Exam 3 Cheat Sheet

pdf

School

University of Illinois, Urbana Champaign *

*We aren’t endorsed by this school

Course

300

Subject

Mechanical Engineering

Date

Oct 30, 2023

Type

pdf

Pages

2

Uploaded by ChancellorStraw8147

Report
[Exam 3] lever rule - relative amount of each phase: ࠵? !"#$ = % !"#$% &% "&"%"’( % !"#$% &% ()*% | ࠵? ’()*$ = % "&"%"’( &% ()*% % !"#$% &% ()*% - slow cooling formation of equilibrium structures | rapid cooling formation of cored(non-equilibrium) structures Fe(iron) – C(carbon) eutectic system - ࠵?: Austenite | ࠵?: Ferrite | ࠵?࠵? + ࠵?: Cementite (metastable | decomposes to ࠵? & ࠵? over long period of time) | ࠵?: carbon (graphite) | Pearlite - ࠵? → FCC interstitial hole, 0.052 nm, up to 2% carbon is soluble | ࠵? BCC interstitial hole, 0.036 nm, up to 0.02% carbon FCC more tightly packed & less interstitial volume, but the individual spaces larger higher solubility of Carbon dispersion strengthening: small, spherical and well distributed dispersed phase blocks dislocation motion strength - eutectic point (liquid to solid): 4.30 wt% C, 1147 °࠵? | eutectoid point (solid to another solid): 0.76 wt% C, 727 °࠵? @ eutectoid point: Pearlite - alternating layers of ࠵? (Ferrite) and ࠵?࠵? + ࠵? (Cementite) | micro-constituent, not a phase - eutectic systems that cool through the eutectic or eutectoid transformation show layered lamellar structure within grains - hypo-eutectoid (left): proeutectoid ferrite & pearlite | hyper-eutectoid (right): proeutectoid cementite & pearlite Ferrous metals - steels: < 1.4 wt% C | cast irons: > 2.1 wt% C (commonly 3~4.5 wt% C b/c low melting and brittle easiest to cast) - for steels, as carbon content , strength & cost , and ductility - naming: last two digits carbon content in hundredths of a percent by weight - 304 stainless steel (0.08% C, 18-20% Cr, 8-10.5% Ni): very ductile and corrosion resistant ductility from low carbon and high nickel content | corrosion resistance from high chromium content -10xx:plain carbon | 11xx:plain carbon (resulfurized) | 15xx:Mn(10~20%) | 40xx:Mo(0.2~0.3%) | 43xx:Ni,Cr,Mo | 44xx:Mo(0.5%) | SS:Cr(11%) Crystal nucleation - volume energy: ࠵? , = ∆. * (0 + &0) 0 + | ࠵? 2 : melting temp | ∆࠵? # : latent heat of fusion - critical radius: ࠵? = 4− 450 + ∆. * 6 7 6 0 + &0 8 | activation energy: ∆࠵? = 4 6785 , 0 + - +∆. * - 6 7 6 (0 + &0) - 8 | ࠵?: surface free energy As degree of undercooling (࠵? 2 − ࠵?) , the formation of more, small nuclei are enabled - solidification rate is a result of nucleation and growth of crystals large grain size: ࠵? just below ࠵? 9 , nucleation rate low, growth rate high small grain size: ࠵? far below ࠵? 9 , nucleation rate high, growth rate low Isothermal transformation diagrams (TTT curves) - isothermal process: material is rapidly cooled to a fixed temperature, which is then maintained throughout the reaction - even though composition is fixed, cooling path can affect microstructure coarse pearlite: relatively thick layers of cementite | Formed at higher ࠵? (softer) fine pearlite: relatively thin layers of cementite | Formed at lower ࠵? (harder) - when cooling path below the “nose” of TTT curve bainite formed Bainite: microconstituent | very fine microstructure of needlelike ࠵?࠵? + ࠵? (Cementite) in ࠵? (Ferrite) matrix pearlite and bainite are unlikely to transform to each other | bainite does not admit proeutectoid phases - when material is very rapidly cooled (quenched) to a low temp diffusion is effectively prevented & martensite formed Martensite: non equilibrium phase metastable | ࠵? (Ferrite) and ࠵?࠵? + ࠵? (Cementite) are not allowed to form FCC ࠵? (Austenite) reconfigures to BCT (hard & extremely brittle) with interstitial carbon if ࠵? ↑ and diffusion is enabled, it will decompose to ࠵? (Ferrite) and ࠵?࠵? + ࠵? (Cementite) tempering: holding metal at a high temp but below ࠵? 9 for some time period enables diffusion and transformation improves ductility and maintains high hardness | extremely small ࠵?࠵? + ࠵? (Cementite) spheres in ࠵? (Ferrite) matrix - effect of alloying on TTT curves changing the amount of alloying agents (including carbon) affects shape and structure of curves transition temperatures shift (usually decrease) and new phases appear alloys often applied to ease heat treatment of metals Continuous cooling transformation (CCT) curves - isothermal cooling is not practical | metals usually allowed to cool to room temp continuously | bainite not produced w CC - CCT curves shifted lower and to the right compared with TTT Thermal processing – Quenching (to improve hardness of steel) - best properties are achieved when high martensite content is obtained (minimize pearlite and bainite) - problem: cooling not uniform within specimen: a range of microstructures are obtained - successful heat treatment depends on: alloy type | quench type | size and shape quench type (low to high severity of quench & hardness): air < oil < water geometry (as surface-to-volume ratio , cooling rate & hardness ): center < surface Hardenability test – Jominy end quench (test to measure the ability of metal to form martensite) - hardness as distance from quenched end | alloy steels enable more practical heat treatment
Thermal processing - lower temp: all metals (usually done for lower carbon steels) stress relief: reduce stress caused by plastic deformation, nonuniform cooling, phase transform process anneal: negate effect of cold working by recovery/recrystallization - higher temp: steels (usually done for higher carbon steels) normalized: refined worked steel with large grains. Air cool after heating to get ࠵? (Austenite) to make fine pearlite full anneal: make soft steels for good forming and machining. Heat to get ࠵? , then slow cool to get coarse pearlite spheroidize: make very soft steels for good machining. Heat just below ࠵? 9 and hold for 15~25 hours. Trends with steel processes - strength & hardness (increasing order): spheroidite, coarse pearlite, fine pearlite, bainite, tempered martensite, martensite - ductility (decreasing order): spheroidite, coarse pearlite, fine pearlite, bainite, tempered martensite, martensite Corrosion (consuming chemical reaction between a metal and its environment – dissolution of metal into solution) - driving force: electrical potential ( ࠵? $:$ ) | ࠵? = −࠵?࠵?࠵? $:$ | ࠵?: Faraday constant (96500 Coulombs/mole) | ࠵?: # of electrons - anode(+): gives up electrons (oxidation) | cathode(-): gains electros (reduction) | ࠵?࠵? = −log (࠵? . . ) - standard EMF series (solutions at 1M solutions and gasses, 1 atm, 25 °࠵? ) higher potential reduces (noble) and lower potential oxidizes (active) | if ࠵? $:$ > 0 , reaction is spontaneous anode reactions (metals | oxidation) oxidation to cations: ࠵? ; → ࠵? <2 + ࠵?࠵? & oxidation to metal hydroxide: ࠵? ; + ࠵?࠵? 4 ࠵? → ࠵?(࠵?࠵?) 2 + ࠵?࠵? < + ࠵?࠵? & oxidation to anions: ࠵? ; + ࠵?࠵? 4 ࠵? → ࠵?࠵? = 2&4= + 2࠵?࠵? < + ࠵?࠵? & cathode reactions (reduction) hydroxyl formation: ࠵? 4 + 2࠵? 4 ࠵? + 4࠵? & → 4(࠵?࠵?) & hydroxyl formation ( ࠵? 4 free environment): 2࠵? 4 ࠵? + 2࠵? & → 2(࠵?࠵?) & + ࠵? 4 ࠵? 4 formation ( ࠵? 4 free & acidic environment): 2࠵? < + 2࠵? & → ࠵? 4 water formation (acidic environment): ࠵? 4 + 4࠵? < + 4࠵? & → 2࠵? 4 ࠵? - ࠵? > − ࠵? ? = ࠵? ; > − ࠵? ; ? @0 AB ࠵?࠵? 7 ? > 8 | ࠵?: 8.314 J/mole | ࠵?: 96500 Coulombs/mole | ࠵?: Kelvin | ࠵?: # of electrons in oxidation - Passivation: Al and Cr are non-corroding in ambient environments and steel in concrete | complete passivation: % Cr > 8% Ceramics - cat-an ion r ratio: /(.) ’(2) | ࠵? = C 3&"% /)(( D 3&"% /)(( | packing factor: ࠵?࠵?࠵? = D ’(( ’%5+6 "& 3&"% /)(( D 3&"% /)(( - a combination of one or more metallic elements with a non-metal | primarily ionic bonding with some covalent - strong bonds with non-metal insoluble in water | common ceramics: silica ( ࠵?࠵?࠵? 4 ), alumina ( ࠵?࠵? 4 ࠵? + ) - properties: good hardness | high strength | good thermal stability | good chemical resistance | low conductivity | brittle - ceramic crystal structures inherently contain defects | EQ concentration of defects depends on temperature mech. properties: brittle (notch sensitive with low ࠵? E% ) | superior temp stability and creep properties - glass ( ࠵?࠵?࠵? 4 ): melted and shaped or molded | traditional ceramics ( ࠵?࠵?࠵? 4 & ࠵?࠵? 4 ࠵? + ): sintered - sintering: powder compacted, partially melted, then cooled | grain boundary diffusion - porosity affects tens., comp. strength & elastic constants | ࠵? F = ࠵? ; ࠵? &AF | ࠵? = ࠵? ; (1 − 1.9࠵? + 0.9࠵? 4 ) | ࠵?: % I:’:J($? 6;; - silicate structures | amorphous: silica glass chemically stable and unreactive: borosilicate “pyrex” silicate tetrahedron: not electrically neutral (+4) | corrected with counter cations | bonds to another and molecular groups fiber-line chains asbestos | layered 2-D sheets mica, talc, clays | 3-D crystal structure quartz, cristobalite - alumina octahedron: octahedral crystal structure | linked by sharing edges| crystalline with hexagonal symmetry LAB - bending: ࠵? = K - (+L&MK) 64E F N | ࠵? = =* , 64 | ࠵? ? = +F 7 K =* - | ࠵? O = +F +’8 K =* - |torsion: ࠵? = 4 0 P L Q 6 6 R |࠵? = 2(1 + ࠵?)࠵?|࠵? = 8’ 9 4 |࠵? ? = 2࠵? ? = 2 0 7 R | ࠵? 0 = 0 +’8 R - bending: 1045-mill scale flakes | Al-orange-peel | PMMA-fracture |torsion: 1045 & Al - fracture (ductile) | PMMA - 45 ° fracture (brittle) - notch: ࠵? ? S = +F 7 : K =* - | ࠵? $ = (@ ; ) 3&&5%/$)< (@ ; ) &5%/$)< | ࠵? = 1 − T 7 T 7 : | round: ࠵? U , sharp: ࠵? ? , up ( ↑) : comp., down( ↓) : tens.|1045:flat, Al: shear lips - plate pen.: PMMA ( fracture D, P & energy) - 100 < RT < 0 | HDPE ( deformation & shear lips, P & ener.) - 0 < RT < 100 - charpy: 1045 ( mill scale, shear lips, energy.) - 0 < RT < 100 | Al – shear lips at all temp. - fracture toughness: ࠵? = K = | ࠵? V = F O√= ࠵?(࠵?) | ࠵? X = F = O√= ࠵?(࠵?) | ࠵?, ࠵? ≥ 2.5 4 Y = T 7 6 4 | 2024: I | 7075: III - creep: ࠵? = ∆! ! > | ࠵? = F Z = 6;[ Z | ࠵?̇ JJ = ∆\ ∆$ | ࠵?̇ JJ = ࠵?࠵? 2 | log 6; ࠵?̇ JJ = log 6; ࠵? + ࠵? log 6; ࠵? - strain ↑: lead < HDPE | ࠵? = 1.78 constant for HDPE, ࠵? = 1.08~5.78 for lead - the higher the strain rate, the shorter the extension of a specimen
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help

Browse Popular Homework Q&A

Q: Propose an efficient synthesis for the following transformation: The transformation above can be…
Q: Using c++ Write a function called penultimateValue that accepts a 1D array of integers "a" and an…
Q: Using c++, Write a function that determines the index of the second to the last occurrence of a…
Q: 13. Which of the following is the major product of the reaction? HBr (excess) a) d) Br CH₂C=CH Br b)…
Q: The graph shows =, f(0) (solid) and r = g(e) (dashed), both graphed in polar coordinates. = [3, 4],…
Q: Does high temperature increase plant respiration? Why or why not?
Q: O Add and simplify. Ei (-8p'+4p5-8p+9)+(-6p² + 8p³ + p²) Check Answer X Ⓒ2022 Mc
Q: Given Principal $18,000, Interest Rate 9%, Time 240 days (use ordinary interest) Partial payments:…
Q: 7. Consider the network from the problem running distance-vector routing has already achieved…
Q: Saturated acetone vapor enters a heat exchanger always a rate of v1=1.30L/s at p1=1 atm and emerges…
Q: What type of reset does the following code use? module FrameChecker ( input logic clk, input logic…
Q: implement the BitReverser module, ha
Q: The region below is bounded by y = 3√, y = 0 and x = 4 8 7 6 5 4 3 2 1 -1 -2 3 5 6 7 8 This region…
Q: A kidney cell and a skin cell in the same individual will contain _____________. Select one: a.…
Q: Cesar Rego Computers, a Mississippi chain of computer hardware and software retail outlets, supplies…
Q: Glaciers exist on earth where they can? Melt Boil Freeze Burn
Q: A ________ strategy involves accurately measuring all the factors needed to predict sales and…
Q: What is the best possible coefficient of performance COPref for a refrigerator that cools an…
Q: If a solution has a [H+]=1 x 10 -3 M, what is the pOH of that solution? Group of answer choices 11…
Q: The pound is an English unit of measure; its SI counterpart is the newton kilogram joule momentum
Q: Evaluate the integral √² (²2/1 + ²)² = 24 dr= 24 7 dr.
Q: Conversion of Units.   Complete any four from below. Must show all steps used to get your final…