Work hardening steel | Another way to progress

[bruce1337]

This concept may or may not be new to some benders but I still feel like this should be talked about because it is (probably) a lost form of training that I believe needs more attention.

To quote, "When the pressure is applied at first, a deformation forms in the metal. As the force continues and more deformation occurs, rather than weaken the metal, it strengthens it. This is due to its crystalline structure. As the crystal deformations increase, the structure becomes more complex and less slippage can occur. Along with hardening, the metal is also losing some of its ductility, so while the metal is stronger, it has a higher likelihood of fracture if enough force is applied."  [1]

We can use this property of steel to our advantage by either pre-bending bars to specific positions or by finishing off failed attempts. The main caveat being that you must let the steel harden over a period of time. Generally, the longer you wait the harder the steel can get.

For example, If I fail to finish a bar, I will wait a good month before re-attempting it. I will allow the steel to harden as much as possible so when I go to attempt it, not only am I doing isometric training but the steel has also become more difficult (sometimes up to an extra 10%). When I finally have enough strength to finish the bar with isometrics, I have become stronger overall because of the extra hardening of the steel. 

Here are two photos that visually display the hardening effect:

• The long bar is 12mm x 500mm rebar. I kinked it on my first session then moved it a little further in my second session (about a week later). Then I took a break from it for a few months then decided to come back and attempt it. I managed to finish it off, but also noticed that it bent over a new arc. This is because the original bending arc had hardened to the point that, when enough force was applied, it bent over a new arc as it was softer (following the path of least resistance)
• The 6.5" A2 bolt was bent in one session, the 7" was reversed in one session and put away for about 6 months. When I came to finish it off DO for some crush training I was amazed at how hard it was to crush down. The 7" bolt had bent over a larger arc making the final crush harder than the 6.5"

 

Edited December 9, 2021 by bruce1337

[Ole' Puller]

15 hours ago, bruce1337 said:

This concept may or may not be new to some benders but I still feel like this should be talked about because it is (probably) a lost form of training that I believe needs more attention.

To quote, "When the pressure is applied at first, a deformation forms in the metal. As the force continues and more deformation occurs, rather than weaken the metal, it strengthens it. This is due to its crystalline structure. As the crystal deformations increase, the structure becomes more complex and less slippage can occur. Along with hardening, the metal is also losing some of its ductility, so while the metal is stronger, it has a higher likelihood of fracture if enough force is applied."  [1]

We can use this property of steel to our advantage by either pre-bending bars to specific positions or by finishing off failed attempts. The main caveat being that you must let the steel harden over a period of time. Generally, the longer you wait the harder the steel can get.

For example, If I fail to finish a bar, I will wait a good month before re-attempting it. I will allow the steel to harden as much as possible so when I go to attempt it, not only am I doing isometric training but the steel has also become more difficult (sometimes up to an extra 10%). When I finally have enough strength to finish the bar with isometrics, I have become stronger overall because of the extra hardening of the steel. 

Here are two photos that visually display the hardening effect:

• The long bar is 12mm x 500mm rebar. I kinked it on my first session then moved it a little further in my second session (about a week later). Then I took a break from it for a few months then decided to come back and attempt it. I managed to finish it off, but also noticed that it bent over a new arc. This is because the original bending arc had hardened to the point that, when enough force was applied, it bent over a new arc as it was softer (following the path of least resistance)
• The 6.5" A2 bolt was bent in one session, the 7" was reversed in one session and put away for about 6 months. When I came to finish it off DO for some crush training I was amazed at how hard it was to crush down. The 7" bolt had bent over a larger arc making the final crush harder than the 6.5"

 

Spectacular post brother! I too as of late and moving forward have been pre-bending bars as well by physically bending them to kink, sweep, and crush positions then finishing them off in cycles. I find that training with work hardened stock adds considerably to the level of force needed to get the steel moving again thus increasing bending strength over a period of time. Like you mentioned, the degree in which it hardens depends on the types of steel bent and how long it sits between bends which becomes very obvious once the attempt to "finish what you've started" is made. Within this methodology of training lies a very valuable way of getting past sticking points as well as gaining strength for bigger bends down the road.

Metaphorically speaking, the desire to "get even" with a bar that once defeated you is without question exhilarating, however there's more to this than getting even. If used correctly, bending pre bent stock can serve to train the CNS along with toughening the bones, ligaments, tendons and strengthening the muscles for long term bending success. Thanks brother for this very insightful and interesting post!

 

[Blacksmith513]

Thats very interesting. Despite the name, i'm only a hobby blacksmith and I do have some knowledge in metallurgy, but only the surface. It makes sense too. Like when you bend a 60d spike... You keep bending it back and forth, it gets harder until its too hard and it snaps. 

[bruce1337]

1 minute ago, Blacksmith513 said:

Thats very interesting. Despite the name, i'm only a hobby blacksmith and I do have some knowledge in metallurgy, but only the surface. It makes sense too. Like when you bend a 60d spike... You keep bending it back and forth, it gets harder until its too hard and it snaps. 

Interesting that you point this out. Many believe the steel weakens and is why it snaps, but actually its the opposite. Like you said, bending steel back and forth actually hardens it to the point where it loses its ductility and can no lomger sustain deformation.

[bruce1337]

On 12/10/2021 at 1:55 AM, Ole' Puller said:

Spectacular post brother! I too as of late and moving forward have been pre-bending bars as well by physically bending them to kink, sweep, and crush positions then finishing them off in cycles. I find that training with work hardened stock adds considerably to the level of force needed to get the steel moving again thus increasing bending strength over a period of time. Like you mentioned, the degree in which it hardens depends on the types of steel bent and how long it sits between bends which becomes very obvious once the attempt to "finish what you've started" is made. Within this methodology of training lies a very valuable way of getting past sticking points as well as gaining strength for bigger bends down the road.

Metaphorically speaking, the desire to "get even" with a bar that once defeated you is without question exhilarating, however there's more to this than getting even. If used correctly, bending pre bent stock can serve to train the CNS along with toughening the bones, ligaments, tendons and strengthening the muscles for long term bending success. Thanks brother for this very insightful and interesting post!

 

Very well put brother! The desire to get even is one that give me the most satisfaction from bending.

I am going to experiment with a style I want to call "re-bending". Its where I take a bar I have finished and open it up as far as possible braced and let work harden, then re attempt to finish it off. then repeat the cycle until the steel eventually snaps. The idea is to maximise the amount of isometric attempts you can get with the steel. I will start with using a high grade stainless as it will take forever to snap 

[Ole' Puller]

1 hour ago, bruce1337 said:

Very well put brother! The desire to get even is one that give me the most satisfaction from bending.

I am going to experiment with a style I want to call "re-bending". Its where I take a bar I have finished and open it up as far as possible braced and let work harden, then re attempt to finish it off. then repeat the cycle until the steel eventually snaps. The idea is to maximise the amount of isometric attempts you can get with the steel. I will start with using a high grade stainless as it will take forever to snap 

That sounds great brother! High quality 1018 CRS would be great and O-1 drill rod at the diameter you're looking to train with would be agonizingly great as well .. really good idea!