Answer Happy

Pure copper has an intrinsic shear yield strength of 10 MPa. You are told that after small amount of work hardening the shear yield strength of the copper increases by 10 MPa and at this point the metal contains on average about 10-15 m/m3 of dislocations. The copper is then further work hardened such that the number of dislocations increases by a factor of 9x. Calculate the increase in the shear yield strength of the copper due to work hardening. You are also told that the Petch constant for copper is 0.11 MPam^0.5 and that the average grain size in the copper is 50 microns. Find the increase in the copper's shear yield strength due to grain boundaries. Use the intrinsic shear yield strength, together with your results to find the total shear yield strength of the copper and from there calculate the total tensile yield strength of the copper, give this as your answer, In MPa, correct to 3 significant figures. Equations (1-3) should prove useful. 0, ~ 3ty Eq (1) kp Tgb Eq (2) VD Eb Twh = 2 pa Eq (3) Answer: