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2001 solved problems in esas Flipbook PDF
2001 solved problems in esas
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EFFECTS OF ALLOYING ELEMENTS ON STEEL
Element & Symbol Aluminum(Al)
Chromium(Cr)
Cobalt(Co)
Manganese (Mn)
Molybdenum (Mo)
Solid solubility In gamma Fe
In alpha Fe
1.1% (increase by carbon) 12.8% (in 0.5%C steels 20%)
36%±
Unlimited
75%
Unlimited
3% (with 0.5% C steels 8%)
Unlimited
3%
37.5% (less with lowered temp)
Influence upon ferrite Hardens considerably by solid solution Hardens slightly; increased corrosion resistance Hardens considerably by solid solution Hardens, ductility somewhat reduced
Age-hardening system in high Mo-Fe alloys.
Influence upon austenite (hardenenability) If dissolved in austenite increases hardenability mildly Increases hardenability moderately, similar to manganese Decreases hardenability as dissolved Similar to Ni
Increases hardenability strongly
Influence exerted through carbide. CarbideAction forming during tendency temperature Graphitizes —
Greater than Mn less than W
Mildly resists softening
Similar to Fe
Sustains hardness by solid solutions Very little in usual percentage
Greater than Fe, less than Cr
Strong, greater than Cr
Opposes softening by secondary hardening
Principal function of the element.
a. b. c. a. b. c. d. a. b. a.
c.
Counteracts effect of brittleness from sulphur. Increases hardenability inexpensively. High Mn. high C produces steels resistant to wear and abrasion. Raises grain coarsening temperature of austenite. Increases depth of hardening. Raises hot and creep strength promotes red hardness. Enhances corrosion resistance in stainless steels. Forms abrasion resistant particles. Strengthens unquenched or annealed steels. Toughens pearlitic-ferritic steels (especially low temperatures). Renders high Cr/Fe alloys austenitic.
a. b. c.
Strengthens low C steels. Increases resistance to atmospheric corrosion. Improves machinability in free cutting steel
b. c. a. b. c. d.
Nickel (N)
Phosphorous (P)
Unlimited
0.5%
10% independent of C content
2.8% independent of C content
Strengthens and toughens by solid solution
Hardens strongly by solid solution. Lowers ductility inducing Brittleness.
Increases hardenability slightly, austenite retention with higher carbon Increases hardenability similar to Mn
Graphitizes less than Fe
Nil
Very little in small percentages
—
Used as deoxidizer. Restricts grain growth. Alloying element in nitriding steels. Increases corrosion and oxidation resistance. Increases hardenabability. Increases strength at high temperature. With high C resists wear and abrasion. Contributes to red hardness by hardening ferrite. Alloying element is certain high-speed steels.
e. a. b.
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EFFECTS OF ALLOYING ELEMENTS ON STEEL
Element & Symbol
Solid solubility In gamma Fe
In alpha Fe
Influence upon ferrite
Influence upon austenite (hardenenability).
Influence exerted through carbide. CarbideAction forming during tendency temperature Negative Sustains graphitizes hardness by solid solution
Silicon (Si)
Approx. 2% (with 0.35% C approx 9%)
18.5% (carbon has little effect)
Hardens with loss in ductility.
Increases hardenability more than Ni
Titanium (Ti)
0.75% (with 0.2% C steels approx 1%)
Approx. 0.6% (less with lowered temperatures)
Gives age-hardening in high Fe-Ti alloy.
Probably increases hardenability very strongly dissolved; its carbide effects reduce hardenability
Greatest known (2% Ti renders, 0.5% C steel unhardenable)
Some secondary hardening
Tungsten (W)
6% (with 0.25% C 11%)
33% (less with lowered temperature)
Age-hardening system in W-Fe alloys.
Strong
Vanadium (V)
Approx. 1% (with 0.2% C steels 4%)
Unlimited
Hardens moderately in solid solutions.
Increases hardenability strongly in small quantities Increases hardenability very strongly as dissolved
Opposes softening by secondary hardening Maximum for secondary hardening
Very strong
Principal function of the element.
a. b.
Used as deoxidizer. Alloy for electrical and magnetic sheet metals. c. Improves oxidation resistance. d. Strengthens low alloy steels. a Fixes carbon in inert particles. b Reduces martensitic hardness and ardenability in medium Cr steels. c. Prevents formation of austenite in high Cr steels. d. Prevents localized depletion of Cr in stainless steels during long heating periods. a. Forms hard, abrasion resistant particles in tool steels, high-speed steels. b. Promotes red hardness and hot strength a. b. c.
Promotes fine grain-elevates coarsening temperature of austenite. Increases hardenability when dissolved. Resists tempering and causes marked secondary hardening.
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