METHOD OF ENHANCING WEAR RESISTANCE OF DIES MADE FROM NITRIDED STEELS Russian patent published in 2000 - IPC

FIELD: methods of enhancing wear resistance of dies. SUBSTANCE: method of enhancing wear resistance of die provided with fermale die and circular punch includes preliminary determination of required depth of diffusion layer taking into account change of size of parts in the course of nitriding depending on tolerance for these parts separately for fermale die and punch and microhardness; then ion nitriding is performed in nitrogen-hydrogen plasma at temperature of 500 to 600 C for 2.66 to 8 hours at content of nitrogen in plasma of from 30 to 75%, provided the following conditions of nitriding are strictly observed as determined by quantities: H_μ = a₀+a₁•T+a₂•τ+a₃•N+a₂₃•τ•N+a₁₁•T², h_dl = b₀+b₁•T+b₂•τ+b₂₂•τ², where H_μ - is microhardness, Mpa; h_dl is depth of diffusion layer, mkm; T is nitriding temperature, C; τ is duration of nitriding, H; N is amount of nitrogen in nitrogen-hydrogen plasma, %; a_o= 11819.9; a₁=-37.1706; a₂=-95.3451; a₃=-6.48075; a₂₃=1.76565; a₁₁=0.03164; b_o=-81,571; b₁=1.63475; b₂=68.1865; b₂₂= -4.222492 are constant coefficients. EFFECT: increased durability of die and reduced labor consumption of strengthening technology. 2 tbl, 1 ex