Niolox+/niolox 2/lo-r4197

[Nico Cappelli]

Hy guys

Today I finished grinding a rigid boning knife, in niolox+, new version of niolox, which should have a moderate tenacity and good edge hold. Tomorrow I would have liked to harden it but, having read the datasheet, I was a little perplexed. In the very short steel description it refers to "edge holding", which makes me think that the recommended heat treatment is for knives or cutting blades, and not for bearings / molds or other heat treatments that we are not interested in ... So I wonder, why they recommend a tempering temperature between 720 - 790 ° F ?? somewhat strange temperature range in a stainless steel, as it should reduce corrosion resistance. However I would like to obtain, a final hardness of 58/60 hrc if POSSIBLE. what HT do you recommend?I can sub-zero treat if is necessary.
https://www.lohmann-stahl.de/fileadmin/redaktion/downloads/1.4197.pdf
Tanks

 

[Nico Cappelli]

In the meantime, I continued to read and found a thread, always on bladeforum, where it is pointed out that niolox + and BECUT are very similar in chemical composition. good to know, but it is still not clear to me whether it is better to exploit the secondary hardness during tempering or not. I got an idea by reading also on steel nerd.com, 2% more chromium in composition in becut (or niolox +) than niolox is used to keep the percentage of free chromium high, despite the tempering at high temperatures.could be?

 

[Stacy E. Apelt - Bladesmith]

You can drive yourself crazy reading the pros and cons of a certain steel on the tech charts.
Pick a steel for the overall best attributes and use the HT parameters stated by the manufacturer for best results if you have any doubts.

On your choice here, for greater toughness (mostly in tools) the secondary hardness is used, but I would use the primary hardening point ( lower temperature for a knife) and temper between 300 and 350F to get a hardness of Rc59. This should give good edge retention.

 

[Larrin]

Bestar is a service center not a steel producer. My guess is that Becut and Niolox+ are identical, both made by Lohmann.

if you want to see what hardness is possible, you want to austenitize the steel in 25F increments, such as 1925-2000F, quench, cryo, and temper at 300F. Find the peak hardness and either use that or 25F lower for austenitize. You can then try increments of 25F on the temper (just repeat on the same specimen and check hardness) to dial in your 58-60 Rc.

 

[Nico Cappelli]

Thanks a lot to both of you for the valuable advice. I understood that it is better to do a low temperature tempering ...

austenitize the steel in 25F increments, such as 1925-2000F.

if I want to test the samples as you said, what socking time at austenitizing temperature should I use?

 

[Larrin]

Thanks a lot to both of you for the valuable advice. I understood that it is better to do a low temperature tempering ...

if I want to test the samples as you said, what socking time at austenitizing temperature should I use?

Try 20 minutes.