04-02-2018, 05:54 AM
Scott, thanks for all your practical guidance, highly appreciated! 
What concerns the Flextest, I agree with the cautious statement by prof. Landes: "It can be used to get an indication if a blade has its HT done in the right parameters and its geometrical figures are somewhat where you wanted them, but it is no final tool to proof quality."
The blade in the Flextest can be considered as a cantilever beam, where the deflection at the free end is proportional to the bending force and to the reciprocal value of the elastic modulus (Young’s modulus). For some reasons the effect of HT on the value of the elastic modulus is small, usually smaller then 10 to 20% of the nominal value. For this reason many technicians consider elastic modulus as a quantity which is fully independent on HT. This is simplified and not fully justified approach.
From physical point of view the elastic modulus is given by the size of inter atomic forces dominated by iron interactions. Those forces are fundamental and not changed by HT unless the lattice structure is changed. When there is a transformation to martensite than also the elastic modulus is slightly changed.
On the other hand, plastic properties of metals (e.g. hardness) are a different story, because they are heavily influenced by dislocations, which are significantly influenced by HT.
Jan
What concerns the Flextest, I agree with the cautious statement by prof. Landes: "It can be used to get an indication if a blade has its HT done in the right parameters and its geometrical figures are somewhat where you wanted them, but it is no final tool to proof quality."
The blade in the Flextest can be considered as a cantilever beam, where the deflection at the free end is proportional to the bending force and to the reciprocal value of the elastic modulus (Young’s modulus). For some reasons the effect of HT on the value of the elastic modulus is small, usually smaller then 10 to 20% of the nominal value. For this reason many technicians consider elastic modulus as a quantity which is fully independent on HT. This is simplified and not fully justified approach.
From physical point of view the elastic modulus is given by the size of inter atomic forces dominated by iron interactions. Those forces are fundamental and not changed by HT unless the lattice structure is changed. When there is a transformation to martensite than also the elastic modulus is slightly changed.
On the other hand, plastic properties of metals (e.g. hardness) are a different story, because they are heavily influenced by dislocations, which are significantly influenced by HT.
Jan