Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
40 Cards in this Set
- Front
- Back
|
What are some advantages to using aluminum vs steel?
|
more corrosion resistant
better heat/electrical conductor 1/3 weight of steel 1/3 stiffness of steel |
|
|
Why has aluminum only been used for the past 60 yrs as an engineering metal?
|
Because of the inertness of Al cmpds, it took 60 years of research to find an economically acceptable way to make Al from ore
|
|
|
What % of the earth's crust is Al?
|
8%
|
|
|
What is the crystalline structure of Al?
|
FCC
|
|
|
weight (density) of Al
|
low density
|
|
|
thermal/electrical conductivity of Al
|
higher conductivity than Cu per unit mass
|
|
|
resistance to corrosion of Al
|
good for applications involving atmospheric corrosion resistance
|
|
|
Is Al magnetic?
|
Al is non
magnetic |
|
|
formability and machinability of Al
|
good formability and easily machined
|
|
|
weldability of Al
|
most Al alloys are weldable
|
|
|
5052-H
|
A95052
H: strain hardened |
|
|
6061-T6
|
A96061
T: thermally treated T6:furnace soln heat treated, quenched, furnace aged |
|
|
7075-O
|
A97075
O: annealed (wrought alloys only) |
|
|
What is a common Al extrusion product that could be considered important for Naval Architects?
|
sailboat masts
|
|
|
Explain how Al's limited solubility at room T with alloy contributes to it's ability to strengthen/harden
|
at room T: solubility <0.02% and precipitation hardening is possible
|
|
|
Potential use of Al (wrt to corrosion resistance) in salty air
|
Al has a extremely low corrosion rate in salty air
high corr. rate the 1st 2 years but afterwards, surface is covered with oxide corr. product (patina) and has a low corr. rate |
|
|
Potential use of Al (wrt to corrosion resistance) in seawater
|
5xxx series acceptable
prone to pitting requires cathodic protection/coatings stainless steel fasteners/attachments are good |
|
|
Potential use of Al (wrt to corrosion resistance) in water (piping)
|
not widely used in plumbing systems b/c H2O containing heavy metal ions (Cu, Pb, Ni, Tin) leads to pitting
|
|
|
How are pure Ni and Steel similar?
|
similar:
melting pt appearance modulus of elasticity density coeff of thermal expansion |
|
|
How are pure Ni and Steel different?
|
Ni has 2x better thermal/electical conductor
magnetic permeability characteristics |
|
|
What are some uses of Ni?
|
(nickel-based super alloys) jet engine parts
high T electrical conductors and wire terminals magnetic shielding of electronic devices tape recording heads (nichrome) resistance heating elements |
|
|
What is the UNS # and primary alloys of Monel 400?
|
N04400
Ni, Cu |
|
|
What is the UNS # and primary alloys of Inconel 625?
|
N06625
Ni, Cr |
|
|
What is the UNS # and primary alloys of Incoloy 825?
|
N08825
Ni, Cr, Fe |
|
|
What are characteristics of Monel 400?
|
resistant to neutral waters, seawater, and some acids
resists errosion corrosion to high velocities strong passive film may cause severe galvanic attack of less noble materials when coupled suffers uniform corrosion, pitting, and crevice attack uses: valves, pumps, prop shafts, fixtures, fasteners, handling acids |
|
|
What are characteristics of Inconel 625?
|
high strength and toughness to 1800F (980C)
resists erosion corrosion to high velocities and highly resistant to most forms of attack uses: wire rope, propeller blades, fittings, springs, fasteners, parts where little/no corrosion can be accepted not susceptible to carbide precipitation during welding and subsequent intergranular attack |
|
|
What are characteristics of Incoloy 825?
|
resistant to chloride SCC suffers crevice corrosion and pitting
uses: desalination plant components and heat exchangers exceptionally resistant to sulfuric and phosphoric acids and to seawater |
|
|
How can Monel 400 be hardened or strengthened?
|
coldwork or precipitation hardened
|
|
|
How can Inconel 625?
|
solid solution strengthening
|
|
|
How can Incoloy 825?
|
solid solution strengthening
|
|
|
What is the difference between cupronickels and monels?
|
Cupronickels aren't subject to erosion up to certain velocities
Monels are not Cupronickels are primarily Cu Monels are primarily Ni Both are unlimited SS |
|
|
How is zinc used to protect steel from rusting?
|
zinc coats steel surfaces by hot-dip galvanizing, electrode position, diffusion coating, metal spraying, and zinc-rich paints
due to the low corrosion rate of zinc, a coating of 0.003 in may provide protection for as long as 30 years in non-coastal environments not corrosion resistant in seawater zinc is anodic to most metals so a scratch or machined area will still be protected by the nature of the zinc anodic coating the zinc will be corroded in preference to the exposed steel |
|
|
What are the most important physical properties of Titanium and why?
|
low density (1/2 the density of steel)
high modulus of elasticity very high specific strength high melting point better mechanical properties can be better than those of many alloy steels |
|
|
Why isn't Ti considered a refractory metal when it has a high melting point?
|
it is not usually used for high-temperature applications
|
|
|
How is Ti-6Al-4V solution treated to form an unstable but long-lived higher strength beta phase?
|
at room temperature, Ti is crystal structure alpha-phase titanium
at 1620F (882C) BCC beta-phase titanium if quenched above its transformation temperature, high-strength martensite is formed if both phases-->precipitation hardening |
|
|
How is commercially pure titanium strengthened?
|
it is strengthened with elements such as carbon, oxygen, nitrogen, and hydrogen going into interstitial solid solution in it
|
|
|
What is the UNS # and primary alloys of Unalloyed Ti?
|
R50250
Ti |
|
|
What is the UNS # and primary alloys of Ti-6Al-4V?
|
R56400
Al, V and (<0.25% Fe) |
|
|
Why is Ti expensive (wrt corrosion resistance)?
|
excellent corrosion resistance to seawater and aqueous chloride solutions over a wide range of temperatures and concentrations
resistant to a wide range of oxidizing media such as nitric acid resistant to mildly reducing acids non-toxic and so it can be used to handle foods |
|
|
What properties make Ti a useful material?
|
strength
corrosion resistance high melting point |
