CN119332169A - A low-strength and high-surface-hardness cold-rolled fine-blanking steel strip and its manufacturing method and application - Google Patents
A low-strength and high-surface-hardness cold-rolled fine-blanking steel strip and its manufacturing method and application Download PDFInfo
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- CN119332169A CN119332169A CN202411500796.7A CN202411500796A CN119332169A CN 119332169 A CN119332169 A CN 119332169A CN 202411500796 A CN202411500796 A CN 202411500796A CN 119332169 A CN119332169 A CN 119332169A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 57
- 239000010959 steel Substances 0.000 title claims abstract description 57
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 238000000137 annealing Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000005097 cold rolling Methods 0.000 claims abstract description 14
- 238000005098 hot rolling Methods 0.000 claims abstract description 13
- 230000008569 process Effects 0.000 claims abstract description 11
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 238000005096 rolling process Methods 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 5
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims 1
- 239000000203 mixture Substances 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 14
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 229910052799 carbon Inorganic materials 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 238000010079 rubber tapping Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- KAEAMHPPLLJBKF-UHFFFAOYSA-N iron(3+) sulfide Chemical compound [S-2].[S-2].[S-2].[Fe+3].[Fe+3] KAEAMHPPLLJBKF-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
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Abstract
本发明提供了一种低强度高表面硬度冷轧精冲钢钢带及其制造方法和应用，成分C：0.18～0.23％；Si：0.15～0.35％；Mn：0.40％～0.60％；P：≤0.020％；S：≤0.020％；Al：0.015％～0.045％，其余为Fe和不可避免的杂质。与现有技术相比，本发明通过精确控制热轧、冷轧、退火及平整工艺，获得抗拉强度和表面硬度相匹配的冷轧精冲钢产品，其抗拉强度400～500MPa，表面硬度HRB70～80，适用于厚度1.5～3.0mm汽车变速箱摩擦片精冲使用。The present invention provides a low-strength and high-surface-hardness cold-rolled fine-blanking steel strip and its manufacturing method and application, wherein the composition is C: 0.18-0.23%; Si: 0.15-0.35%; Mn: 0.40%-0.60%; P: ≤0.020%; S: ≤0.020%; Al: 0.015%-0.045%, and the rest is Fe and inevitable impurities. Compared with the prior art, the present invention obtains a cold-rolled fine-blanking steel product with matching tensile strength and surface hardness by precisely controlling the hot rolling, cold rolling, annealing and leveling processes, wherein the tensile strength is 400-500MPa and the surface hardness is HRB70-80, and the product is suitable for fine-blanking of automobile gearbox friction plates with a thickness of 1.5-3.0mm.
Description
Technical Field
The invention belongs to the field of metal material cold rolling processes, and particularly relates to a low-strength high-surface-hardness cold-rolled fine-stamped steel strip, and a manufacturing method and application thereof.
Background
Along with the technical development, the modern automobile transmission has more and more powerful design functions, the number of parts in the transmission is huge, the use condition is relatively bad, and the requirements of the automobile transmission friction plate on material strength, surface hardness, thickness precision and the like are extremely high, so that the transmission friction plate is usually produced by adopting a high-strength high-hardness cold-rolled fine-stamped steel product, but when the thickness of raw materials is thicker (1.5-3.0 mm), the high-strength high-hardness steel is difficult to finish-stamped and formed, and the dimensional precision of the parts is poor. Therefore, a cold-rolled fine blanking steel product with low tensile strength (400-500 MPa) and high hardness (HRB 70-80) and excellent comprehensive performance is needed to meet the requirements of fine blanking, forming and service performance.
The patent with publication number CN115478223A published 12/16/2022 discloses a cold-rolled fine-stamped steel strip and a preparation method thereof, wherein a large amount of C, mn and other alloy elements Cr, nb and the like are added, the content of C is 0.80% -0.90%, the content of Cr is 0.10% -0.20%, and the content of Nb is 0.02% -0.12%. The yield strength of the product prepared by high-temperature annealing at 680-750 ℃ for 14-28 h is 400-500 MPa, the tensile strength is 600-700 MPa, the elongation after break (A50) is 20-30%, and the hardness (HV 5) is 165-180HV. The product produced by the process has high hardness and tensile strength, and is unfavorable for fine blanking and forming.
The Chinese patent with publication number CN108385019A published in 2018, 8 and 10 discloses cold-rolled fine blanking steel for a locking device of an automobile child seat, which comprises the following components: C: 0.50-0.55%, si 0.15-0.35%, mn 0.80-1.10%, P less than or equal to 0.015%, S less than or equal to 0.01, cr is 0.90-1.20, V is 0.10-0.20, and Al is less than or equal to 0.035. The surface hardness of the product manufactured by multiple cold rolling and multiple annealing is HRC47-55. The process adds alloy elements Cr, V and the like with higher cost, and the hardness of the produced product is higher.
A Chinese patent with publication number CN105200308A published in 12 months 30 2015 discloses a fine-blanked steel and a manufacturing method of fine-blanked parts of an adjusting mechanism of the fine-blanked steel, wherein the fine-blanked steel comprises the following chemical components (wt%) of 0.12-0.24% of C, less than or equal to 0.40% of Si, 0.30-0.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, less than or equal to 0.40% of Cr, less than or equal to 0.40% of Ni, less than or equal to 0.10% of Mn and 0.0015-0.0040% of Ca. The tensile strength of the fine-stamped steel product produced by hot rolling, pickling, cold rolling, spheroidizing annealing and the like is 375-403 MPa, and the product is low in tensile strength due to the addition of alloy elements Cr, ni and the like with high cost.
A Chinese patent with publication number CN117265424A published in 12 months 22 of 2023 discloses a high carbon refined steel strip and a production method thereof, wherein the chemical components (wt%) of the steel strip are that C is 0.85-1.90%, si is 0.10-0.50%, mn is more than or equal to 0.85% and less than or equal to 0.8Mn+1.2Cr+1.5Nb is less than or equal to 2.52%, P is less than or equal to 0.018%, S is less than or equal to 0.010%, B is 0.002-0.010%, and the hot rolled high carbon refined steel is produced by controlling technological parameters of continuous casting, heating, rolling, cooling and slow cooling.
The Chinese patent with the publication number CN109750227A published in 5 month 14 of 2019 discloses a cold-rolled steel plate for a double-layer welded pipe with the tensile strength of 400MPa, which comprises the components of 0.12-0.18% of C, less than or equal to 0.05% of Si, 0.2-0.6% of Mn, less than or equal to 0.025% of P, less than or equal to 0.020% of S, 0.01-0.06% of Alt, less than or equal to 0.004% of N, and the balance of Fe and unavoidable inclusion elements, wherein the tensile strength is 400-500MPa, the hardness value is 55-65HR30Tm (which is equal to HRB 58-73), and the thickness is larger and the hardness is lower.
Therefore, it is necessary to provide a cold rolled fine blanking steel product having low cost, low tensile strength, high hardness and excellent combination properties.
Disclosure of Invention
The invention aims to provide a low-strength high-surface-hardness cold-rolled fine-stamped steel strip and a manufacturing method thereof, and a cold-rolled fine-stamped steel product with tensile strength matched with surface hardness is obtained by precisely controlling hot rolling, cold rolling, annealing and leveling processes.
The invention also aims to provide an application of the low-strength high-surface-hardness cold-rolled fine-stamped steel strip in manufacturing friction plates of automobile gearboxes.
The specific technical scheme of the invention is as follows:
The cold-rolled fine-stamped steel strip with low strength and high surface hardness comprises the following components in percentage by mass:
0.18-0.23% of C, 0.15-0.35% of Si, 0.40-0.60% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.015-0.045% of Al, and the balance of Fe and unavoidable impurities.
The tensile strength of the low-strength high-surface-hardness cold-rolled fine-stamped steel strip is 400-500 MPa, and the surface hardness is HRB 70-80.
The thickness of the low-strength high-surface-hardness cold-rolled fine-stamped steel strip is 1.5-3.0 mm.
The structure of the low-strength high-surface-hardness cold-rolled fine-stamped steel strip is ferrite, pearlite and carbide.
The invention provides a manufacturing method of a low-strength high-surface-hardness cold-rolled fine-stamped steel strip, which comprises the following steps:
Heating a plate blank, hot rolling, cold rolling, annealing and flattening.
The slab is heated, the tapping temperature of the slab is controlled to 1180-1220 ℃, the tapping temperature is too low, the finish rolling temperature cannot be guaranteed, the tapping temperature is too high, iron scales are seriously pressed in during rolling, the furnace time is too short, crystal grains are uneven, the furnace time is too long, and the surface iron scales are large.
The hot rolling is carried out, the final rolling temperature is controlled to be 860-900 ℃, the excessively low final rolling temperature is easy to roll in a two-phase zone, and the excessively high final rolling temperature is easy to form a banded structure.
And the convexity C40 is controlled to be 0.020-0.040 mm, so that the transverse thickness precision of the fine-stamped steel is improved.
The hot rolling is carried out, the coiling temperature is controlled to be 700-720 ℃, the coiling temperature is too low, and a strip-shaped structure is easy to form.
And the total rolling reduction rate of the cold rolling is controlled to be 50% -70%. If the reduction ratio is lower than this range, the plastic strain ratio of the product is lower. The rolling stability in the cold rolling process is poor due to the excessively high rolling reduction.
And (3) annealing, namely heating the whole coil of the steel strip to 620-710 ℃ at the speed of 0.5-1 ℃ per minute in a full-hydrogen hood-type annealing furnace, preserving heat for 4-10 hours, and then cooling along with the furnace. The heating speed is too high, the structural uniformity of the product is affected, the heating speed is too low, the production efficiency is affected, the heating temperature is too high, the tensile strength and hardness of the product are low, the heating temperature is too low, the product is not recrystallized, the heat preservation time is too short, the strip-shaped structure in steel is not easy to eliminate, the heat preservation time is too long, and the production efficiency is affected.
And the leveling elongation of the leveling machine is controlled to be 3% -10%. Too low a flat elongation, low tensile strength and hardness of the product, too high a flat elongation and poor plate shape of the product.
The invention provides an application of a low-strength high-surface-hardness cold-rolled fine-stamped steel strip, which is used for manufacturing friction plates of automobile gearboxes.
Aiming at the defects of the prior art, the invention provides a low-strength high-surface-hardness cold-rolled fine-stamped steel strip and a manufacturing method thereof, and a cold-rolled fine-stamped steel product with matched tensile strength and surface hardness is obtained by precisely controlling hot rolling, cold rolling, annealing and flattening processes. The design idea of the invention is as follows:
the effect of the alloying elements in the invention is mainly based on the following principle:
Carbon is the most economic and effective solid solution element, and can obviously improve the hardness and hardenability of steel, but excessive carbon easily leads to the excessive strength and hardness of the steel, so the control range of the C percentage in the invention is 0.18-0.23%;
Si is a solid solution strengthening element, so that the strength and hardness of the steel are enhanced, the liquid fluidity and the solidification property of the steel are improved, and the casting property is improved, but excessive Si can cause that oxide scales on the surface of a steel plate are not easy to remove and the surface quality of a finished product is affected, so that the control range of the percentage content of Si in the invention is 0.15-0.35%;
Mn is a solid solution strengthening element, enhances the strength of steel, can improve the stability of austenite, reduces the transformation temperature of austenite to ferrite, enlarges the hot working temperature range, is favorable for refining the grain size of ferrite, but has overhigh Mn content, and the Mn segregation degree of a casting blank is increased to form a banded structure in the continuous casting process, so that the mechanical property and the fine blanking property of the fine blanking steel are affected, and therefore, the control range of the Mn percentage content in the invention is 0.40-0.60%;
P has a small diffusion rate in ferrite, is easy to form segregation to form a banded structure, and is unfavorable for the fine blanking performance of the fine blanking steel. Therefore, the control range of the P content in the invention is less than or equal to 0.020%;
s, sulfur exists in the steel in the form of ferric sulfide (FeS), so that the ductility and toughness of the steel are reduced, and cracks are caused during forging and rolling, so that the S percentage control range is less than or equal to 0.020%;
al is used as a main deoxidizer, and aluminum has a certain effect on refined grains, but excessive Al can reduce cutting processability, so that the control range of the percentage of Al in the invention is 0.015% -0.045%.
Compared with the prior art, the method has the advantages that the cold-rolled fine-stamped steel product with the tensile strength of 400-500 MPa and the surface hardness of HRB 70-80 is obtained by precisely controlling the hot rolling, cold rolling, annealing and flattening processes, particularly by precisely controlling the combination of the annealing temperature, the heat preservation time and the flattening elongation, and is suitable for fine stamping of the friction plate of the automobile gearbox with the thickness of 1.5-3.0 mm.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1-example 2
A cold rolled fine blanking steel strip with low strength and high surface hardness comprises the following components in percentage by mass as shown in table 1, the balance being Fe and unavoidable impurities which are not shown in table 1.
Comparative example 1-comparative example 4
A cold rolled fine blanking steel strip comprises the following components in percentage by mass as shown in Table 1, the balance being Fe and unavoidable impurities which are not shown in Table 1.
Table 1 chemical compositions of examples and comparative examples, wt%
| C | Si | Mn | P | S | Al | |
| Example 1 | 0.20 | 0.25 | 0.51 | 0.016 | 0.005 | 0.032 |
| Example 2 | 0.21 | 0.24 | 0.48 | 0.013 | 0.006 | 0.041 |
| Comparative example 1 | 0.20 | 0.25 | 0.51 | 0.016 | 0.005 | 0.032 |
| Comparative example 2 | 0.21 | 0.24 | 0.48 | 0.013 | 0.006 | 0.041 |
| Comparative example 3 | 0.20 | 0.25 | 0.51 | 0.016 | 0.005 | 0.032 |
| Comparative example 4 | 0.21 | 0.24 | 0.48 | 0.013 | 0.006 | 0.041 |
The components of example 1 and comparative examples 1 and 3 are the same. The components of example 2 were the same as those of comparative examples 2 and 4.
The manufacturing method of the cold rolled fine blanking steel strip of each of the above examples and comparative examples includes the following steps:
Heating a plate blank, hot rolling, cold rolling, annealing and flattening.
And heating the plate blank, and controlling the tapping temperature of the plate blank to be 1180-1220 ℃.
And the hot rolling is carried out, and the final rolling temperature is controlled to be 860-900 ℃.
Convexity C40 is controlled to be 0.020-0.040 mm.
And the hot rolling is carried out, and the coiling temperature is controlled to be 700-720 ℃.
And the total rolling reduction rate of the cold rolling is controlled to be 50% -70%.
And (3) annealing, namely heating the whole coil of the steel strip to 620-710 ℃ at the speed of 0.5-1 ℃ per minute in a full-hydrogen hood-type annealing furnace, preserving heat for 4-10 hours, and then cooling along with the furnace.
And the leveling elongation of the leveling machine is controlled to be 3% -10%.
The main production process parameters and the tensile strength and surface hardness results measured according to GB/T228.1, GB/T230.1 are shown in Table 2.
Table 2 main process parameters and properties of each of examples and comparative examples
As can be seen from the above examples, the fine-stamped steel produced by the method has uniform product performance with thickness specification of 1.5-3.0 mm, tensile strength of 400-500 MPa and surface hardness of HRB 70-80, has good matching between the tensile strength and the surface hardness, and is beneficial to the fine-stamping forming of the cold-rolled fine-stamped steel with thick specification.
Comparative example 1 was low in tensile strength and surface hardness due to low flat elongation. Comparative example 2 did not meet the requirements of the present invention because of low elongation at flatness and low surface hardness. Comparative example 3 has a high tensile strength and surface hardness due to a low annealing temperature and a high flat elongation. Comparative example 4 has a high tensile strength due to a low annealing temperature and a short holding time.
The above underlined are data that do not meet the requirements of the present invention.
The above embodiments are described in order to facilitate the understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications can be readily made to these embodiments and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above-described embodiments, and those skilled in the art, based on the present disclosure, should make improvements and modifications without departing from the scope of the present invention.
Claims (10)
1. The cold-rolled fine blanking steel strip with low strength and high surface hardness is characterized by comprising the following components in percentage by mass:
0.18-0.23% of C, 0.15-0.35% of Si, 0.40-0.60% of Mn, less than or equal to 0.020% of P, less than or equal to 0.020% of S, 0.015-0.045% of Al, and the balance of Fe and unavoidable impurities.
2. The low-strength high-surface-hardness cold-rolled fine-stamped steel strip according to claim 1, wherein the low-strength high-surface-hardness cold-rolled fine-stamped steel strip has a tensile strength of 400-500 mpa and a surface hardness of HRB 70-80.
3. The low-strength high-surface hardness cold-rolled fine blanking steel strip as claimed in claim 1, wherein the thickness of the low-strength high-surface hardness cold-rolled fine blanking steel strip is 1.5-3.0 mm.
4. A method of manufacturing a low strength high surface hardness cold rolled fine blanked steel strip according to any one of claims 1-3, characterized in that the manufacturing method comprises the following process:
Heating a plate blank, hot rolling, cold rolling, annealing and flattening.
5. The method according to claim 4, wherein the hot rolling is performed at a controlled finish rolling temperature of 860 ℃ to 900 ℃.
6. The method according to claim 4, wherein the convexity C40 is controlled to 0.020-0.040 mm, and the coiling temperature is controlled to 700-720 ℃.
7. The method according to claim 4, wherein the cold rolling is performed with a total rolling reduction of 50% to 70%.
8. The method according to claim 4, wherein the whole roll of the annealed steel strip is heated to 620-710 ℃ in a full hydrogen hood-type annealing furnace at a speed of 0.5-1 ℃ per minute, kept for 4-10 hours, and then cooled with the furnace.
9. The method of claim 4, wherein the flattening, flattening elongation is controlled to be between 3% and 10%.
10. Use of a low strength high surface hardness cold rolled fine blanked steel strip according to any of claims 1-3 for manufacturing friction plates for automotive gearboxes.
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| CN202411500796.7A CN119332169A (en) | 2024-10-25 | 2024-10-25 | A low-strength and high-surface-hardness cold-rolled fine-blanking steel strip and its manufacturing method and application |
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