CN111334707B - Variable cross-section spring leaf with uniform structure and grain refinement and manufacturing method thereof - Google Patents
Variable cross-section spring leaf with uniform structure and grain refinement and manufacturing method thereof Download PDFInfo
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- CN111334707B CN111334707B CN201910237869.0A CN201910237869A CN111334707B CN 111334707 B CN111334707 B CN 111334707B CN 201910237869 A CN201910237869 A CN 201910237869A CN 111334707 B CN111334707 B CN 111334707B
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23P—METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS
- B23P15/00—Making specific metal objects by operations not covered by a single other subclass or a group in this subclass
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Abstract
The invention relates to a method for manufacturing a variable cross-section spring leaf with uniform structure and refined grains, which is mainly characterized in that a heat treatment process is adopted before quenching and tempering to ensure that the structure is uniform and the grains are refined after quenching and tempering, namely precipitated phases are adjusted. After the precipitated phase adjustment treatment, fine second phase particles such as AlN, VC, V (C, N) and the like are fully dispersed and precipitated in a matrix structure, and the fine second phase particles play a role of pinning grain boundaries during subsequent quenching and heating, prevent the growth of austenite grains during heating and play a role of refining grains; the precipitated phase adjustment treatment can also obtain fine pearlite and ferrite balanced state tissues, and the austenite nucleation rate is improved and the nucleation is uniform during subsequent quenching and heating, so that the effect of finally refining the quenching and tempering grains and tissues of the variable cross-section spring piece is achieved. And (4) machining after the precipitated phase is adjusted, quenching and tempering the variable cross-section spring piece, and finally obtaining the variable cross-section spring piece with uniform structure and refined grains.
Description
Technical Field
The invention relates to a spring leaf, in particular to a spring leaf with a variable cross section, which has uniform structure and refined grains, and also relates to a manufacturing method of the spring leaf.
Background
The light weight of the steel plate spring suspension system plays an important role in reducing the weight of the whole vehicle, so that various companies are developing variable-section spring pieces at present. The automobile variable cross-section spring improves the design stress on the basis of equal stress design, has fewer pieces (also called less leaf spring) when being used compared with the traditional equal cross-section leaf spring, has the advantages of less pieces, light weight, good smoothness and the like in the design of the automobile less leaf spring, and has very important significance for realizing the light weight of the whole automobile and improving the smoothness and riding comfort of the whole automobile. The basic process of the variable cross-section spring piece comprises blanking, variable cross-section rolling, machining, quenching and tempering and stress shot blasting. In the quenching and heat preservation processes of the traditional spring piece, crystal grains are easy to coarsen due to overhigh temperature or overlong time, and the elastic limit and the fatigue limit of the spring piece are reduced. The microalloy spring leaf is added with V, N, Al microalloy elements on the basis of the original material, and second phase particles generated by the microalloy elements can be dispersed and precipitated to pin the grain boundary and block the movement of the grain boundary, thereby achieving the effect of refining the grain. However, if the heat treatment temperature or the holding time is not properly set, the second phase particles are dissolved or grown, and the function of pinning the grain boundaries is lost.
Disclosure of Invention
In order to prevent the grain growth phenomenon of the variable cross-section spring piece and fully play the pinning effect of a second phase formed by microalloy elements during dispersion distribution, the invention provides a method for performing precipitated phase adjustment treatment once before quenching of the variable cross-section spring piece so as to precipitate the second phase in a dispersion manner.
The precipitated phase adjustment treatment specifically comprises:
s1, heating the spring piece to 1150-1250 ℃ for austenitizing, and keeping the temperature for not less than 60min to fully dissolve the microalloy elements into austenite; above 1150 deg.C mainly to make the second phase particles fully dissolved in austenite, and above 1250 deg.C to prevent the spring leaf from generating other abnormal structures due to too high temperature. The heat preservation time is determined according to the size of the spring piece material, the heat preservation time is 60min when the root size of the spring piece is smaller than 20mm, and if the root size is larger than 20mm, a certain time needs to be properly prolonged to ensure that the material is completely austenitized and the second phase particles are fully dissolved.
Cooling to 800-900 ℃ at a cooling speed of 0.5-3.0 ℃/s, and keeping the temperature for 30-60 min to ensure that fine second phase particles are fully dispersed and separated out;
s3, rapidly cooling to 580-650 ℃ at a cooling speed of more than 2.0 ℃/S, and keeping the temperature for more than 60 min;
and S4, cooling the furnace to room temperature to obtain pearlite and ferrite structures with fine interlamellar spacings, and simultaneously precipitating fine second phase particles from the interphase.
The quenching temperature of the variable cross-section spring piece is 920 ℃, and the heat preservation time is 40 min. In order to inhibit the growth of grain size of the spring leaf during quenching and heat preservation, the spring leaf is austenitized at the temperature of 1150-1250 ℃, the heat preservation time is 60min when the root size of the spring leaf is less than 20mm, the heat preservation time is properly prolonged when the root size is larger, so that micro alloy elements such as V, N, Al and the like are fully dissolved in austenite, and the micro alloy elements are precipitated in a stable second phase form in steel, thereby playing the role of inhibiting the growth of the grain. Then cooling to 800-900 ℃ at a cooling speed of 0.5-3.0 ℃/s, and keeping the temperature for no more than 90min, so that second phase particles such as AlN, VC, V (C, N) and the like are fully dispersed and separated out. And then rapidly cooling to 580-650 ℃ at a cooling speed of more than 2.0 ℃/s, preserving the temperature for more than 60min, wherein the austenite is more fully transformed to a balanced structure, a pearlite and ferrite structure with fine lamellar spacing is obtained, meanwhile, fine second-phase particles such as VC and the like are precipitated and separated out in interphase, and finally, the second-phase particles are cooled to room temperature in a furnace and have different particle sizes, and are nano-scale at minimum.
After the precipitated phase adjustment treatment process is finished, austenite grains are effectively pinned by the second phase grains at high temperature without coarsening when the material is quenched and insulated again; the precipitated phase adjustment treatment can also obtain fine pearlite and ferrite equilibrium state structures, and the austenite nucleation rate is improved and the nucleation is uniform during subsequent quenching and heating, so that the effects of uniform structures and grain refinement are achieved.
The variable cross-section spring leaf with uniform structure and refined crystal grains is characterized in that the variable cross-section spring steel comprises the following chemical components in percentage by mass: c: 0.56-0.66, Si: 1.40-1.80, Mn: 0.40-0.70, P: less than or equal to 0.030, S: less than or equal to 0.030, Cr: 0.90-1.20, Ni: less than or equal to 0.35, Cu: less than or equal to 0.25, V: 0.10-0.20, N: 0.009-0.018; al: 0.01 to 0.04, and the balance of Fe and inevitable impurities.
The variable cross-section spring leaf with uniform structure and refined crystal grains is characterized in that the variable cross-section spring steel comprises the following chemical components in percentage by mass: c: 0.46 to 0.54, Si: 0.17 to 0.37, Mn: 0.50-0.80, P: less than or equal to 0.030, S: less than or equal to 0.030, Cr: 0.80-1.10, Ni: less than or equal to 0.35, Cu: less than or equal to 0.25, V: 0.10-0.20, N: 0.009-0.018; al: 0.01 to 0.04. By carrying out precipitated phase adjustment treatment on the variable cross-section spring steel added with micro-alloy elements such as V, N, Al and the like, second phase particles such as AlN, VC, V (C, N) and the like are fully dispersed and precipitated, and the particle sizes of the particles are different and can reach nano-scale at least.
The invention has the beneficial effects that: the precipitated phase adjustment treatment method is adopted to carry out heat treatment on the variable cross-section spring steel such as 60Si2CrVA, 50CrVA and the like added with micro alloy elements such as V, N, Al and the like, and the grain size after quenching is detected. Tests show that when the precipitated phase adjustment treatment is carried out at the higher temperature of 1150 ℃ and 1250 ℃, the quenched crystal grains are fine, and the equivalent diameter of the crystal grains is about 20 mu m; the crystal grains of the variable cross-section spring leaf which is not subjected to precipitated phase adjustment treatment are coarsened to about 41um after quenching. The precipitated phase adjusting treatment method can effectively control a large amount of second phase particles to be dispersed and precipitated and prevent the crystal grains from growing during quenching and heat preservation, and the uniform structure and the refined quenched and tempered crystal grains are achieved.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
Example 1
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 60Si2CrVA variable cross-section spring steel, and the chemical components (mass fraction percent) are as follows: c: 0.56, Si: 1.40, Mn: 0.40, P: 0.030, S: 0.030, Cr: 0.90, Ni: 0.35, Cu: 0.25, V: 0.10, N: 0.009; al: 0.01. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1150 ℃, preserving the heat for 60min, then cooling to 800 ℃ at a cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at a cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is subjected to heat preservation at 920 ℃ for 40min, and then oil cooling quenching is carried out, wherein the equivalent diameter of the quenched crystal grains is about 24um, and the crystal grains are fine.
Example 2
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 60Si2CrVA variable cross-section spring steel, and the chemical components (mass fraction percent) are as follows: c: 0.50, Si: 1.50, Mn: 0.60, P: 0.030, S: 0.030, Cr: 1.00, Ni: 0.35, Cu: 0.25, V: 0.15, N: 0.012; al: 0.03. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1250 ℃, preserving the heat for 60min, then cooling to 900 ℃ at the cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at the cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is subjected to heat preservation at 920 ℃ for 40min, and then oil cooling quenching is carried out, wherein the equivalent diameter of the quenched crystal grains is about 18um, and the crystal grains are fine.
Example 3
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 60Si2CrVA variable cross-section spring steel, and the chemical components (mass fraction percent) are as follows: c: 0.60, Si: 1.80, Mn: 0.70, P: 0.030, S: 0.030, Cr: 1.20, Ni: 0.35, Cu: 0.25, V: 0.20, N: 0.018; al: 0.04. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1250 ℃, preserving the heat for 60min, then cooling to 800 ℃ at a cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at a cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is subjected to heat preservation at 920 ℃ for 40min, and then oil cooling quenching is carried out, wherein the equivalent diameter of the quenched crystal grains is about 21 mu m, and the crystal grains are fine.
Example 4
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 50CrVA variable cross-section spring steel, wherein the chemical components (mass fraction percent) are C: 0.46, Si: 0.17, Mn: 0.50, P: 0.030, S: 0.030, Cr: 0.80, Ni: 0.35, Cu: 0.25, V: 0.10, N: 0.009; al: 0.01. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1150 ℃, preserving the heat for 60min, then cooling to 800 ℃ at a cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at a cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is subjected to heat preservation at 920 ℃ for 40min, and then oil cooling quenching is carried out, wherein the equivalent diameter of the quenched crystal grains is about 22um, and the crystal grains are fine.
Example 5
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 50CrVA variable cross-section spring steel, wherein the chemical components (mass fraction percent) are C: 0.48, Si: 0.27, Mn: 0.60, P: 0.030, S: 0.030, Cr: 0.95, Ni: 0.25, Cu: 0.15, V: 0.20, N: 0.010; al: 0.02. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1250 ℃, preserving the heat for 60min, then cooling to 900 ℃ at the cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at the cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is kept at 920 ℃ for 40min, and then oil cooling quenching is carried out, the equivalent diameter of the quenched crystal grains is about 20um, and the crystal grains are fine.
Example 6
A method for manufacturing a variable cross-section spring piece with uniform structure and refined grains comprises the following steps: blanking → rolling with variable cross section → adjustment treatment of precipitated phase → machining → quenching and tempering → stress peening, etc. The raw material is prepared by adding V, N, Al microalloy elements on the basis of 50CrVA variable cross-section spring steel, wherein the chemical components (mass fraction percent) are C: 0.54, Si: 0.37, Mn: 0.80, P: 0.030, S: 0.030, Cr: 1.10, Ni: 0.25, Cu: 0.15, V: 0.20, N: 0.018; al: 0.04. the precipitated phase adjustment treatment is carried out on the solution by the specific method: raising the temperature to 1250 ℃, preserving the heat for 60min, then cooling to 900 ℃ at the cooling speed of 0.5-3.0 ℃/s, preserving the heat for 45min, then rapidly cooling to 600 ℃ at the cooling speed of more than 2.0 ℃/s, preserving the heat for 80min, and finally furnace-cooling to room temperature. Then the material is kept at 920 ℃ for 40min, and then oil cooling quenching is carried out, the equivalent diameter of the quenched crystal grains is about 20um, and the crystal grains are fine.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. Therefore, the protection scope of the present invention shall be subject to the protection scope defined by the claims.
Claims (4)
1. A manufacturing method of a variable cross-section spring piece with uniform structure and refined grains is characterized by mainly comprising the working procedures of blanking, variable cross-section rolling, machining, quenching and tempering and stress shot blasting, and is characterized in that: a precipitated phase adjusting treatment process is arranged between the variable cross-section rolling and the machining, and the precipitated phase adjusting treatment specifically comprises the following steps:
s1, heating the spring piece to 1150-1250 ℃ for austenitizing, and keeping the temperature for not less than 60min to fully dissolve the microalloy elements into austenite;
s2, cooling to 800-900 ℃ at a cooling speed of 0.5-3.0 ℃/S, and keeping the temperature for no more than 90min to ensure that second phase particles are fully dispersed and separated out;
s3, rapidly cooling to 580-650 ℃ at a cooling speed of more than 2.0 ℃/S, and keeping the temperature for more than 60 min;
s4, cooling the furnace to room temperature to obtain pearlite and ferrite tissues with fine interlamellar spacing, and precipitating fine second phase particles between phases;
the fine second phase particles are one or more of AlN, VC and V (C, N).
2. The method as claimed in claim 1, wherein the second phase particles have different sizes and are nano-sized as minimum.
3. The method as claimed in claim 1, wherein the holding time is 60min when the root size of the spring plate is less than 20mm, and the holding time is more than 60min when the root size of the spring plate is more than 20 mm.
4. The method as claimed in claim 1, wherein the spring leaf 50CrVA has the following chemical compositions by mass percent: c: 0.46 to 0.54, Si: 0.17 to 0.37, Mn: 0.50-0.80, P: less than or equal to 0.030, S: less than or equal to 0.030, Cr: 0.80-1.10, Ni: less than or equal to 0.35, Cu: less than or equal to 0.25, V: 0.10-0.20, N: 0.009-0.018; al: 0.01 to 0.04; by carrying out precipitated phase adjustment treatment on the variable cross-section spring piece added with V, N, Al microalloy elements, second phase particles of AlN, VC and V (C, N) are fully dispersed and precipitated, and the particle sizes of the particles are different and can reach nano-scale at least.
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| CN201811552116 | 2018-12-18 | ||
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| WO2017039012A1 (en) * | 2015-09-04 | 2017-03-09 | 新日鐵住金株式会社 | Steel wire for springs, and spring |
| KR101745191B1 (en) * | 2015-12-04 | 2017-06-09 | 현대자동차주식회사 | Ultra high strength spring steel |
| JP6356309B1 (en) * | 2016-10-19 | 2018-07-11 | 三菱製鋼株式会社 | High-strength spring, method for manufacturing the same, steel for high-strength spring, and method for manufacturing the same |
| CN107557671B (en) * | 2017-10-26 | 2019-05-14 | 山东汽车弹簧厂淄博有限公司 | Microalloying spring steel and preparation method thereof |
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