1) characteristics of hardened steel alloy tool steel, good carburizing heat treatment process and the performance of the steel at ≤960 ℃ fine grain structure, commonly used in long-term heating carburizing temperature, the grain grew no tendency little residual austenite after quenching, therefore, the steel has high strength and wear resistance, excellent cutting performance, the main performance and 20CrMnTi and 20CrNi steel similar. Tensile strength σ ≥1080MPa, yield strength σ ≥885MPa, elongation δ ≥10%, 45% reduction of swelling, impact toughness (impact toughness) α ≥69J / cm, hardness ≤207HB, blank sample size to 15mm.
(2) the delivery status normalizing, annealing, tempering or heat treatment.
(3) the chemical composition of the standard GB / T 3077-1988 Steel (best quality scores,%) C 0.17 ~ 0.23, Si 0.17 ~ 0.37, Mn O.80 ~ 1.10, P O.013, S O.013, Cr l.00 ~ 1.30, Ti O.04 ~ 0.10, Cu O. 09.
(4) under the steel processing route forging die blanks feed → → → annealing cold extrusion machinery roughing → → recrystallization Mechanical finishing crystal annealing → → → carburizing quenching and tempering → polishing → assembly.
(5) quenching and tempering specification quenching temperature 860 ℃ ± 10 ℃, oil cooling, tempering temperature of 200 ℃, water or air cooling. Tempered martensite microstructure.
(6) Typical application examples
① The steel extruded aluminum sleeve cold extrusion die, D16, D20-type wire rope pressed aluminum sleeve cold extrusion die, the original use of CrWMn steel quenching, tempering, hardness 45 ~ 50HRC, despite the hardness of the more cold extrusion die low, but because CrWMn carbide steel tissue inhomogeneity could easily lead to mold chipping, cracking and early failure, life instrument for more than 1,000 pieces, some only a few hundred pieces.
Elected by 20CrMnTi steel production of these two sets of aluminum extrusion die of cold, after 950 ℃ heated salt water quenching, tempering is not used directly, mold hardness 46 ~ 48HRC, extruded aluminum cover over 2000 pieces, still in use.
② There are also many examples of the application of low-carbon martensitic steel strong cold die quenching process manufacturing.