Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of high rigidity height polishing pre-hardening plastic mould steel.
For solving the problems of the technologies described above, the concrete technical scheme that high rigidity height polishing pre-hardening plastic mould steel of the present invention adopts is:
A kind of high rigidity height polishing pre-hardening plastic mould steel, its innovative point is: in the chemical composition of described plastic mould steel, the mass percent of each main alloy element is:
C 0.25~0.40%, Si 0.10~0.30%,
Mn 1.50~2.00%, Cr 1.50~2.50%,
Mo 0.50~1.00%, V 0.10~0.30%,
Ni 0.60~1.50%, Nb ≤0.15%,
P ≤0.025%, S ≤0.005%
Fe surplus.
On this basis, the mass percent of each main alloy element in described plastic mould steel is:
C 0.26%, Si 0.20%, Mn 1.70%, Cr 1.8%,
Mo 0.60%, V 0.20%, Ni 1.0%, P≤0.015%, S≤0.002%, Nb 0.06%, Fe surplus.
Another technical problem that the present invention will solve is to provide a kind of method of producing this high rigidity height polishing pre-hardening plastic mould steel.
For solving the problems of the technologies described above, the concrete technical scheme that the preparation technology of high rigidity height polishing pre-hardening plastic mould steel of the present invention takes is as follows:
A preparation technology for high rigidity height polishing pre-hardening plastic mould steel, its innovative point is: described preparation technology has following steps:
A. smelt: undertaken preparing burden by the chemical composition of high rigidity height polishing pre-hardening plastic mould steel and mass percent, electric arc furnace smelting and refining, then carry out vacuum outgas and casting, then heat send forge furnace;
B. High temperature diffusion thermal treatment: Heating temperature is 1100 ~ 1200 DEG C, soaking time is 15 ~ 20h;
C. forge hot-work: 900 ~ 1200 DEG C will be cooled to through the heat treated steel ingot of High temperature diffusion, in this temperature range, carry out multiway forging processing, adopt two upsettings two to pull out forging mode, always forge compression ratio >=3, final forging temperature >=850 DEG C;
D. heat treatment after forging: air cooling after forging, then fill normalizing furnace normalizing treatment, Heating temperature 880 ~ 950 DEG C, is incubated 10 ~ 15 hours, below the air cooling to 200 DEG C of coming out of the stove, advance and retreat stove;
E. hydrogen annealing is expanded: 600 ~ 700 DEG C of temperature range inside holding 40 ~ 50 hours, stove was chilled to less than 200 DEG C and comes out of the stove;
F. Pre-hardening treatment: be heated to 850 ~ 950 DEG C insulation 20 ~ 30 hours, water-cooled of coming out of the stove or mist cold or air-cooled to surface temperature less than 200 DEG C, enter tempering stove;
G. tempering heat treatment: be heated to 500 ~ 600 DEG C, insulation 20-40 hour, stove is chilled to less than 250 DEG C, air cooling of coming out of the stove.
On this basis, in described High temperature diffusion heat treatment step, heat up and adopt stepped heating mode.
Beneficial effect of the present invention: high rigidity height polishing pre-hardening plastic mould steel of the present invention improves the content of Mo and adds microalloy element Nb.Due to the Mo element of high level, and there is higher hardening capacity and hardenability.Adding of microalloy Nb can the effectively crystal grain of refinement steel and homogeneity of ingredients, makes prevulcanized steel have higher uniformity of hardness, thus obtains higher polishing performance.
In conjunction with above feature, compared with H11, steel grade of the present invention has higher polishing performance and lower cost of alloy, this be China's manufacturing industry especially automobile industry bring huge contribution, and improve China's die steel manufacture level and the market competitiveness.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, the following specific embodiment of the present invention is described further technical scheme of the present invention, but the invention is not restricted to following specific embodiment.
embodiment 1
In the present embodiment, moiety and the mass percent thereof of the employing of high rigidity height polishing pre-hardening plastic mould steel are as follows:
C 0.40%, Si 0.30%, Mn 2.00%, Cr 2.50%,
Mo 1.00%, V 0.30%, P 0.025%, S 0.005%,
Ni 1.5%, Nb 0.15%, Fe surplus.
Adopt the material in this embodiment to carry out the technological process of production high rigidity height polishing pre-hardening plastic mould steel and step as follows:
1. smelt: prepare burden by the alloying element proportioning in embodiment, batching is sent to electric arc furnace to carry out smelting and refining, then adopt vacuum outgas to remove dissolved gases in liquid metal, prevent defect, finally be cast into steel ingot, then heat send forge furnace; Heat is adopted to send exactly in order to reach the object of energy-saving and emission-reduction.
2. High temperature diffusion thermal treatment: steel ingot classification in forge furnace is heated up, namely 1100 ~ 1200 DEG C are finally heated at 600 DEG C, 800 DEG C, 1100 DEG C isothermals respectively, insulation 15 ~ 20h, soly can guarantee that steel ingot internal and external temperature is even, in order to enable steel ingot eliminate dendritic segregation as much as possible, soaking time is 20h.
3. forge hot-work: 900 ~ 1200 DEG C will be cooled to through the heat treated steel ingot of High temperature diffusion, in this temperature range, carry out multiway forging processing, and adopt two upsettings two to pull out forging mode, always forge compression ratio >=3, final forging temperature >=850 DEG C;
4. heat treatment after forging: air cooling after forging, then fills normalizing furnace and carries out normalizing treatment, Heating temperature 880 ~ 950 DEG C, be incubated 10 ~ 15 hours by steel ingot, below the air cooling to 200 DEG C of coming out of the stove, and advance and retreat stove; In order to make complete austenitizing in steel ingot, obtaining good mechanical property, Heating temperature being selected 930 DEG C, and soaking time is 15h.
5. expand hydrogen annealing: 600 ~ 700 DEG C of insulations 40 ~ 50 hours, stove was chilled to less than 200 DEG C and comes out of the stove; In order to make the hydrogen be solid-solution in steel spread elimination completely, avoid occurring white point class hydrogen embrittlement in tissue, the soaking time in this step selects 50 hours.
6. Pre-hardening treatment: be heated to 850 ~ 950 DEG C insulation 20 ~ 30 hours, water-cooled of coming out of the stove or mist cold or air-cooled to surface temperature less than 200 DEG C, enter tempering stove; In order to make, in this step, steel is quenched to martensite, select soaking time to be 30 hours, meanwhile, comparatively large by steel ingot internal stress after water-cooled, easy strain cracking, during air cooling, speed of cooling is comparatively slow, so this step selects mist cold.
7. tempering heat treatment: be heated to 500 ~ 600 DEG C, be incubated 20 ~ 40 hours, stove is chilled to less than 250 DEG C, to come out of the stove air cooling, in order to the sufficient tempering of steel ingot can be made, produce tempered sorbite, eliminate internal stress, prevent workpiece deformation or cracking, in this step, soaking time selects 30 hours.
High rigidity height polishing pre-hardening plastic mould steel in the present embodiment is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (the wide * of long * is thick) 2500mm*1300mm*500mm module, and performance test is carried out in sampling, and test result is:
A phase-change characteristic:
The CCT curve of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 1.
B tempering characteristics:
High rigidity height polishing pre-hardening plastic mould steel belt roof bolt rational curve of the present invention as shown in Figure 2.
C microstructure:
The microstructure of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 3.
embodiment 2
In the present embodiment, moiety and the mass percent thereof of the employing of high rigidity height polishing pre-hardening plastic mould steel are as follows:
C 0.26%, Si 0.20%, Mn 1.7%, Cr 1.8%,
Mo 0.60%, V 0.20%, P 0.015%, S 0.002%,
Ni 1.00%, Nb 0.06%, Fe surplus.
The technological process that material in employing above-described embodiment carrys out production high rigidity height polishing pre-hardening plastic mould steel is identical with embodiment 1 with step, does not repeat them here.
The present embodiment high rigidity height polishing pre-hardening plastic mould steel is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (the wide * of long * is thick) 2500mm*1300mm*500mm module, and performance test is carried out in sampling, and test result is:
A phase-change characteristic:
The CCT curve of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 4.
B tempering characteristics:
High rigidity height polishing pre-hardening plastic mould steel belt roof bolt rational curve of the present invention as shown in Figure 5.
C microstructure:
The microstructure of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 6.
embodiment 3
in the present embodiment, moiety and the mass percent thereof of the employing of high rigidity height polishing pre-hardening plastic mould steel are as follows:
C 0.25%, Si 0.10%, Mn 1.50%, Cr 1.50%,
Mo 0.50%, V 0.10%, P 0.005%, S 0.001%,
Ni 0.60%, Nb 0.001%, Fe surplus.
Adopt the material in this embodiment to come the technological process of production high rigidity height polishing pre-hardening plastic mould steel and step as described in example 1 above, do not repeat them here.
High rigidity height polishing pre-hardening plastic mould steel of the present invention is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (the wide * of long * is thick) 2500mm*1300mm*500mm module, and performance test is carried out in sampling, and test result is:
A phase-change characteristic:
The CCT curve of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 7.
B tempering characteristics:
High rigidity height polishing pre-hardening plastic mould steel belt roof bolt rational curve of the present invention as shown in Figure 8.
C microstructure:
The microstructure of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 9.
comparative example
h11 steel moiety and mass percent as follows:
C 0.38, Si 1.00, Mn 0.40, Cr 5.20, Mo 1.30, V 0.40, P 0.025, S 0.003, Fe surplus.
Prepared by employing ordinary method, final finished specification is (the wide * of long * is thick) 2500mm*1300mm*500mm module, and performance test is carried out in sampling, and test result is:
A phase-change characteristic:
The CCT curve of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 10.
B tempering characteristics:
High rigidity height polishing pre-hardening plastic mould steel belt roof bolt rational curve of the present invention as shown in Figure 11.
C microstructure:
The microstructure of high rigidity height polishing pre-hardening plastic mould steel of the present invention as shown in Figure 12.