Effect of Alloying Elements

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  • Topic: Steel, Carbon steel, Valve
  • Pages : 2 (265 words )
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  • Published : February 26, 2013
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Effect of Alloying Elements (Cr, Mn, Ni) on the Soundness of Low Carbon Steel Castings

Low Carbon Steel (LCS)

Low-carbon steels contain up to 0.30% C. The largest category of this class of steel is flat-rolled products (sheet or strip), usually in the cold-rolled and annealed condition. The carbon content for these high-formability steels is very low, less than 0.10% C, with up to 0.4% Mn. Typical uses are in automobile body panels, tin plate, and wire products.

ASTM A217 Gr WC9 alloy Steel Composition

Element requirement |C |Mn |Si |P |S |Cr |Ni |Mo |Cu |W | |Minimum |0.130 |0.50 |0.00 |0.000 |0.000 |2.00 |0.00 |0.90 |0.00 |0.00 | |Maximum |0.180 |0.70 |0.60 |0.020 |0.020 |2.50 |0.50 |1.20 |0.30 |0.10 | |Applications of WC9 alloy

Used in
• Casings of steam turbines, compressors, gas turbines. • Valves such as Globe Valve body and bonnet, Check Valve, Gate Valve. • Nozzles and chemical reactors.
• Service temperatures up to about 570 °C.

Gate Valve Body
Globe Valve Body

[pic]

Advantages:
• Easily Weldable with similar weld metal.
• Has higher resistance to Graphitization
• High Creep resistance.

Limitations:

• Applicable for valves operating in the Temperature range of -20 to 1100 °F. • Has limited Corrosion resistance.

Carbon Equivalent (CE):

CE= C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15

• CE%0.05% causes Edge Surface defects in Low Carbon Steels annealed at 700°C. • Ni in the range of 0.5-0.8% lowers the transformation temperature.
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