CN103361545A - High-nitrogen high-strength automotive steel - Google Patents
High-nitrogen high-strength automotive steel Download PDFInfo
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- CN103361545A CN103361545A CN2012100889083A CN201210088908A CN103361545A CN 103361545 A CN103361545 A CN 103361545A CN 2012100889083 A CN2012100889083 A CN 2012100889083A CN 201210088908 A CN201210088908 A CN 201210088908A CN 103361545 A CN103361545 A CN 103361545A
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Abstract
The invention provides high-nitrogen high-strength automotive steel which comprises the following chemical components in percent by mass: 0.04-0.08 percent of C, 0.1-0.4 percent of N, 0.2-1.0 percent of Si, 2.0-5.0 percent of Mn, less than or equal to 0.01 percent of P, less than or equal to 0.005 percent of S, 0.02-0.04 percent of Als and the balance of Fe and inevitable impurities. The martensite content in a microscopic structure of the steel is 80-92 percent, and the austenite content is 8-20 percent. Precious metals such as Nb, Ti and Mo are not added into the steel, and therefore the production cost is low; the steel is high in N content and high in corrosion resistance; and the steel also has a certain amount of residual austenite after deformation, and the energy can be effectively absorbed during collision.
Description
Technical field
The invention belongs to the steel products technical field, relate generally to the high-strength vehicle steel, especially have the high-strength vehicle steel of high nitrogen component.
Background technology
The research that acts in steel along with the nitrogen element deepens continuously, and the beneficial effect of nitrogen in steel comes into one's own day by day.Because nitrogen enlarges the austenite phase region, strongly reduces the M of steel
sPoint and the effects such as solidity to corrosion that increase substantially steel.Both at home and abroad develop many high nitrogen stainless steels.But the research of domestic and international high nitrogen steel mainly concentrates on high nitrogen stainless steel at present, and mostly based on Gao Ge, Gao Meng, tissue mostly is single austenite to this class steel on Composition Design, there is no patent and the research report of high N high-strength automobile steel both at home and abroad.
" progress of High-Nitrogen Low-Nickel Austenitic Stainless Steels " (" material Leader ", Vol9.12 (2005) p.64) have introduced the effect of nitrogen in austenitic stainless steel, lay special stress on the substitution effect of nitrogen to nickel; " high nitrogen base steel plinth research and application progress " (" China is metallurgical ", Vol7.7 (2007) p.5) has discussed the effect of nitrogen in austenitic stainless steel, ferritic stainless steel, duplex stainless steel; " cold deformation is on the impact of high-nitrogen austenitic stainless steel tissue and mechanical behavior " (" Acta Metallurgica Sinica ", Vol.43 (2005) p.64) have introduced the impact of nitrogen on several austenite stainless steel mechanical properties.Publication number is CN101693984A, also is the austenitic stainless steel that contains Gao Ge in the related steel of the Chinese patent of by name " low high Mn-N austenitic stainless steel of nickel of the high chromium of resource-conserving and preparation method thereof ".The research of these documents all concentrates on the effect of nitrogen in stainless steel, and the composition of steel contains higher chromium bar none.
Summary of the invention
The object of the present invention is to provide a kind of tensile strength more than the 1000MPa, unit elongation at the automobile more than 10% with high nitrogen steel.
The present invention is achieved in that the present invention Mn in the ultralow C-is that composition of steel is the basis, its microstructure is mainly martensite and austenite, wherein the martensite volume fraction is 80%～92%, austenite is 8%～20%, the chemical ingredients mass percent of steel is: C 0.04%～0.08%, N0.1%～0.4%, Si 0.2%～1.0%, Mn 2.0%～5.0%, P≤0.01%, S≤0.005%, Als0.02%～0.04%, surplus are Fe and inevitable impurity.
The Composition Design of the high-strength automobile steel of high nitrogen explanation among the present invention:
C: fully avoid Peritectic Reaction for guaranteeing that the Non-carbonized phase reaches in the steel microscopic structure, do not worsen plasticity and the welding property of steel plate simultaneously, take lower carbon content.Therefore, C is controlled at 0.04%～0.08%.
Si: silicon is effective solution strengthening element in steel, adds according to the intensity needs.In addition, Si also can decompose by the establishment residual austenite, prevents that carbide from generating.If its amount surpasses 1.0% plasticity, weldability and the plasticity that can worsen steel plate, therefore, be selected between 0.2%～1.0%.
Mn: the energy crystal grain thinning also reduces Ar3, enlarges the austenite phase region, postpones perlitic transformation, suppresses ferritic generation, and manganese also has the effect of solution strengthening simultaneously, but too high manganese then makes steel be difficult to processing.The too low ferrite transformation that then easily occurs of manganese is so be selected between 2.0%～5.0%.
Als: if less than 0.02%, can cause oxygen content in steel to increase, and not only can cause continous casting sprue to stop up greater than 0.04%, and can cause generating in the steel AlN, reduce the content of solid solution N, the effect of reduction N.Therefore the content with Als is controlled at 0.02%～0.04%.
Among the present invention, N adds as useful alloying element, can enlarge the austenite phase region, has compared better solid solution strengthening effect with C, and simultaneously, the increase of N content is conducive to improve the solidity to corrosion of steel.If nitrogen content is crossed the low beneficial effect that can not bring into play nitrogen.But too high N will significantly increase the smelting difficulty, increase substantially metallurgical cost, therefore N will be controlled at 0.1%～0.4%.
P, S are inevitable impurity in the steel, have worsened the plasticity of steel plate, therefore under the condition that the smelting ability allows, P is controlled at≤0.01%, S is controlled at≤0.005%.
The high N high-strength automobile steel of the present invention adopts the production method of common cold-rolled steel sheet, and concrete steps are as follows:
1) smelts: smelt by design mix.
2) hot rolling: 1200～1250 ℃ were incubated more than 150 minutes, 1100～1200 ℃ of start rolling temperatures, and 780～820 ℃ of finishing temperatures, 680～720 ℃ are batched.
3) cold rolling: draft is not less than 70%.
4) annealing: 860～920 ℃ of Heating temperatures are chilled to room temperature to be not less than 30 ℃/s speed.
Steel grade of the present invention does not add the noble metals such as Nb, Ti, Mo, and production cost is low; N content is high, and its solidity to corrosion is better than common high-strength automobile steel; Owing to a certain amount of residual austenite is still arranged in the steel after the distortion, effective absorbed energy when bumping.
Description of drawings
Accompanying drawing 1 is the microstructure-martensite of steel of the present invention+austenite.
Accompanying drawing 2 is austenite between the fine structure-martensite lath of steel of the present invention+lath.
Accompanying drawing 3 is the XRD curve (austenite percent by volume 15%) of steel before the moulding.
Accompanying drawing 4 is the XRD curve (austenite percent by volume 6%) of steel after the moulding.
Accompanying drawing 5 is placed in the air etch state contrast photo after 15 days for steel of the present invention (left side) and same level ordinary steel (right side) through hundred 1% aqueous hydrochloric acid etches.
Embodiment
The present invention is further illustrated below by embodiment.
The embodiment of the invention is as follows: strand is heated to 1230 ℃, is incubated and carries out roughing after 2.5 hours, then 7 passages are depressed greatly finish rolling, draft＞60%, and 795 ℃ of finishing temperatures, 700 ℃ are batched.Total reduction is 75% when cold rolling, and annealing temperature is 900 ℃, is chilled to room temperature with 35 ℃/s.
The concrete steel grades of the embodiment of the invention sees Table 1, and the performance index of steel plate see Table 2.
The smelting component (wt, %) of table 1 embodiment of the invention steel
| Embodiment | C | Si | Mn | P | S | Als | N |
| 1 | 0.06 | 0.215 | 3.15 | 0.008 | 0.005 | 0.030 | 0.102 |
| 2 | 0.06 | 0.210 | 4.16 | 0.01 | 0.003 | 0.028 | 0.100 |
| 3 | 0.07 | 0.450 | 3.18 | 0.008 | 0.003 | 0.036 | 0.223 |
| 4 | 0.06 | 0.470 | 4.22 | 0.009 | 0.004 | 0.031 | 0.230 |
| 5 | 0.05 | 0.810 | 3.14 | 0.01 | 0.003 | 0.038 | 0.386 |
The performance of table 2 embodiment of the invention steel and austenite percent by volume
| Embodiment | Rel(MPa) | Rm(MPa) | A 50(％) | Austenite percent by volume (%) |
| 1 | 710 | 1080 | 15 | 16 |
| 2 | 740 | 1140 | 12 | 14 |
| 3 | 750 | 1180 | 17 | 19 |
| 4 | 770 | 1210 | 14 | 14 |
| 5 | 710 | 1300 | 11 | 13 |
Claims (2)
1. one kind high N high-strength automobile steel, the chemical ingredients mass percent that it is characterized in that steel is: C 0.04%～0.08%, N 0.1%～0.4%, Si 0.2%～1.0%, Mn 2.0%～5.0%, P≤0.01%, S≤0.005%, Als 0.02%～0.04%, surplus is Fe and inevitable impurity.
2. high N high-strength automobile steel according to claim 1 is characterized in that martensite counts 80%～92% with volume fraction in the microstructure of steel, and austenite is 8%～20%.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2012100889083A CN103361545A (en) | 2012-03-30 | 2012-03-30 | High-nitrogen high-strength automotive steel |
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| CN2012100889083A CN103361545A (en) | 2012-03-30 | 2012-03-30 | High-nitrogen high-strength automotive steel |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101638749A (en) * | 2009-08-12 | 2010-02-03 | 钢铁研究总院 | Automobile steel with low cost and high strength ductility balance and preparation method thereof |
| CN101736658A (en) * | 2009-12-24 | 2010-06-16 | 燕山大学 | High-nitrogen austenitic steel high-speed railway crossing and manufacturing method thereof |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101638749A (en) * | 2009-08-12 | 2010-02-03 | 钢铁研究总院 | Automobile steel with low cost and high strength ductility balance and preparation method thereof |
| CN101736658A (en) * | 2009-12-24 | 2010-06-16 | 燕山大学 | High-nitrogen austenitic steel high-speed railway crossing and manufacturing method thereof |
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Application publication date: 20131023 |