Summary of the invention
The object of the present invention is to provide a kind of low cost super-section Pre-Bainitic sclerosis plastic mould steel, there is higher hardening capacity and uniformity of hardness, be applicable to manufacture bumper mould and some large-scale household electrical appliances moulds.
For solving the problems of the technologies described above, the present invention adopts following technical scheme to realize: super-section Pre-Bainitic sclerosis plastic mould steel, its innovative point is: in the chemical composition of described steel, the mass percent of each alloying element is: C is 0.25~0.40%, Si is 0.10~0.30%, Mn is 2.00~3.00%, Cr is 1.00~2.00%, Mo is 0.10~0.30%, V is 0.10~0.30%, P < 0.03%, S < 0.03%, Ni is 0.10~0.30%, Nb≤0.15%, Fe surplus.
Preferably, in the chemical composition of described steel, the mass percent of each alloying element is: in the chemical composition of described steel, the mass percent of each alloying element is: C is that 0.28%, Si is that 0.20%, Mn is 2.30%, Cr is 1.30%, Mo is that 0.20%, V is 0.20%, P < 0.020%, S < 0.015%, Ni is that 0.20%, Nb is 0.08%, Fe surplus.
The present invention reduces the content of Mo on 718 basis, greatly reduce and even do not use Ni element, increase substantially the content of Mn element, thereby greatly reduce the cost of alloy of this steel, be that steel per ton reduces approximately 1000 yuan of cost of alloy, the nerf bar mould that is equivalent to 30 tons of pairs is saved cost of alloy more than approximately 30,000 yuan.
The preparation method who another object of the present invention is to provide a kind of super-section Pre-Bainitic sclerosis plastic mould steel, comprises smelting, High temperature diffusion thermal treatment, forges hot-work, forges rear pre-hardening processing and tempering heat treatment operation, and concrete steps are as follows:
(1) smelt: by the chemical composition of super above-mentioned large section Pre-Bainitic sclerosis plastic mould steel and weight percent for preparing burden, electric arc furnace smelting and refining, then carry out vacuum outgas and casting, then heat is sent forge furnace;
(2) High temperature diffusion thermal treatment: Heating temperature is 1150~1250 DEG C, soaking time is 15~20h;
(3) forge hot-work: will be cooled in 950~1200 DEG C of temperature ranges and carry out multiway forging processing through the heat treated steel ingot of High temperature diffusion, and adopt two upsettings two to pull out forging mode, and always forge compression ratio >=3, final forging temperature >=850 DEG C;
(4) forge after pre-hardening processing: after forging, adopt water-cooled or mist cold, cooling fast to be greater than the speed of 0.015 DEG C/s, drop to 200 DEG C to temperature and reinstall below fiery process furnace;
(5) tempering heat treatment: be heated to 450~600 DEG C, be incubated after 20~40 hours cooling rate≤30 DEG C/h and be chilled to below 250 DEG C, the air cooling of coming out of the stove.
Further, described High temperature diffusion thermal treatment, point stepped heating in steel ingot temperature-rise period, ensures that steel ingot internal and external temperature is even, respectively at 600 DEG C, 800 DEG C and 1100 DEG C of isothermals; After High temperature diffusion thermal treatment, at 950~1200 DEG C of temperature isothermals, after steel ingot temperature is even, carry out conducting forging processing.
Pre-hardening processing after described forging, adopts air-cooled after forging or mist is cold or water-cooled to 200 DEG C, temper immediately, temper 2 times, 450~600 DEG C of each tempering temperatures, each tempering insulation time 15~20h.
Steel grade of the present invention is not or contain lower Ni content, thereby do not have a white point problem, so saved long expansion hydrogen heat treatment step in manufacturing processed, greatly shorten the manufacturing cycle (shortening approximately 7 day time) so on the one hand, reduce on the other hand manufacturing cost (steel per ton reduce about 800-1000 unit).
In addition, steel grade of the present invention is due to the Mn element of high level, and there is higher hardening capacity, in manufacturing processed, do not need to adopt modified (quenching+tempering) treatment process to carry out pre-hardening as 718 or 1.2738 steel, but can utilize forging preheating, laggard sector-style is cold or mist is cold or the mode such as water-cooled reaches prevulcanized object forging.Therefore, this on the one hand shortens the manufacturing cycle (shortening approximately 6 day time), reduces on the other hand manufacturing cost (steel per ton reduce about 1200-1500 unit).
Beneficial effect of the present invention: compared with 718 or 1.2738 steel, steel grade of the present invention shortens about 13-15 days of manufacturing cycle, and steel per ton reduces the about 3000-3500 of manufacturing cost unit.This brings huge contribution for China's manufacturing industry especially automobile industry, and improves China's die steel manufacture level and the market competitiveness.
Brief description of the drawings
Fig. 1 is the super-section Pre-Bainitic hardening die steel CCT curve of embodiment 1.
Fig. 2 is the metallographic structure of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 1.
Fig. 3 is that the super-section Pre-Bainitic sclerosis plastic mould steel head section hardness of embodiment 1 distributes.
The super-section Pre-Bainitic sclerosis plastic mould steel afterbody section hardness of Fig. 4 embodiment 1 distributes.
Fig. 5 is the super-section Pre-Bainitic sclerosis plastic mould sheetmetal line etching case of embodiment 1.
Fig. 6 is the super-section Pre-Bainitic hardening die steel CCT curve of embodiment 2.
Fig. 7 is the metallographic structure of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 2.
Fig. 8 is that the head section hardness of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 2 distributes.
The afterbody section hardness of the super-section Pre-Bainitic sclerosis plastic mould steel of Fig. 9 embodiment 2 distributes.
Figure 10 is the super-section Pre-Bainitic sclerosis plastic mould sheetmetal line etching case of embodiment 2.
Figure 11 is the super-section Pre-Bainitic hardening die steel CCT curve of embodiment 3.
Figure 12 is the metallographic structure of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 3.
Figure 13 is that the head section hardness of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 3 distributes.
Figure 14 is that the afterbody section hardness of the super-section Pre-Bainitic sclerosis plastic mould steel of embodiment 3 distributes.
Figure 15 is the super-section Pre-Bainitic sclerosis plastic mould sheetmetal line etching case of embodiment 3.
Figure 16 is the pre-hardening die steel CCT curve of comparative example 1.
Figure 17 is the metallographic structure of the pre-hardening plastic mould steel of comparative example 1.
Figure 18 is that the head section hardness of the pre-hardening plastic mould steel of comparative example 1 distributes.
Figure 19 is that the afterbody section hardness of the pre-hardening plastic mould steel of comparative example 1 distributes.
Figure 20 is the pre-hardening plastic mould sheetmetal line etching case of comparative example 1.
Figure 21 is the pre-hardening die steel CCT curve of comparative example 2.
Figure 22 is the metallographic structure of the pre-hardening plastic mould steel of comparative example 2.
Figure 23 is that the head section hardness of the pre-hardening plastic mould steel of comparative example 2 distributes.
Figure 24 is that the afterbody section hardness of the pre-hardening plastic mould steel of comparative example 2 distributes.
Figure 25 is the pre-hardening plastic mould sheetmetal line etching case of comparative example 2.
Embodiment
Below in conjunction with specific embodiment, technical scheme of the present invention is elaborated.
Embodiment 1
Adopt moiety and the weight percent thereof of hot-work die steel as follows:
C is that 0.28%, Si is that 0.20%, Mn is that 2.30%, Cr is that 1.30%, Mo is 0.20%,
V is that 0.20%, P is that 0.020%, S is that 0.015%, Ni is that 0.20%, Nb is 0.08%, Fe surplus.
Technological process and the step of super-section Pre-Bainitic sclerosis plastic mould steel are as follows:
1) electrosmelting: smelt in electric arc furnace by above-mentioned alloying element proportioning, then external refining and vacuum outgas, is cast into steel ingot after heat and send forge furnace;
2) High temperature diffusion thermal treatment: Heating temperature is 1200~1250 DEG C, soaking time is 15~20h;
3) forge hot-work: will be cooled in 1150~1200 DEG C of temperature ranges and carry out multiway forging processing through the heat treated steel ingot of High temperature diffusion, and adopt two upsettings two to pull out forging mode, and always forge compression ratio >=3, final forging temperature >=850 DEG C;
4) forge rear pre-hardening processing: the rear employing of forging is air-cooled or mist is cold or water-cooled, ensure steel acquisition bainite structure, drop to 200 DEG C to temperature and reinstall below fiery process furnace;
5) tempering heat treatment: be heated to 500~550 DEG C, temper twice, is incubated stove after 20~30 hours and is chilled to below 250 DEG C, the air cooling of coming out of the stove.
The present embodiment super-section Pre-Bainitic hardening die steel is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (long × wide × thick) 2500mm × 1300mm × 1200mm module, and performance test is carried out in sampling:
A phase-change characteristic:
The CCT curve of the present embodiment steel as shown in Figure 1.
B microstructure:
The microstructure of the present embodiment steel as shown in Figure 2.
The test of C uniformity of hardness:
The section hardness test result of the present embodiment steel as shown in Figure 3.As seen from the figure, this steel has higher uniformity of hardness, and the fluctuation of whole section hardness is within the scope of ± 1.5HRC.
D dermatoglyph etching performance:
The dermatoglyph etching case of the present embodiment as shown in Figure 4.As seen from the figure, this steel has good dermatoglyph etching performance.
Embodiment 2
Adopt moiety and the weight percent thereof of hot-work die steel as follows:
C is that 0.15%, Si is that 0.10%, Mn is that 3.00%, Cr is that 1.00%, Mo is 0.30%,
V is that 0.10%, P is that 0.015%, S is that 0.025%, Ni is that 0.10%, Nb is 0.14%, Fe surplus.
The preparation method of the present embodiment super-section Pre-Bainitic sclerosis plastic mould steel is with embodiment 1, and wherein tempering is heated to 450~500 DEG C.
The present embodiment super-section Pre-Bainitic hardening die steel is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (long × wide × thick) 2500mm × 1300mm × 1200mm module, and performance test is carried out in sampling:
A phase-change characteristic:
The CCT curve of the present embodiment steel as shown in Figure 5.
B microstructure:
The microstructure of the present embodiment steel as shown in Figure 6.
The test of C uniformity of hardness:
The section hardness test result of the present embodiment steel as shown in Figure 7.As seen from the figure, change steel and have higher uniformity of hardness, the fluctuation of whole section hardness is within the scope of ± 1.5HRC.
D dermatoglyph etching performance:
The dermatoglyph etching case of the present embodiment as shown in Figure 8.As seen from the figure, this steel has good dermatoglyph etching performance.
Embodiment 3
Adopt moiety and the weight percent thereof of hot-work die steel as follows:
C is that 0.30%, Si is that 0.30%, Mn is that 2.00%, Cr is that 2.00%, Mo is 0.10%,
V is that 0.30%, P is that 0.03%, S is that 0.03%, Ni is that 0.30%, Nb is 0.10%, Fe surplus.
The preparation method of the present embodiment super-section Pre-Bainitic sclerosis plastic mould steel is with embodiment 1.
The present embodiment super-section Pre-Bainitic hardening die steel is after above-mentioned smelting and hot-work and thermal treatment, and final finished specification is (long × wide × thick) 2500mm × 1300mm × 1200mm module, and performance test is carried out in sampling:
A phase-change characteristic:
The CCT curve of the present embodiment steel as shown in Figure 9.
B microstructure:
The microstructure of the present embodiment steel as shown in Figure 10.
The test of C uniformity of hardness:
The section hardness test result of the present embodiment steel as shown in Figure 11.As seen from the figure, change steel and have higher uniformity of hardness, the fluctuation of whole section hardness is within the scope of ± 1.5HRC.
D dermatoglyph etching performance:
The dermatoglyph etching case of the present embodiment as shown in Figure 12.As seen from the figure, this steel has good dermatoglyph etching performance.
comparative example 1
718 moietys and weight percent thereof are as follows:
C is that 0.37, Si is that 0.30, Mn is that 1.40, Cr is that 2.00, Mo is that 0.20, P is that 0.020, S is that 0.003, Ni is 1.00, Fe surplus.
The preparation of employing ordinary method, trimmed size is (long × wide × thick) 2500mm × 1300mm × 1200mm module, performance test is carried out in sampling:
A phase-change characteristic:
The CCT curve of the present embodiment steel as shown in Figure 13.
B microstructure:
The microstructure of the present embodiment steel as shown in Figure 14.
The test of C uniformity of hardness:
The section hardness test result of the present embodiment steel as shown in Figure 15.As seen from the figure, change steel and have higher uniformity of hardness, the fluctuation of whole section hardness is within the scope of ± 2HRC.
D dermatoglyph etching performance:
The dermatoglyph etching case of the present embodiment as shown in Figure 16.As seen from the figure, this steel has good dermatoglyph etching performance.
comparative example 2
1.2738 moietys and weight percent thereof are as follows:
C is that 0.36, Si is that 0.30, Mn is that 1.50, Cr is that 2.00, Mo is that 0.20, P is that 0.020, S is that 0.003, Ni is 1.00, Fe surplus.
The preparation of employing ordinary method, trimmed size is (long × wide × thick) 2500mm × 1300mm × 1200mm module, performance test is carried out in sampling:
A phase-change characteristic:
The CCT curve of the present embodiment steel as shown in Figure 17.
B microstructure:
The microstructure of the present embodiment steel as shown in Figure 18.
The test of C uniformity of hardness:
The section hardness test result of the present embodiment steel as shown in Figure 19.As seen from the figure, change steel and have higher uniformity of hardness, the fluctuation of whole section hardness is within the scope of ± 3HRC.
D dermatoglyph etching performance:
The dermatoglyph etching case of the present embodiment as shown in Figure 20.As seen from the figure, this steel has good dermatoglyph etching performance.
Table 1 be steel grade of the present invention and comparative example steel grade Performance Ratio
? |
Embodiment 1 |
Embodiment 2 |
Embodiment 3 |
Comparative example 1 |
Comparative example 2 |
Hardening capacity |
Excellent |
Excellent |
Excellent |
Good |
Generally |
Uniformity of hardness |
±1.5HRC |
±1.5HRC |
±1.5HRC |
±2HRC |
±3HRC |
Dermatoglyph etching |
Excellent |
Excellent |
Excellent |
Good |
Generally |