Larrin
Knifemaker / Craftsman / Service Provider
- Joined
- Jan 17, 2004
- Messages
- 4,970
In an earlier thread I posted about a method for predicting approximate toughness based on chemistry: https://www.bladeforums.com/threads/predicting-toughness-with-steel-composition.1534942/
One common question asked on Bladeforums is along the lines of, "Which Stainless steel should I use for a high toughness application?" Answers are usually along the lines of one of the powder metallurgy (PM) stainless steels commonly available such as S30V, XHP, 20CV, M390, Elmax, etc. However, all of these steels have relatively high carbide volume, leading to average at best toughness, as shown below:
https://i.imgur.com/1593U4a.png
All of these steels have carbide volume close to 10V or even higher! In other words, in answer to the question of which stainless steel is the toughest, the most common reply is the stainless equivalent of 10V. No one would say to use 10V if the question were asked about non-stainless steels. Arguments about which PM stainless steel is the toughest is the non-stainless equivalent of arguing about which is tougher between 10V and 15V. This may be a relevant question, but when one is simply looking for a "high toughness" steel, none of these PM stainless steels would seem like a good starting point. Why aren't there any lower carbide volume powder metallurgy stainless steels? That is a little more complicated, but the bottom line is they generally aren't available.
This also answers to some extent why there is a perception that stainless steels are not as tough as tool steels or carbon steels: the most commonly available and used stainless steels simply won't be that tough. Steels like AEB-L, however, have much, much lower carbide volume and can achieve much higher toughness. There seem to be very few options when it comes to steels in between, such as the 3V or Vanadis4/4V type steels but a stainless version.
Of course, these steels offer sufficient toughness for many knives and applications, which is not what I am arguing about. However, if looking for a maximum toughness steel for whatever reason, I would look outside of the PM grades.
One common question asked on Bladeforums is along the lines of, "Which Stainless steel should I use for a high toughness application?" Answers are usually along the lines of one of the powder metallurgy (PM) stainless steels commonly available such as S30V, XHP, 20CV, M390, Elmax, etc. However, all of these steels have relatively high carbide volume, leading to average at best toughness, as shown below:
https://i.imgur.com/1593U4a.png
All of these steels have carbide volume close to 10V or even higher! In other words, in answer to the question of which stainless steel is the toughest, the most common reply is the stainless equivalent of 10V. No one would say to use 10V if the question were asked about non-stainless steels. Arguments about which PM stainless steel is the toughest is the non-stainless equivalent of arguing about which is tougher between 10V and 15V. This may be a relevant question, but when one is simply looking for a "high toughness" steel, none of these PM stainless steels would seem like a good starting point. Why aren't there any lower carbide volume powder metallurgy stainless steels? That is a little more complicated, but the bottom line is they generally aren't available.
This also answers to some extent why there is a perception that stainless steels are not as tough as tool steels or carbon steels: the most commonly available and used stainless steels simply won't be that tough. Steels like AEB-L, however, have much, much lower carbide volume and can achieve much higher toughness. There seem to be very few options when it comes to steels in between, such as the 3V or Vanadis4/4V type steels but a stainless version.
Of course, these steels offer sufficient toughness for many knives and applications, which is not what I am arguing about. However, if looking for a maximum toughness steel for whatever reason, I would look outside of the PM grades.
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