Question

5 a)

The size of an internal crack that can be tolerated in alloy steel 4340 tempered at 425C for a stress of 100 MPa is (use any needed data from Chapter 8): 487 mm 80.5 mm O 246 mm 40.25 mm 161 mm 287 mm 492 mm 368 mm 122 mm 413 mm

b)

c)

d)

Answer 1

4340 tempered Alloy steed at 4250 from chapter 8 Yield strength = 1420 MPa Kac = 87.4 MPa ſin Stress 100 MPa Y = 1.40 SER KA? Kec = Yo na Kec² = y²0 (Ta) 2 ² 2 4T 87.42 1 1142 x (100)x 3.14 ?? 122 mm

b) Fatigue strength after 100 million cycles in 2014-T6 Al ALLOY IS 145 MPa

c) True

d) True - SiO₂ glass - 1.38 W/m.K and SiO₂ crystals - 1.1-1.2 W/m.K