| 摘要 |
Low alloy steel comprises by weight 0.17-0.27% carbon, 0.002-0.015% boron, 0.005-0.2% aluminium and up to 0.5% silicon, 2% manganese, 2% nickel, and 3% chromium, also molybdenum, tungsten, vanadium, niobium and tantalum wherein Mo+W/2 = 0-1.5% and V+Nb/2+Ta/4 = 0-0.5%. The proportions are also governed by the following equations: L=Cr+3 (Mo+W/2)+10 (V+Nb/2+Ta/4) omega 2.1; R=3.8 C+10 Si+3.3 Mn+2.4 Ni+1.4 (Cr+Mo+W/2)11;Tr=3.8 C+1.1 Mn+0.7 Ni+0.6 Cr+1.6 (Mo+W/2)+0.6 omega 3; and (Mo+W/2) is more than 0.7% if Cr does not exceed 1.5%. Also claimed are the use of the steel to make, preferably by casting, a mould for injection moulding of plastics and a wire made of the steel for welding or making welding electrodes.
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