Mat Sel Final exam 03

Mat Sel Final exam 03 - 530.352 Final Exam 2003 NAME: _...

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530.352 Final Exam 2003 Page 1 of 14 NAME: ________________________________ MATERIALS SELECTION FALL SEMESTER 530.352 PROF. K.J. HEMKER December 16 th , 2003 : FINAL EXAMINATION (Closed book - closed notes - open mind) 1. These questions are intended to demonstrate the broad understanding that you have about material properties and from where they come. Circle the following choices that make these statements true. (2 pts ea. / 50 pts total) i) The modulus of polymers are generally [ less than ; about the same as ; greater than ] the modulus of ceramics? ii) Does the [101] direction lie in the (11-1) plane of a cubic crystal? iii) How many atoms are there per unit cell in an fcc metallic material? [ 1 ; 2 ; 3 ; 4 ; 5 ] iv) The yield strength of most pure metals is about [ the same ; 10X smaller ; 10X larger ; 1,000X smaller ; 1,000X larger ] than the theoretical strength of that material? v) Which is greater the [ compressive strength ; fatigue strength ; tensile strength ] of a ceramic material? vi) Which is greater the [ compressive strength ; fatigue strength ; tensile strength ] of a composite material? vii) In comparison with an engineering stress – engineering strain (S-e) curve, the true stress – true stress ( σ −ε ) curve for a compression test is [ the same ; shifted up and to the left ; shifted down and to the right ]? viii) The lattice friction (intrinsic resistance to dislocation motion) of a single-crystalline sample is higher for [ bcc or fcc ] metals? ix) If an alloy is over-aged such that the distance between the precipitates increases by a factor of 3, what would the strength be? [ 1/9 th ; 1/3 rd ; same ; 3X ; 9X ] x) If an alloy is heat-treated such that the grain size of the material increases by a factor of 9, what would be the effect on strength [ 1/9 th ; 1/3 rd ; same ; 3X ; 9X ]?
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530.352 Final Exam 2003 Page 2 of 14 xi) Is ferrite ( α -iron) [ bcc, fcc or hcp ] at room temperature? xii) What is the major reason that alloying elements are added to steel? [ to strengthen through precipitation hardening ; to soften through work softening ; to aide in the formation of martensite ; to solid solution strengthen ]? xiii) Of [stress intensity factor ; fracture toughness ], which is a material parameter? xiv) What are the units of stress intensity factor and fracture toughness? _______________ xv) The activation energy for creep is equal to ___________ for a large number of metals? xvi) Oxidation rates are usually either linear or parabolic. Give the equation for parabolic weight gain caused by oxidation. _______________________ xvii) The driving force for corrosion is generally measured in terms of potential voltage, which metal is more likely to corrode [Fe – or- Zn] ? Hint: how does galvanized steel work? xviii) What element is added to both stainless steel and Ni-base superalloys to improve their
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This note was uploaded on 04/08/2008 for the course MECHENG 352 taught by Professor Hemker during the Spring '08 term at Johns Hopkins.

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Mat Sel Final exam 03 - 530.352 Final Exam 2003 NAME: _...

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