Forging Reduction Ratio

[qaisarabbas]

What does this ratio mean? and its relation with the mechanical properties?

We have to order few plungers for a high pressure PD pump.
Specifications required are:
Material: NT50
Shape: Forged bar (forging reduction ratio of 5:1)

[ben]

An important criterion for making forgings is the degree of hot working that goes into transforming the ingot material
into the forged product. This is measured as a Reduction Ratio obtained by dividing the original ingot cross-sectional area by the maximum cross-sectional area of the forging.
The ratio can vary from with application but a forg ing reduction ratio of 3: 1 is commonly used.
Increasing the ratio depends upon the initial / original size of ingot to be forged. While increasing the ratio decreases the ductility of the material along the transverse direction and at the same time enhancing the properties along the longitudinal axis.

[mechcolor]

I agree with Ben that the optimum forging ratio is 3 in most of the cases is 3 but in order to further enhance the mechanical / physical properties it can be kept as higher as required (proven through test coupons).
In your case of pump's plunger, the designer must have undertaken the tests to get an optimum forging reduction for Nitronic 50 so that desired mechanical properties can be achieved.

[qaisarabbas]

Thank you Ben & Mechcolor for your guidance.
Please advise which specific mechanical properties are associated with higher reduction ratio. Is it toughness, ductility or longitudinal / transverse strength?

[mechcolor]

Remember that not only the forging reduction is the only factor in determinining the final properties of the material. There are other many factors effecting the finishing properties like the forging temperature profile along the whole forging process and the material being forged.
All alone forging ratio effects the ductility of the material along the transverse direction as mentioned by Ben.
The ratio is always decided via test coupons development and testing especially in the case you are referring to.