Stress (MPa) 11. At what stress will the plastic deformation start for the specimen whose stress-strain curve is shown below? a) 0 MPa b) 270 MPa c) 350 MPa d) 410 MPa Justify your answer with a graphical solution. 450 400 350 300 250 200 150 100 50 0 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09