Steel alloy plastic moulding tool and tough-hardened blank for plastic moulding tools
A steel alloy has a chemical composition which contains in weight-%, 0.16-0.27 C, 0.06-0.13 N, wherein total content of C+N shall satisfy the condition, 0.3<C+N<0.4, 0.1-1.5 Si, 0.1-1.2 Mn, 12.5-14.5 Cr, 0.5-1.7 Ni, 0.2-0.8 Mo, 0.1-0.5 V. The steel is suitable for plastic molding tools.
1. Steel alloy for plastic molding tools, having a chemical composition consisting essentially of in weight-%,
0.16-0.27 C
0.06-0.13 N, wherein the total content of C+N shall satisfy the condition
0.3≦C+N≦0.4
0.1-1.5 Si
0.1-1.2 Mn
12.5-14.5 Cr
0.5-1.7 Ni
0.2-0.8 Mo
0.1-0.5 V
optionally one or more of the elements S, Ca and O for the improvement of the cutability of the steel, in amounts up to
max. 0.15% S
max. 0.1% (100 ppm) Ca
max. 0.01% (100 ppm) O,
balance iron and unavoidable impurities.
2. Steel Alloy according to claim 1 , wherein it contains at least 0.20 %. C.
3. Steel Alloy according to claim 2 , wherein it contains max 0.25% C.
4. Steel alloy according to claim 1 , wherein it contains about 0.10% N.
5. Steel alloy according to claim 1 , wherein it contains max. 1.0% Si.
6. Steel alloy according to claim 5 wherein it contains max. 0.5% Si.
7. Steel alloy according to claim 1 , wherein it contains max. 1.0% Mn.
8. Steel alloy according to claim 7 , wherein it contains max. 0.8% Mn.
9. Steel alloy according to claim 8 , wherein it contains max. 0.3-0.8% Mn.
10. Steel alloy according to claim 1 , wherein it contains 13-14% Cr.
11. Steel alloy according to claim 1 , wherein it contains 1.0-1.5% Ni.
12. Steel alloy according to claim 1 , wherein it contains max. 0.6% Mo.
13. Steel alloy according to claim 12 , wherein it contains 0.3-0.4% Mo.
14. Steel alloy according to claim 1 , wherein it contains 0.25-0.40% V.
15. Steel alloy according to claim 1 , wherein it contains
0.22% C
0.10% N
0.3% Si
0.5% Mn
13.5% Cr
1.2% Ni
0.35% Mo
0.35% V.
16. Steel alloy according to claim 1 , wherein it contains 0.07-0.15% S but no intentionally added amount of calcium.
17. Steel alloy according to claim 1 , wherein it contains
0.025-0.15% S
3-75 ppm Ca, and
10-40 ppm O.
18. Steel alloy according to claim 17 , wherein it contains
0.025-0.15% S
5-40 ppm Ca, and
10-40 ppm O.
19. Steel alloy according to claim 1 , wherein said steel has been hardened from 1020° C. followed by tempering at 250° C., 2×2 h, such that the elements Or, Mo and N are in solid solution in the steel matrix and are not bound in the form of carbides, nitrides, and/or carbonitrides, and the steel has a PRE value which is at least 14.8, the PRE value being expressed through the formula:
PRE =% Cr( s )+3.3×% Mo( s )+20×% N( s ), were Cr( s ), Mo( s ) and N( s )
means Cr, Mo and N in solid solution in the matrix of the steel.
20. Steel alloy according to claim 19 , wherein the steel has a PRE value which is at least 15.0.
21. Plastic molding tool wherein it is made of a steel alloy according to claim 1 and wherein said steel, after hardening from 1020-1030° C. followed by tempering at either 200-250° C. or at 500-520° C., has a micro structure, the matrix of which consists substantially of tempered martensite and, in the matrix of the steel, 0.3-1.0 vol-% primary precipitated carbonitrides consisting essentially of M(C, N) carbonitrides.
22. Tough hardened blank in the form of a bar, rod, plate or block for plastic molding tools, wherein it is made of a steel alloy according to claim 1 , and wherein said steel, after heat treatment comprising austentizing at 1020-1030° C., followed by cooling to room temperature and tempering at 540-625° C., such that the steel matrix has a hardness of 35-45 HRC and a micro structure, the matrix of which consists substantially of tempered martensite and, in the matrix of the steel, 0.3-1.0 vol-% primary precipitated carbonitrides consisting essentially of M(C, N) carbonitrides.