CH 14 Multiple Choice Q's

14.3 Which of the following are bulk deformation processes (three correct answers): (a) bending, (b) deep drawing, (c) extrusion, (d) forging, (e) rolling, and (f) shearing?

extrusion, forging, rolling

14.2 Which of the following are desirable properties of the work material in metal forming: (a) high ductility, (b) high tensile strength, (c) high yield strength, (d) low ductility, (e) low tensile strength, and (f) low yield strength?

high ductility, low yield strength

14.9 Increasing strain rate tends to have which one of the following effects on flow stress during hot forming of metal: (a) decreases flow stress, (b) has no effect, or (c) increases flow stress?

increases also for cold, and warm forming

14.4 Which of the following is typical of the starting work geometry in sheet metal processes: (a) high volume-to-area ratio or (b) low volume-to-area ratio?

low volume-to-area ratio

14.10 The coefficient of friction between the part and the tool in cold working tends to be (a) higher, (b) lower, or (c) no different relative to its value in hot working?

lower Coefficient of friction cold = 0.1 warm = 0.2 hot = 0.4-0.5

14.5 The flow curve expresses the behavior of a metal in which of the following regions of the stress-strain curve: (a) elastic region or (b) plastic region?

plastic region

14.8 Which of the following are advantages and characteristics of hot working relative to cold working (four correct answers): (a) fracture of workpart is less likely, (b) friction is reduced, (c) increased strength properties, (d) isotropic mechanical properties, (e) less overall energy is required, (f) lower deformation forces are required, (g) more significant shape changes are possible, and (h) strain-rate sensitivity is reduced?

- lower deformation forces are required - fracture of workpart is less likely - isotropic mechanical properties - more significant shape changes are possible

14.7 Hot working of metals refers to which one of the following temperature regions relative to the melting point of the given metal: (a) room temperature, (b) 0.2Tm, (c) 0.4Tm, or (d) 0.6Tm, where Tm = the melting temperature on an absolute temperature scale?

0.6Tm between 0.5Tm and 0.75Tm

14.6 The average flow stress is the flow stress multiplied by which of the following factors: (a) n, (b) (1+n), (c) 1/n, or (d) 1/(1+n), where n is the strain-hardening exponent?

1/(1+n)

14.1 Stresses applied in most metal forming operations are which one of the following: (a) compressive, (b) shear, or (c) tensile?

compressive