Why we use v-notch in charpy impact test ?

[phydis]

Why we use v-notch in charpy impact test ?

 

[Chronos]

It's a ductility [or toughness] test. A simple hardness test is not representative of structural integrity as it only tests the surface. For heat treated metals, a v-notch test is more representative.

 

[Thalos]

He asked "Why"..

 

[Kevin McHugh]

The notch is the start of the failure. Stress crack propagation results from the notch being cut into the sample, and the hammer hitting the sample right at the notch.

 

[russ_watters]

Predictable, repeatable fractures happen at the consistently weakest point on the bar.

 

[Tom.G]

For a good demonstration see:

 

[Kevin McHugh]

Predictable, repeatable fractures happen at the consistently weakest point on the bar.

That too, good point Russ.