Difference between machined QQ-N-281 Nicu Forged Bar & Hot Finished?

[Torq444]

What is the real difference between a part(i.e a large hex nut)that has been machined out of QQ-N-281 Nicu Forged Bar & one that is machined out of Hot Finished Bar?
Are the differences that significant? I know that Forging takes out all of the flaws. But with this material it seems as if forged bar is a little overkill.

 

[kumkumvijay]

As you stated the forging is going to supporting on reducing the defects due to high pressure process. In general, Also the grain flow is going to be smooth in the corners & radius but in the machining process the gains will open up and act as a notch but if the load is going to stay right angle to the grain flow direction then its has no significant different.

 

[tbuelna]

For the finish machined configuration of the part in question ("a large hex nut"), I don't think there will be much difference between using a hot forged round bar raw material and a hot rolled round bar raw material. The most common reason for specifying a forged round bar stock is to get a raw material shape that is optimized for the finish machined part size and thus minimizes waste. The raw material used for producing hot forged bar is usually hot rolled bar. As long as proper hot rolling/forging procedures for the material are used, the finished raw material products should have similar properties. The metallurgically deficient area in all hot forged or hot rolled materials is the outer surface layer, which is typically removed.

For your large hex nut, if you are making more than just a few parts you might consider using hot rolled ring forgings. The added cost of making the rolled rings will be more than offset by the savings in material cost and reduced machine time.

Good luck to you.
Terry