Question

3. A stress load of 10,000 psi is initially applied to a specimen held at 900°C. Due to a change in operation, the load is doubled but the strain rate in secondary creep has to remain unchanged for safety considerations. How much would the temperature need to be lowered? The activation is 35,000 cal/mol; the gas constant R = 1.987 cal/K-mol; and the strain-rate equation reads És = Kxo’exp ( R ) 120 points)

Answer 1

Given nitial condition Q = 3.5000 call mal R=1.987 cal l komol. T = 200°C -900+273 T. -1173 K Gi: 10,000 1.35 000 Eso Kz (10,000) enp 11,987x1173) - When load is doubles - Gz = 26, - G2 = 20000 psi - Es remains same given .. Esa Kz (20,000)? explica qon) - equating ① and @ K2 (10,000) exp limona Las 1-3 sovo ) ke 1-35000 = K2020 apl.987 ) 3.5000 [ + 1173) iny +-= 7.87019xio's 1173 T1073.863 K ST 1173-1073.863 TOT 99.137°c) Auss