HD die steel is a kind of steel developed by China on the basis of UHBQR080 steel. HD die steel does not contain cobalt, and adds 1% nickel and trace niobium and boron. Its high temperature toughness, high temperature hardness, and thermal stability , Thermal fatigue resistance, etc. are all better. The surface heating temperature of this type of mold can reach 710°C. The limitation of HD steel supply restricts the promotion and application of HD2 new steel grade. Under the same hardness. The fracture toughness of HD steel is 50% higher than that of 3Cr2W8V steel. The tensile strength at 700℃ is increased by 70%, and the thermal fatigue resistance and thermal wear resistance are doubled and 50% respectively. C0.35%-0.45%, Si≤0.35%, Mn≤0.40%, Cr2.50%-3.00%, Mo1.80%-2.20%, Ni0.80%-1.20%, V1.00%-1.40%, Nb0.10%-0.25%, S≤0.30%, P≤0.30% Heat treatment process specification Critical point temperature: Ac1=770℃, Ms=320℃ Thermal processing specification: heating temperature 1100-1150℃, starting temperature 1000-1050℃ , Termination temperature ≥850℃, sand cooling after forging. Annealing specification: 840-860℃ 4h annealing, after the furnace is cooled to 550℃, it is air-cooled and the annealing hardness is 190-220HBW. Common quenching and tempering specifications: quenching temperature 1130±10℃, oil or air cooling, tempering temperature 590±10℃. Ion nitriding specification: 3h ion nitriding at 540℃, NH3 flow rate is 500L/h, furnace pressure is 530-580MPa. The thickness of the compound layer is 19um, the depth of the diffusion layer is 0.252mm, and the surface hardness is 1050-1100HV. In order to obtain the tough nitriding layer, the ammonia gas is diluted by adding argon gas. When the volume fraction of NH3 is 10%, a pure diffusion layer without white bright layer can be obtained. Ion nitrocarburizing specification 540℃3h ion nitrocarburizing, NH3: CH3COCH3=8:1, compound layer 12um, diffusion layer 0.192mm, surface hardness 900-1000HV. Ionic sulfur-nitrogen co-infiltration specification: 540 ℃ 2.5h ion sulfur-nitrogen carbon co-infiltration, the steam flow of NH3+CH3COCH3+CS2 mixture should be controlled at about 20:1. The sulfide layer is 8.2um, the compound layer is 1.82um., and the diffusion layer is 0.21mm. 1. The application of this steel in hot extrusion punches: the working conditions for hot extrusion of large-caliber elastomer blanks are high temperature, high pressure, and cold The heat is alternated, and as a hot extrusion punch, its material requirements are very demanding. It replaces the traditional hot work die steel 3Cr2W8V that has been used for a long time.
2. It is suitable for black and non-ferrous metal hot extrusion dies with higher heating temperature. The service life is more than twice that of 3Cr2W8V steel.
3. Suitable for making hot extrusion and precision forging dies for ferrous and non-ferrous metals.
4. Suitable for all kinds of hot work molds that work at around 700℃
5. The service life of crank hot forging die is 4700-8900 pieces, which is 2-3 times higher than that of 3Cr2W8V steel forging die.
6. HD steel is used in hot extrusion punches for steel pipes, copper alloy pipe extrusion bottom molds and perforation pins, as well as hot extrusion bearing punches and concave molds, valve extrusion low molds and other molds. The service life is longer than 3Cr2W8V. Steel length.
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