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US 4,060,431 AGranted
Heat-treatable steel
AssigneeThyssen Edelstahlwerke AG
InventorsHelmut Brandis, Albert Von Den Steinen, Serosh Engineer
Life of this patent
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Abstract
Parts made of a heat-treated alloy steel having a minimum tensile strength of 700 N/mm.sup.2 and a notch toughness of at least 55 joules, wherein the alloy steel is a Mn/Cr/Nb alloy steel of lower alloy content than has hitherto been used to provide the desired strength/toughness properties.
Claims2
A part made of an alloy steel consisting essentially of
- 0.35% to 0.6% C
- 0.1% to 0.5% Si
- 0.3% to 1.0% Mn
- 0.1% to 0.6% Cr, and
- 0.01% to 0.1% Nb
- balance iron
- which after austenisation is rapidly cooled from temperatures above 1000.degree. C. to form a structure consisting principally of martensite and intermediate stage and then reheated to below the A.sub.1 critical temperature, whereby the said part retains its hardness, and has a minimum tensile strength of 700 N/mm.sup.2 and a notch toughness (DVM test) of at least 55 joules.
4 more elements
Dependencies are inferred from the claim text.