seems to help for high hardness. S90V, S110V, S125V, ZDP-189 all get to 66+ and they all have over 20% carbide volume. M398, ZDP-189, and S125V all have around 30%.
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What tempering on 100°C done to M398 steel after quenching ? Did some of retained austenite turn into martensite on 100°C tempering temperature ? Did hardness change little ? Toughness ?
 
Larrin said:
Very carbide volume seems to help for high hardness. S90V, S110V, S125V, ZDP-189 all get to 66+ and they all have over 20% carbide volume. M398, ZDP-189, and S125V all have around 30%.
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So, high hardness is possible to all of them. Nice. Didn't know that. No reason not to go high for slicers. Seems like my next is a kitchen knife. :)
 
Natlek said:
What tempering on 100°C done to M398 steel after quenching ? Did some of retained austenite turn into martensite on 100°C tempering temperature ? Did hardness change little ? Toughness ?
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It just destabilizes RA so it can cool to mart. 3x works better than 2x. After, temper to working hardness. It all depends on the intent. Just wondering if it relates to ductile to brittle transition temp, as it's in the ballpark.. Larrin Larrin ?
 
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100C tempering is too low to destabilize retained austenite. It’s also too low to increase toughness. Toughness would be decreased and hardness increased with such a low temper. Overheating the edge would also be extremely easy.
 
Larrin said:
100C tempering is too low to destabilize retained austenite. It’s also too low to increase toughness. Toughness would be decreased and hardness increased with such a low temper. Overheating the edge would also be extremely easy.
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What is the explanation of getting almost 3HRC from a 100°C temper, if not lowering RA? Seems too low for that amount of carbides.
 
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