Loose Leaf For Foundations Of Materials Science And Engineering
6th Edition
ISBN: 9781260049169
Author: William Smith, Javad Hashemi, Prof.
Publisher: McGraw-Hill Education
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Chapter 4.8, Problem 65SEP
To determine
Explain how you would accomplish an application that requires that the diameter of the bar be reduced and the grain dimensions are longer along the longitudinal axis of the bar.
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The lower yield point for a certain plain carbon steelbar is found to be 135 MPa, while a second bar of the samecomposition yields at 260 MPa. Metallographic analysisshows that the average grain diameter is 50μm in the firstbar and 8μm in the second bar.a. Predict the grain diameter needed to cause a loweryield point of 205 MPa.b. If the steel could be fabricated to form a stablegrain structure of 500 nm grains, what strengthwould be predicted?c. Why might you expect the upper yield point to bemore alike in the first two bars than the lower yieldpoint?
Q3 contd.
(d) The yield strength values of pure aluminium (Al) and pure copper (Cu) are 25 MPa and 20
MPa, respectively; whereas the yield strength values of cold rolled Al-Mn-Mg alloy and cast
60-40 Brass (60% Cu, 40% Zn) are 200 MPa and 105 MPa, respectively. With aid of
schematics, explain the main mechanisms account for the increases in the strengths.
(e) A cylindrical tie rod with a diameter of 18.4 mm is subjected to cyclic loading. The stress range
is +/- 200 kN. Figure Q3.3 shows the S-N curve of the material of which the rod is made, how
many cycles will this rod survive?
Stress amplitude
O₂ (MPa)
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
10²
10³
104
4340 low-alloy steel
Stress ratio = -1
Fig. Q3.3
105
106
Number of cycles to failure, Nf
107
108
A hypothetical metal alloy has a grain diameter of 2.4 x 10-2 mm. After a heat treatment at 575°C for 500 min, the grain diameter
has increased to 8.1× 10-2 mm. Compute the time required for a specimen of this same material (i.e., do = 2.4 × 10-2 mm) to achieve
a grain diameter of 5.5 × 10-2 mm while being heated at 575°C. Assume the n grain diameter exponent has a value of 2.2.
Chapter 4 Solutions
Loose Leaf For Foundations Of Materials Science And Engineering
Ch. 4.8 - Prob. 1KCPCh. 4.8 - Define the homogeneous nucleation process for the...Ch. 4.8 - In the solidification of a pure metal, what are...Ch. 4.8 - In the solidification of a metal, what is the...Ch. 4.8 - During solidification, how does the degree of...Ch. 4.8 - Distinguish between homogeneous and heterogeneous...Ch. 4.8 - Describe the grain structure of a metal ingot that...Ch. 4.8 - Distinguish between equiaxed and columnar grains...Ch. 4.8 - How can the grain size of a cast ingot be refined?...Ch. 4.8 - Prob. 10KCP
Ch. 4.8 - Prob. 11KCPCh. 4.8 - Prob. 12KCPCh. 4.8 - Distinguish between a substitutional solid...Ch. 4.8 - What are the conditions that are favorable for...Ch. 4.8 - Prob. 15KCPCh. 4.8 - Prob. 16KCPCh. 4.8 - Prob. 17KCPCh. 4.8 - Prob. 18KCPCh. 4.8 - Describe the structure of a grain boundary. Why...Ch. 4.8 - Describe and illustrate the following planar...Ch. 4.8 - Prob. 21KCPCh. 4.8 - Describe the optical metallography technique. What...Ch. 4.8 - Prob. 23KCPCh. 4.8 - Prob. 24KCPCh. 4.8 - Prob. 25KCPCh. 4.8 - Prob. 26KCPCh. 4.8 - Prob. 27KCPCh. 4.8 - Prob. 28KCPCh. 4.8 - Prob. 29KCPCh. 4.8 - Prob. 30KCPCh. 4.8 - Prob. 31KCPCh. 4.8 - Calculate the size (radius) of the critically...Ch. 4.8 - Prob. 33AAPCh. 4.8 - Prob. 34AAPCh. 4.8 - Calculate the number of atoms in a critically...Ch. 4.8 - Prob. 36AAPCh. 4.8 - Prob. 37AAPCh. 4.8 - Prob. 38AAPCh. 4.8 - Prob. 39AAPCh. 4.8 - Prob. 40AAPCh. 4.8 - Prob. 41AAPCh. 4.8 - Prob. 42AAPCh. 4.8 - Determine, by counting, the ASTM grain-size number...Ch. 4.8 - Prob. 44AAPCh. 4.8 - For the grain structure in Problem 4.43, estimate...Ch. 4.8 - Prob. 46AAPCh. 4.8 - Prob. 47SEPCh. 4.8 - Prob. 48SEPCh. 4.8 - Prob. 49SEPCh. 4.8 - Prob. 50SEPCh. 4.8 - In Chapter 3 (Example Problem 3.11), we calculated...Ch. 4.8 - Prob. 52SEPCh. 4.8 - Prob. 53SEPCh. 4.8 - Prob. 54SEPCh. 4.8 - Prob. 55SEPCh. 4.8 - Prob. 56SEPCh. 4.8 - Prob. 57SEPCh. 4.8 - Prob. 58SEPCh. 4.8 - Prob. 59SEPCh. 4.8 - Prob. 60SEPCh. 4.8 - Prob. 61SEPCh. 4.8 - Prob. 62SEPCh. 4.8 - Prob. 63SEPCh. 4.8 - Prob. 64SEPCh. 4.8 - Prob. 65SEPCh. 4.8 - Prob. 66SEP
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- Question-6. For solidification of a piece of FCC-metal at 860 °C. The melting point of the metal is 1260 °C. The latent heat of fusion and surface free energy are -2.16 x108 J/m³ and 0.126 J/m², respectively. If nucleation is homogeneous, answer the following questions: (a) Compute the critical radius r* in nm (b) Compute the activation free energy AG* in J (c) If the lattice parameter is 0.26 nm at the melting temperature, compute the number of atoms found in a nucleus of critical size (d) Compute the critical radius at the supercooling degree of 260 K.arrow_forwardThe lower yield point for a certain plain carbon steel bar is found to be 135 MPa, while a second bar of the same composition yields at 260 MPa. Metallographic analysis shows that the average grain diameter is 50 µm in the first bar and 8 µm in the second bar. Predict the grain diameter needed to cause a lower yield point of 205 MPa.arrow_forwardIn a sample made of an alloy that has not been subjected to cold forming, the average grain size is 0.040 mm. You are asked to reduce the average grain diameter of this sample to 0.010 mm. Is this possible? If possible, explain the procedures you will apply. If not possible, state why it is not possible.arrow_forward
- | Describe in your own words the three strengthening mechanisms discussed in this chapter (i.e., grain 5. size reduction, solid-solution strengthening, and strain hardening). Explain how dislocations are involved in each of the strengthening techniques.arrow_forward3. A 30-cm long, 12-mm diameter carbon steel rod was subjected to 15.5 kN of tension. Calculate (a) the stress and strain in the rod, (b) the amount that it stretches, (c) its change in diameter, and (d) its stiffness (k=EA/L). (e) If the force was only 4.5 kN, by what amount would the rod have stretched?arrow_forwardNote: Answer Should be not so long. Need straight forward Answer. For minimizing (1) dislocation creep and (ii) diffusion creep, state in each case whether a metal with a small grain size or a large grain size would be the most suitable, giving reasons for your answers.arrow_forward
- The flow stress of a coarse-grained dilute copper alloy increased from 2 to 55 MPa when the dislocation density was increased from a low value of 10 cm via cold working to a modest value of 100 cm2. Calculate the flow stress for this alloy when heavy cold working introduces a dislocation density of 10¹2 cm². An equation similar to the Hall-Petch equation has been proposed for dislocations, and is: Tflow To ka Paisl where Tflow is the flow stress (i.e., the force per unit area necessary to get plastic deformation), pdisi is the dislocation density (the dislocation line length per unit volume), and To and ka are constants for a given material. The easiest way to solve this problem is to put values into this equation twice, subtract one expression from the other, and solve for ka. Then enter your value of ka into either original equation to determine To. Keep track of units, and then solve the problem stated above.arrow_forwardIn the Figure below, the tensile breaking strength, (sigma mark)tenstile-breaking = 140 Mpa breaking strength at compression (sigma mark)compression-breaking = 460 Mpa pouring Machine part made of iron is shown. to the piece P=25 kN forces are acting. piece for t=26 mm Calculate reliability according to Coulomb - Mohr theory ?arrow_forwardCalculate the dislocation spacing of a low-angle tilt boundary in aluminumfor θ = 0.5◦. Take G = 26.1 GPa, v = 0.345, and rAl = 0.143 nm.arrow_forward
- A cold-worked brass specimen of average grain size 0.02 mm has a xield strength of 160 MPa Estimate the xield strength of this allov after it has been heat treated and the value of ky is 12.0 MPa-mm!2. (10)arrow_forwardDescribe in your own words the three strengthening mechanisms discussed in this chapter (i.e., grain size reduction, solid-solution strengthening, and strain hardening). Be sure to explain how dislocations are involved in each of the strengthening techniques.arrow_forwardThe yield strength for an alloy that has an average grain diameter of 4.1 × 10-2 mm is 131 MPa. At a grain diameter of 7.6 × 10-3 mm, the yield strength increases to 246 MPa. At what grain diameter, in mm, will the yield strength be 236 MPa?arrow_forward
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