| 摘要 |
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<=<=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; *+3V*>=0,4%, where Tr=1,8+1,1Mn+0,7Ni+0,6Cr+1,6*+0,5; Dr=540,25+24,5(Mo*+3V*)0,30+1,58Mn+0,74Ni+1,8Si+12,5(Cr)0,20; U=1600C+100(0,25Cr+*+4,5V*); R=3,8+10Si+3,3Mn+2,4Ni+1,4(Cr+Mo*); *=+W/2; V*=V+Nb/2+Ta/4; >=1/31+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 |
