Question

Suppose the tensile yield strength of a bcc metal varies with absolute temperature (7) as oy = (2000 - 47) MN/m², and the metal's crack propagation stress varies with T as Op = (600 +27) MN/m². Calculate the Mode II to Mode III fracture-transition temperature that would be found in tensile testing of this metal.

Answer 1

Given that yield strength Ty = 2000 - 4T Manlent Metal cracking propagation Shress F = 600+27 MNIM Now we are setting the yield strength is equal to the metal cracking propagation stress e Ty = TE 1 2000-4T = 600 + 2 T 2000-600 = 4T + 2T 1400 = 67 T- 1400 T => 233.33K. * If the temperature below that find (ien 233.33k) that we find fracture in concurrent with yielding ie, Mode 11 fracture. * If the temperature above that find (14 233 334 that we find, metal macroscopically flows before tracture ie, Mode 111 tracture.