Engineering Materials Week 8 Interactvi

Satisfactory Essays
Topics: Iron, Steel, Austenite
Engineering Materials Week 8-Interactvity
11.1 Briefly explain why ferritic and austenitic stainless steels are not heat treatable.
Answer: Ferritic and austenitic stainless steels are not heat treatable since "heat treatable" is taken to mean that martensite may be made to form with relative ease upon quenching austenite from an elevated temperature.
11.2 It is possible to produce cast irons that consist of a martensite matrix in which graphite is embedded in either flake, nodule, or rosette form. Briefly describe the treatment necessary to produce each of these three microstructures.
Answer: For graphite flakes, gray cast iron is formed which is then heated to a temperature at which the ferrite transforms to austenite; the austenite is then rapidly quenched, which transforms to martensite. For graphite nodules and rosettes, nodular and malleable cast irons are first formed which are then austenitized and rapidly quenched.
11.3 What is the main difference between brass and a bronze?
Answer: Brasses principal alloying element is zinc, bronzes are alloyed with other elements such as tin, aluminum, silicon, or nickel.
11.5 On the basis of melting temperature, oxidation resistance, yield strength, and degree of brittleness, discuss whether it would be advisable to hot work or to cold work (a) aluminum alloys, and (b) magnesium alloys.
Answer: Most aluminum alloys may be cold-worked since they are ductile and have relatively low yield strengths. Magnesium alloys are normally hot-worked since they are quite brittle at room temperature.

You May Also Find These Documents Helpful

  • Satisfactory Essays

    Engineering Materials Week 8 11.5 On the basis of microstructure, briefly explain why gray iron is brittle and weak in tension. Gray iron is weak and brittle in tension because the tips of the graphite flakes act as points of stress concentration. 11.14 (a) Cite advantages of forming metals by extrusion as opposed to rolling. Two advantages of extrusion over rolling are; pieces having more complicated cross-sectional geometries may be formed and seamless tubing may be produced. (b). Cite some disadvantages…

    • 196 Words
    • 1 Page
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 3 5.1 Briefly explain the difference between self-diffusion and interdiffusion. Self-diffusion refers to movement of atoms within a pure material; interdiffusion refers to the movement of one or more kind of atoms in a heterogeneous system. 5.7 A sheet of steel 2.5mm thick has nitrogen atmospheres on both sides at 900C and is permitted to achieve a steady-state diffusion condition. The diffusion coefficient of nitrogen in steel at 900 C is 1.2 10^-10 m^2/s, and the diffusion…

    • 406 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 13 18.7 How does the electron structure of an isolated atom differ from that of a solid material? For an isolated atom, there exist discrete electron energy states each state may be occupied by two electrons, which must have opposite spins. An electron band structure is found for solid materials; within each band exist closely spaced yet discrete electron states, each of which may be occupied by , two electrons, having opposite spins. 18.15 Determine the electrical conductivity…

    • 191 Words
    • 1 Page
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 2 3.1 What is the difference between atomic structure and crystal structure? Atomic structure relates to the number of protons and neutrons in the nucleus of an atom. Crystal structure pertains to the arrangement of atoms in the crystalline solid material. 3.9 Calculate the radius of a tantalum atom, given that Ta has an BCC crystal structure, a density of 16.6 g/cm^3, and an atomic weight of 180.9 g/mol. For BCC n=2 atoms/unit cell 3.47 Below are shown three different…

    • 425 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 12 17.7 An electrochemical cell is constructed such that on one side a pure Zn electrode is I contact with a solution containing ions at a concentration of M. The other cell half consists of a pure Pb electrode immersed in a solution of ions that has a concentration of M. At what temperature will the potential between the two electrodes be +0.568 V? 17.15 (a) Cite the major differences between activation and concentration polarizations. Activation polarization is the condition…

    • 321 Words
    • 2 Pages
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 1 2.4- (a) Cite two important quantum-mechanical concepts associated with the Bohr model of the atom. Two important quantum-mechanical concepts associated with the Bohr model of the atom are that electrons are particles moving in discrete orbitals, and electron energy is quantized into shells. (b) Cite two important additional refinements that resulted from the wave-mechanical atomic model. Two important refinements resulting from the wave-mechanical atomic model are that…

    • 197 Words
    • 1 Page
    Satisfactory Essays
  • Satisfactory Essays

    Engineering Materials Week 10 14.4 (a) Compute the repeat molecular weight of polypropylene. (b) Compute the number average molecular weight for a polypropylene for which the degree of polymerization is 15,000. 14.10 Using the definitions for total chain molecule length L and average chain end-to-end distance r, for a linear polytetrafluroethylene determine: (a) the number average molecular weight for L=2000 nm. (b) the number–average molecular weight for r=15 nm. 14.19 (a) Determine the…

    • 621 Words
    • 3 Pages
    Satisfactory Essays
  • Good Essays

    Engineering Materials Week 7 10.4 (a) For the solidification of nickel, calculate the critical radius r* and the activation free energy ∆G* if nucleation is homogeneous. Values for the latent heat of fusion and surface free energy are -2.53 X10⁹ J/m3 and 0.255 J/m2. (b) Now calculate the number of atoms found in a nucleaus of critical size. Assume a lattice parameter of 0.360 nm for solid nickel at its melting temperature. (116 unit cless/critical nucleus)(4 atoms/unit cell)=464 atoms/critical…

    • 434 Words
    • 2 Pages
    Good Essays
  • Satisfactory Essays

    Engineering Materials Week 6 9.7 Given here are the solidus and liquidus temperatures for the copper-gold system. Construct the phase diagram for this system and label each region. 9.22 For 5.7 kg of a magnesium-lead alloy of composition 50 wt% Pb-50 wt% Mg, is it possible, at equilibrium, to have α and Mg₂Pb phases with respective masses of 5.13 and 0.57 kg? If so, what will be the approximate temperature of the alloy? If such an alloy is not possible, then explain why. It is not possible. From…

    • 343 Words
    • 2 Pages
    Satisfactory Essays
  • Powerful Essays

    Engineering Materials

    • 44737 Words
    • 179 Pages

    Engineering Materials Msc. Shaymaa Mahmood Introduction to Eng. Materials : Since the earliest days of the evolution of mankind , the main distinguishing features between human begins and other mammals has been the ability to use and develop materials to satisfy our human requirements. Nowadays we use many types of materials, fashioned in many different ways, to satisfy our requirements for housing, heating, furniture, clothes, transportation, entertainment, medical care, defense and all the…

    • 44737 Words
    • 179 Pages
    Powerful Essays