Hardened Steel is NOT Stiffer Than Soft Steel

Hardening Steel Does Not Change the Stiffness Of The Steel. I does not feel intuitive, but it is true that it does not change with heat treatment. I think this is because the tensile strength changes, so getting to the point at which the steel permanently bends is harder to do, but that does not change the fact that the stiffness does not change. And I have had a few people push back on this point, so I thought that I would settle it. It is also an interesting project for me because I have never set out to actively test it. I would have liked to have done a proper tensile test, but I don't have a hydraulic press and equipment to monitor the strain. Instead we will have to resort to a bend test. That means dealing with the moment of area associated with bending, and dealing with compression and tension, but it should not be of concern because the young's modulus should effectively be the same for compression and tension. But comparing the same piece of steel unhardened and hardened will allow us to skirt any issues associated with 2nd moment of area. And spoiler, the hardness remains unaffected. #machining #heattreatment