Entc 207 Test 3 Review

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  • Topic: Stainless steel, Steel, Iron
  • Pages : 4 (855 words )
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  • Published : February 28, 2013
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Stainless Steels: must have at least 10% chromium
A. Ferritic Stainless Steels: Iron, chromium + low carbon a. Magnetic
b. Lowest cost
c. Non-hardenable
i. Can be annealed
d. BCC structure
e. Low carbon
ii. Less than .2%
f. Chromium content
iii. 16-20%
B. Martensitic Stainless Steel: iron, chromium + higher carbon h. Magnetic
i. Martensitic Structure
j. Hardenable
k. High Carbon
iv. Up to 1.2%
l. Chromium
v. 12-18%
m. Poor Weldability and notch sensitivity
n. Used for applications with corrosion resistance and wear resistance C. Austinitic Stainless Steel: iron, chromium, nickel + low carbon o. All 3xx are austenitic and are nickel chromium alloys p. Non-Magnetic unless cold worked

q. Non-Hardenable
vi. Can be annealed and stress relieved
r. Very low Carbon Content
s. Chromium
vii. 16-26%
t. Nickel
viii. 8-24%
u. Can be hardened by cold working
v. 304 is the most widely used stainless steel in industry Physical and Mechanical Properties
* Density
* About the same as carbon steel
* Conductivity
* Poor conductors of both heat and electricity
* Thermal conductivity of stainless is about half of carbon steel * Electrical resistivity of stainless steel can be as much as 6 times as much as carbon * Expansion
* Austenitic (300 series): coefficient of thermal expansion is up to 50% greater than carbon steel * Modulus of elasticity
* Slightly lower than carbon steel
* Stainless Modulus: 28-29*10^6 psi
* Carbon Steel: 30*10^6 psi
* Mechanical Properties
* 304 and 316: Better tensile, ductility, and toughness than mild steel * 420 and 440C: high hardness; used as tool steels
* 310 or 446: best for scaling resistance
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