Where does the tensile strength locate?

[aiklone1314]

Hi,
i read my online note, it state that yield strength is stress at which noticeable plastic deformation has occurred but why when i see the graph, it doesn't means like what it written.
below is the graph make me confusing.

 

[heylouis]

Hi,
i read my online note, it state that yield strength is stress at which noticeable plastic deformation has occurred but why when i see the graph, it doesn't means like what it written.
below is the graph make me confusing.

Except mild steel the yield point is difficult to find. So people usually define that the stress at 0.2% inelastic strain is yield strength.
You can find the 0.2% inelastic strain position is drawed specially in the graph, that's the reason. And, 0.2% inelastic strain is noticeable in industry use.
It is 0.2% inelastic strain but not 0.0% because elastic deformation do not fully agrees to Hooke's law. The elastic deformation near yield stress is not linear. So 0.0% is not a proper value.