Page 170 - Manufacturing Engineering and Technology - Kalpakjian, Serope : Schmid, Steven R.

Quantitative Problems |49

5.l I. What are the major alloying elements in tool and die 5.|4. What is high-speed steel?
steels and in high-speed steels? 5.I5. What is TRIP? I WIP?
5.12. How does chromium affect the surface characteristics 5.16. What are the applications of advanced high-strength
of stainless steels?
steels?
5.13. What kinds of furnaces are used to refine steels?

QUALITATIVE PROBLEMS

5.17. Identify several different products that are made of 5.27. In Table 5.8, D2 steel is listed as a more common tool
stainless steel, and explain why they are made of that material. and die material for most applications. Why is this so?
5.l8. Professional cooks generally prefer carbon-steel to 5.28. List the common impurities in steel. Which of these
stainless-steel knives, even though the latter are more popular are the ones most likely to be minimized if the steel is melted
with consumers. Explain the reasons for those preferences. in a vacuum furnace?
5.19. Why is the control of the structure of an ingot 5.29. Explain the purpose of the oil shown at the top left of
important? Fig. 5.4a given that the molten-steel temperatures are far
5.20. Explain why continuous casting has been such an above the ignition temperatures of the oil.
important technological advancement. 5.30. Recent research has identified mold-surface textures
5.21. Describe applications in which you would not want to that will either (a) inhibit a solidified steel from separating
use carbon steels. from the mold or (b) force it to stay in contact in continuous
casting. What is the advantage of a mold that maintains inti-
5.22. Explain what would happen if the speed of the
mate contact with the steel?
continuous-casting process shown in Fig. 5.4a is (a) higher
or (b) lower than that indicated, typically 25 mm/s. 5.31. Identify products that cannot be made of steel, and
explain why this is so. (For example, electrical contacts com-
5.23. The cost of mill products of metals increases with
monly are made of gold or copper, because their softness
decreasing thickness and section size. Explain why.
results in low contact resistance, whereas for steel, the con-
5.24. Describe your observations regarding the information
tact resistance would be very high.)
given in Table 5.8.
5.32. List and explain the advantages and disadvantages of
5.25. How do trace elements affect the ductility of steels?
using advanced high-strength steels.
5.26. Comment on your observations regarding Table 5.1.

QUANTITATIVE PROBLEMS

5.33. Refer to the available literature, and estimate the cost nealed 303 stainless steel, (b) normalized 8620 steel, (c) as-
of the raw materials for (a) an aluminum beverage can, (b) a rolled 1080 steel, (d) any two aluminum alloys, (e) any brass
stainless-steel two-quart cooking pot, and (c) the steel hood alloy, and (f) pure copper.
of a car. 5.37. The endurance limit (fatigue life) of steel is approxi-
5.34. In Table 5.1, more than one type of steel is listed for mately one-half the ultimate tensile strength (see Fig. 2.17), but
some applications. Refer to data available in the technical lit- never higher than 700 MPa. For iron, the endurance limit is
erature listed in the bibliography, and determine the range of 40% of the ultimate strength, but never higher than 170 MPa.
properties for these steels in various conditions, such as cold Plot the endurance limit vs. the ultimate strength for the steels
worked, hot worked, and annealed. described in this chapter and for the cast irons shown in Table
5.35. Some soft drinks are now available in steel cans (with 12.3. On the same plot, show the effect of surface finish by
aluminum tops) that look similar to aluminum cans. Obtain plotting the endurance limit, assuming that the material is in
one of each type, weigh them when empty, and determine the as-cast state. (See Fig. 2.29.)
their respective wall thicknesses. 5.38. Using the data given in Table 5.3, obtain the power-
|]5.36. Using strength and density data, determine the law curves for the advanced high-strength steels shown and
minimum weight of a 600-mm-long tension member that plot the curves. Compare these materials with those given in
must support a load of 450 kg, manufactured from (a) an- Table 2.6.