STEEL SUITABLE FOR PLASTICS MOULDING TOOLS Russian patent published in 2021 - IPC C22C38/44 C22C38/48 C22C38/50 C22C38/54 C22C33/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular to steel used for producing plastics moulding tools, in particular for producing compression moulds. The steel comprises, in wt%: C: 0,02-0,04, Si: 0,1-0,4, Mn: 0,1-0,5, Cr: 11-13, Ni: 7-10, Cr+Ni: 19-23, Mo: 1-25, Al: 1,4-2,0, N: 0,01-0,75, if necessary, at least one of: Cu: 0,05-2,5, B: 0,002-2,0, S: 0,01-0,25, Nb: ≤0,01, Ti: ≤2, Zr: ≤2, Ta: ≤2, Hf: ≤2, Y: ≤2, Ca: 0,0003-0,009, Mg: ≤0,01, O: 0,003-0,80 and РЗМ: ≤0,2, the rest being Fe and impurities. The steel microstructure satisfies at least one of the following requirements: the matrix contains ≥75 vol.% of martensite, the size of all AlN particles equals to ≤ 4 μm.

EFFECT: steel has high strength and fracture toughness as well as high purity, good polishing and homogeneous properties, including in large size.

10 cl, 1 tbl, 3 ex