CH 18: Fundamentals of Metal Forming
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 is required, (g) more significant shape changes are possible, and (h) strain-rate sensitivity is reduced?
Answer. (a), (d), (f), and (g).
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?
Answer. (b).
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?
Answer. (b).
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?
Answer. (b).
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?
Answer. (c), (d), and (e).
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?
Answer. (c).
Hot working of metals refers to which one of the following temperature regions relative to the melting point of the given metal on an absolute temperature scale: (a) room temperature, (b) 0.2Tm, (c) 0.4Tm, or (d) 0.6Tm?
Answer. (d).
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?
Answer. (d).