| 摘要 |
<p>The invention relates to a bulk steel for the production of injection moulds for plastic material or for the production of tools for working metals with a thickness greater than 20 mm, the structure of which is entirely martensitic or martensite-bainitic, the hardness of which at all points lies between 370 HB and 450 HB and the chemical composition of which is as follows in wt. %: 0.12 % = C = 0.32 %; Si = 0.8 %; Mn = 2.5 %; Ni = 3 %; Cr = 3.5 %; Mo+W/2 = 2.2 %; 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 impurities arising in production. The chemical composition further satisfies the following relationships: 3.2 = Tr = 6.5; 77 = Dr = 85; U = 850; in which with content expressed in wt. %, Tr = 1.8xC + 1.1xMn +0.7xNi + 0.6xCr + 1.6xMo* + 0.5; Dr = 54xC0.25 + 24.5x(Mo* + 3xV*)0.30 + 1.58xMn + 0.74xNi + 1.8xSi + 12.5x(Cr)0.20; U = 1600xC + 100x(0.25xCr + Mo* + 4.5xV*); R = 3.8xC + 10xSi + 3.3xMn + 2.4xNi + 1.4x(Cr + Mo*); Mo* = Mo + W/2; V* = V + Nb/2 + Ta/4; the content of Al, Ti, Zr, N and B being such that: B = 1/3 x K1 + 0.5; with K1 = Min (I*; J*), I* = Max (O; I); J= Max (O; J); I = Min (N; N-0.29 (Ti + Zr/2 - 5)); formula (a).</p> |
