ME 3701 Final Example With Questions And Verified Answers.

password: - correct answer materialslab strain hardening - correct answer occurs following yielding of ductile metals chauvenets criterion - correct answer identify outliers in repeated measures data, and determine if the data points can be eliminated from analysis only rank data-> calculate average-> mean deviation(di)-> standard deviation-> compare to chart using number of readings(n)-> if points are rejected, calculate new average without the point(s) -> calculate new % below Xi-> graph - correct answer Steps to Chauvenets Criterion the data set follows a normal (gaussian) distribution - correct answer repeated measured data is often plotted on probability paper to determine if modulus of resilience - correct answer the ability of a material to absorb energy elastically metallographic samples - correct answer must be washed thoroughly between grinding and polishing to avoid station contamination nanometers - correct answer measurement for X-ray wavelength yield strength - correct answer beginning of plastic deformation Charpy and Izod testing - correct answer used to measure toughness both use V notched samples Charpy test: specimen placed horizontal with v-notched faced away from the hammer Izod: specimen placed vertical with v-notch facing toward hammer - correct answer Difference between Charpy and Izod testing Rockwell testing - correct answer used to determine HARDNESS of steel-- consists of measuring additional depth to which an indenter is forced by a heavy(major) load beyond the depth of previously applied light (minor) load Difference between Rockwell and Brinell Hardness Tests? Rockwell- hardness is determined by measuring the DEPTH of the indentation Brinell- hardness is measured by indentation SIZE - correct answer Difference between Rockwell and Brinell Hardness Tests? eliminates backlash in the load train, and causes indenter to break through slight surface roughness and to crush particles of foreign matter--> much greater accuracy in test - correct answer What is the benefit of first applying a minor load to the specimen before the major load in Rockwell hardness testing?eliminates backlash in the load train, and Aluminum alloys, Copper Alloys, soft steels, malleable iron - correct answer When do you use B scale for Hardness Testing? Steel, and other metals harder than 100 HRB - correct answer When do you use C scale for Hardness Testing? 60 HRC - correct answer How do you write the result of a hardness test on the C scale with a reading of 60? 80 HRB - correct answer How do you write the result of a hardness test on the B scale with a reading of 80? Austempering - correct answer used to facilitate formation of bainite (hard and brittle microstructure), quench in salt bath then cool at room temp Annealing - correct answer applied to relieve internal stresses and increase strength through recrystallization, age hardening (without over aging) - correct answer formation of coherent precipitates increases the hardness and strength of a material solution treatment- to minimize segregation in the alloy, quenching - to create a supersaturated solid solution, aging- to facilitate the formation of coherent precipitates which strengthen the alloy by interfering with dislocation movement - correct answer steps for heat treatment (precipitation hardening) of Al alloy and their purpose best = 3wt%cu, worst=pure aluminum this is because to hardening comes from solid solution that decreases solid solubility as temp decreases.. this requires being the alpha region (homogeneous solid solution) and alpha + theta region which occurs around 3-4wt%cu - correct answer which is best and worst for precipitation hardening out of pure aluminum, 3wt%cu, and 8wt%cu and WHY hardness - correct answer measure of materials resistance to localized plastic deformation (e.g., small dent or scratch) toughness - correct answer measure of the amount of energy a material can absorb before fracture hardenability (use Jominy End Quench Test) - correct answer ability to become more hard by quenching minor load in rockwell test - correct answer flattens the surface and ensures no debris causes errors in reading ductile fracture - correct answer more energy is absorbed because material is allowed to strain more while withstanding higher forces, energy under curve is greater