Cold work tool steel with outstanding weldability
AssigneeRovalma, S.A.
InventorIsaac Valls
Life of this patent
Estimating the term…
Abstract
A cold work tool steel with average or above wear resistance, a hardness in excess of (60) HRc and a very good toughness but with considerably lower carbon contents leading to highly improved weldability is obtained by combining the presence of primary carbides (or alternatively nitrides and/or borides) with other strengthening mechanisms like precipitation hardening or even solid solution. Vanadium rich MC type carbides, modified with refractory metal additions, present the best compromise of hardness and fracture toughness for several applications, while for other applications harder carbides, such as Ti carbides or Ti mixed carbides (primarily with V, Mo and/or W) will be the preferred ones, alternatively using Zr and Hf mixed carbides.
Claims24
An at least partly martensitic cold work tool steel having the following composition, all percentages being in weight percent:
- % Ceq = 0.25-2.5
- % C = 0.25-2.5
- % N = 0-2%
- B = 0-2
- % Cr = 0.1-10
- % Ni = 3-12
- % Si = 0.01-2
- % Mn = 0.08-3
- % Al = 0.5-5
- % Mo = 0-10
- % W = 0-15
- % Ti = 0-3
- % Ta = 0-2
- % Zr = 0-2
- % Hf = 0-2,
- % V = 0-12
- % Nb = 0-2
- % Cu = 0-4
- % Co = 0-8,
- % S = 0-1%
- Se = 0-1
- % Te = 0-1
- % Bi = 0-1
- % As = 0-1
- % Sb = 0-1
- % Ca = 0-1,
- the rest consisting of iron and unavoidable impurities, wherein
- % Ceq=% C+0.86*% N+1.2*% B,
- characterized in that
- % Cr+% V+% Mo+% W>3 and
- % Al+% Mo+% Ti>1.5,
- with the proviso that
- when % Ceq=0.45-2.5, then % V=0.6-12;
- or
- when % Ceq=0.25-0.45, then % V=0.85-4;
- or
- when % Ceq=0.25-0.45, then % Ti+% Hf+% Zr+% Ta=0.1-4.
Dependencies are inferred from the claim text.