What is the most suitable hardness for a substrate material (Tool steel)?
If the substrate hardness is insufficient and the substrate shows plastic deformation, the TRD layer will probably have small cracks on the surface and will not extend the life of the die. In this case it is obvious that the die needs to be harder. What is the best hardness and does a harder die always equal longer life for the die? Is there also a minimum hardness to be insured? If the damage only exists on the surface, the substrate hardness may not be the issue. On the other hand, if the damage is penetrated into the substrate, the hardness should be the issue, and a longer life can be obtained with the higher substrate hardness if the damage is simply caused by material fatigue. Longer die life can also be obtained with a lower hardness if the damage is caused by brittleness . To best answer this question is that each circumstance is unique and does not have just one specific answer. The hardness depends on the specific die and its usage.
