AISI 4140 Steel
AISI 4140 Steel
This is one of the chromium, molybdenum, manganese low alloy steels noted for toughness, good torsional strength and good fatigue strength.
This alloy is hardened by heating to 1550 F and quenching in oil. It is best to normalize the alloy by heating at 1675 F for a long enough time to permit thorough heating, followed by air cooling, prior to the hardening treatment.
Most commonly used at rc 28-36 with the highest strength coming at rc 40-45.
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Carbon
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0.38 - 0.43
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Chromium
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0.8 - 1.1
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Iron
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Balance
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Manganese
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0.75 - 1
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Molybdenum
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0.15 - 0.25
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Phosphorus
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0.035 max
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Silicon
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0.15 - 0.35
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Sulphur
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0.04 max
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