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Coined by the U.S. SAE iron and steel committee in 1919, replacing the earlier designation 52-95; being a 52-series iron alloy (steel).
Etymology from Wiktionary, CC BY-SA 4.0.
52100
Today it means: A common ball bearing metal, also used for blademaking, knifemaking. A high-carbon low-alloy chromium steel; typically containing 1.0% carbon and 1.5% chromium, with low silicon (0.25%) and manganese (0.35%). Full definition →