Chapter 8: Problem 36
Cite three metallurgical/processing techniques that are employed to enhance the creep resistance of metal alloys.
Chapter 8: Problem 36
Cite three metallurgical/processing techniques that are employed to enhance the creep resistance of metal alloys.
All the tools & learning materials you need for study success - in one app.
Get started for freeA cylindrical component constructed from an S-590 alloy (Figure 8.30) has a diameter of 12 \(\mathrm{mm}(0.50\) in.). Determine the maximum load that may be applied for it to survive \(500 \mathrm{~h}\) at \(925^{\circ} \mathrm{C}\left(1700^{\circ} \mathrm{F}\right) .\)
A large plate is fabricated from a steel alloy that has a plane strain fracture toughness of \(55 \mathrm{MPa} \sqrt{\mathrm{m}}(50 \mathrm{ksi} \sqrt{\mathrm{in} .})\). If, during service use, the plate is exposed to a tensile stress of \(200 \mathrm{MPa}(29,000 \mathrm{psi})\), determine the minimum length of a surface crack that will lead to fracture. Assume a value of \(1.0\) for \(Y\).
The fatigue data for a ductile cast iron are given as follows: $$ \begin{array}{cc} \hline \begin{array}{c} \text { Stress Amplitude } \\ \text { [MPa (ksi)] } \end{array} & \begin{array}{c} \text { Cycles to } \\ \text { Failure } \end{array} \\ \hline 248(36.0) & 1 \times 10^{5} \\ 236(34.2) & 3 \times 10^{5} \\ 224(32.5) & 1 \times 10^{6} \\ 213(30.9) & 3 \times 10^{6} \\ 201(29.1) & 1 \times 10^{7} \\ 193(28.0) & 3 \times 10^{7} \\ 193(28.0) & 1 \times 10^{8} \\ 193(28.0) & 3 \times 10^{8} \\ \hline \end{array} $$ (a) Make an \(S-N\) plot (stress amplitude versus logarithm cycles to failure) using these data. (b) What is the fatigue limit for this alloy? (c) Determine fatigue lifetimes at stress amplitudes of \(230 \mathrm{MPa}(33,500 \mathrm{psi})\) and \(175 \mathrm{MPa}\) \((25,000 \mathrm{psi})\) (d) Estimate fatigue strengths at \(2 \times 10^{5}\) and \(6 \times 10^{6}\) cycles.
Steady-state creep rate data are given in the following table for nickel at \(1000^{\circ} \mathrm{C}(1273 \mathrm{~K})\) : $$ \begin{array}{cc} \hline \dot{\epsilon}_{s}\left(\boldsymbol{s}^{-1}\right) & \boldsymbol{\sigma}[\boldsymbol{M P a}(\boldsymbol{p s i})] \\ \hline 10^{-4} & 15(2175) \\ 10^{-6} & 4.5(650) \\ \hline \end{array} $$ If it is known that the activation energy for creep is \(272,000 \mathrm{~J} / \mathrm{mol}\), compute the steady-state creep rate at a temperature of \(850^{\circ} \mathrm{C}\) (1123 K) and a stress level of \(25 \mathrm{MPa}\) (3625 psi).
A polystyrene component must not fail when a tensile stress of \(1.25 \mathrm{MPa}(180 \mathrm{psi})\) is applied. Determine the maximum allowable surface crack length if the surface energy of polystyrene is \(0.50 \mathrm{~J} / \mathrm{m}^{2}\left(2.86 \times 10^{-3}\right.\) in.-lb \(\left._{\mathrm{t}} / \mathrm{in} .^{2}\right)\). Assume a modulus of elasticity of \(3.0 \mathrm{GPa}\) \(\left(0.435 \times 10^{6} \mathrm{psi}\right)\)
What do you think about this solution?
We value your feedback to improve our textbook solutions.