For the alloy whose stress strum curve is shown here, state the a) tensile stren
ID: 1842670 • Letter: F
Question
For the alloy whose stress strum curve is shown here, state the a) tensile strength, b) elastic modulus, c) strain hardening coefficient (n). and d) Yield Strength at 0.2 % offset strain A tensile specimen with a 10 mm initial diameter and 60 mm gage length reaches maximum load at 100 kN and fractures at 80 kN. The maximum diameter at fracture is 8 mm. Determine (a) Engineering stress at maximum load (i.e. Ultimate Tensile Strength. UTS), (b) True Fracture Stress, (c) True Strain at fracture, and (d) engineering strain at fracture.Explanation / Answer
From Figure,
Tensile strength = 375 MPa
Elastic Modulus = 200 MPa/ 0.00025
= 80 GPa
0.2% yield strength = 250 MPa
strain hardening coefficient can be calculated by using
log(stress) = n*log(strain) + logk
log(100 MPa) = n*log(0.0015) + logk
log(200 MPa) = n*log(0.0025) + logk
solving these two equations,
n = 1.3570
strain hardening coefficient = 1.3570