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Building Design and Construction Handbook - Merritt - Ventech!

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TABLE 4.19 Effects of Alloying Elements in Steel* (Continued)<br />

Element<br />

In gamma<br />

iron<br />

Solid solubility<br />

In alpha<br />

iron<br />

Phosphorus (P) 0.5% 2.8%<br />

(irrespective<br />

of carbon<br />

content)<br />

Silicon (Si) 2% � (9%<br />

with<br />

0.35% C)<br />

18.5% (not<br />

much<br />

changed by<br />

carbon)<br />

Influence on<br />

ferrite<br />

Hardens strongly<br />

by solid<br />

solution<br />

Hardens with loss<br />

in plasticity<br />

(Mn � Si � P)<br />

Influence on<br />

austenite<br />

(hardenability)<br />

Increases<br />

hardenability<br />

Increases<br />

hardenability<br />

moderately<br />

Influence exerted through<br />

carbide<br />

Carbideforming<br />

tendency<br />

Action<br />

during<br />

tempering Principal functions<br />

Nil 1. Strengthens lowcarbon<br />

steel<br />

2. Increases resistance<br />

to corrosion<br />

3. Improves<br />

machinability in<br />

free-cutting steels<br />

Negative<br />

(graphitizes)<br />

Sustains<br />

hardness<br />

by solid<br />

solution<br />

1. Used as generalpurpose<br />

deoxidizer<br />

2. Alloying element<br />

for electrical <strong>and</strong><br />

magnetic sheet<br />

3. Improves oxidation<br />

resistance<br />

4. Increases<br />

hardenability of<br />

steel carrying<br />

nongraphitizing<br />

elements<br />

5. Strengthens lowalloy<br />

steels

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