STEEL BLANK FOR MANUFACTURE OF MOLD FOR PRESSURE MOLDING OR FOR MANUFACTURE OF PARTS SUBJECTED TO METALWORKING Russian patent published in 2007 - IPC C22C38/44 C22C38/46 C22C38/58 C21D9/22 

FIELD: manufacture of molds or parts subjected to metalworking.

SUBSTANCE: thickness of blank exceeds 20 mm; blank has martensite or martensite-bainite structure, hardness in all points is from 430 to 530 HB; composition of steel from which the blank is made contains the following components, mass-%: 0,180≤С≤0,400, Si≤0,8, Mn≤2,5, Ni≤3, Cr≤3,5, Mo+W/2≤2,8, V+Nb/2+Ta/4≤0,5, Al≤0,4, Ti+Zr/2≤0,1, 0,0005%<B<0,015%; S+Se+Te≤0,2; Pb+Bi<0,2; Ca≤0,1; the remainder being iron and admixtures entrapped in the course of process. Chemical composition satisfies the following ratios: 3,2≤Tr≤9; 85<Dr≤95; U/Dr≤10,0; Мо*+3×V*≥0,4%, where Tr=1,8×С+1,1×Mn+0,7×Ni+0,6×Cr+1,6×Мо*+0,5; Dr=54×С^0,25+24,5×(Mo*+3×V*)^0,30+1,58×Mn+0,74×Ni+1,8×Si+12,5×(Cr)^0,20; U=1600×C+100×(0,25×Cr+Мо*+4,5×V*); R=3,8×С+10×Si+3,3×Mn+2,4×Ni+1,4×(Cr+Mo*); Мо*=Мо+W/2; V*=V+Nb/2+Ta/4; В≥1/3×К1+0,5, where K1=Min(I*; J*); I*=Max(0; 1) and J*=Max(0;J); I=Min(N; N-0.29(Ti+Zr/2-5).

EFFECT: increased hardness; avoidance of cracking.

17 cl, 2 tbl