CN113930681A - High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof - Google Patents
High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof Download PDFInfo
- Publication number
- CN113930681A CN113930681A CN202111152411.9A CN202111152411A CN113930681A CN 113930681 A CN113930681 A CN 113930681A CN 202111152411 A CN202111152411 A CN 202111152411A CN 113930681 A CN113930681 A CN 113930681A
- Authority
- CN
- China
- Prior art keywords
- temperature
- equal
- hardenability
- steel
- fatigue
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- 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
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
-
- 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
- C22C33/06—Making ferrous alloys by melting using master alloys
-
- 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
-
- 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
-
- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
-
- 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
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
-
- 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
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention discloses a high-hardenability high-fatigue-life low-temperature-resistant spring flat steel which comprises the following chemical components in percentage by weight: c: 0.50 to 0.65 wt%, Si: 0.40-0.90 wt%, Mn: 0.80-1.50 wt%, P is less than or equal to 0.025 wt%, S is less than or equal to 0.025 wt%, Cr: 0.50 to 1.25 wt%, Ni: 0.10 to 0.40%, Ti: 0.05 to 0.08 wt%, B: 0.002 to 0.006 wt%, Zr: 0.002-0.009 wt%, N is less than or equal to 0.0045 wt%, H is less than or equal to 0.00012 wt%, O is less than or equal to 0.0011 wt%, Mo: 0.10 to 0.65 wt%, and the balance Fe and inevitable impurities. The invention develops the following performance requirements through the innovation of components and process: ReL is more than or equal to 1750MPa, Rm is more than or equal to 1950MPa, A is more than or equal to 10 percent, Z is more than or equal to 36 percent, and hardenability J25 is more than or equal to 58 HRC; the fatigue life of the steel plate spring reaches more than 15 ten thousand times under the highest design stress of 1050 MPa; the-60 ℃ KV2 is more than or equal to 35J spring flat steel.
Description
Technical Field
The invention relates to a long steel product and a production method thereof, belongs to the field of ferrous metallurgy production and manufacturing, and particularly relates to a high-hardenability, high-fatigue-life and low-temperature-resistant spring flat steel and a production method thereof.
Background
The weight reduction of automobiles inevitably requires the weight reduction of automobile parts. The heavy-duty car adopts high-strength spring flat steel and can reduce 30% -50% of the self mass of the steel plate spring assembly, and the total weight of the steel plate spring is reduced by improving the thickness of each flat steel and reducing the total number of assembled sheets, so that the aim of lightening the car parts is fulfilled. The current technical path is as follows: multiple leaf springs → few leaf springs → single leaf spring.
On one hand, the spring flat steel is used after being subjected to quenching and tempering heat treatment, the requirement on the hardenability of the steel is higher and higher along with the increase of the thickness of the steel, otherwise, once the steel cannot be quenched, the metallurgical structure is not appropriate and the strength is reduced, and the damping purpose of the steel plate spring cannot be met.
On the other hand, with social progress and industrial development, the safety requirement of automobiles is higher and higher, and although the national standard requirement of the fatigue life of the steel plate spring is not less than 8 ten thousand times at present, most domestic famous host factories require not less than 10 ten thousand times, even not less than 12 ten thousand times. The high fatigue life spring flat steel can ensure that the plate spring component cannot be damaged due to premature fatigue under the action of long-term vibration and alternating stress.
Meanwhile, with the development requirements of the logistics transportation industry and resource exploitation engineering, many projects in China have been expanded to various extremely cold fields. In the wide northern areas of China, such as northeast and Xinjiang, the temperature in winter can reach below-40 ℃, and the temperature in some areas is lower than-50 ℃. Under the condition of low temperature, the performance of the spring flat steel can be greatly changed, and the mechanical properties, especially the impact toughness and the fracture toughness, shown at different environmental temperatures are greatly changed. The high or low toughness in low temperature environment will affect the service performance of the whole automobile, even the safety and reliability.
Before the invention is put forward, the similar technical products related to the field of manufacturing of the high-hardenability high-fatigue-life low-temperature-resistant steel are few, and particularly, the invention aims at the aspects of the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel.
Chinese patent application No. CN 200610081227.9 discloses a high-strength spring steel with excellent fatigue resistance, which is mainly suitable for high-strength spring steel with tensile strength of over 1800MPa and excellent fatigue failure resistance. The steel comprises the following specific chemical components in percentage by weight: 0.35-0.55% of C, 1.70-2.50% of Si, 0.40-0.70% of Mn, 0.70-1.10% of Cr0.05-0.20% of V, 0.005-0.10% of RE, 0.0005-0.020% of Ca, less than or equal to 0.020% of P, less than or equal to 0.015% of S, less than or equal to 0.0015% of O, and the balance of Fe and other inevitable impurities. The steel further contains 0.0005 to 0.0030% of B, 0.01 to 0.10% of Ti, or 0.01 to 1.50% of Ni. The steel of the present invention contains a relatively high Si content, has a very high tendency to oxidation and decarburization, and is not favorable for fatigue resistance.
Chinese patent application No. CN 200510018800.7 discloses a high strength and toughness high hardenability spring flat steel, which is characterized in that: the chemical components (weight percentage) are as follows: 0.48-0.55% of C, 0.17-0.37% of Si, 0.70-1.00% of Mn, 0.80-1.10% of Cr, 0.001-0.004% of B, less than or equal to 0.35% of Ni, less than or equal to 0.25% of Cu, less than or equal to 0.03% of P, less than or equal to 0.03% of S and the balance of Fe. The invention aims to provide a high-strength-toughness high-hardenability spring steel material which has the strength and toughness equivalent to 50CrVA and the hardenability equivalent to 60CrMnBA and is economical in price. The steel has poor tempering resistance, mainly has low silicon content; meanwhile, the strength grade is low, and the automobile is not suitable for lightweight development of automobiles.
Chinese patent application No. CN 201510064475.1 discloses a low temperature resistant high strength spring steel and a preparation method thereof, wherein the spring steel contains (by weight percent): the chemical components and the weight percentage thereof are as follows: 0.45 to 0.55 percent of C, 1.0 to 1.3 percent of Si, 1.2 to 1.4 percent of Mn, 3.5 to 5.5 percent of Ni, 0.8 to 1.0 percent of Cr, 0.3 to 0.5 percent of Cu, 0.006 to 0.008 percent of Ti, 0.03 to 0.06 percent of Zn, 0.004 to 0.005 percent of Sn, less than or equal to 0.025 percent of P, less than or equal to 0.025 percent of S and the balance of iron. The preparation method comprises mixing the raw materials, heating to molten state, pouring into purified water, chilling, and pulverizing into powder of 100 meshes and 200 meshes; adding silane coupling agent KH-550 accounting for 3-5% of the weight of the powder and nano carbon powder accounting for 2-4% of the weight of the powder into the obtained powder, uniformly mixing, pressing the mixture into a blank under 8-15Mpa, calcining the blank for 3-4 hours at the temperature of 1000-1100 ℃, cooling and crushing the calcined blank into 150-mesh powder with the particle size of 250 meshes to obtain the powder. The steel is prepared by a powder metallurgy method, has low efficiency and high cost, and is difficult to produce and popularize on a large scale.
Disclosure of Invention
In order to meet the requirements of the spring flat steel for various trucks, buses and engineering machinery vehicles on adapting to the working conditions of high thickness, variable cross section, long fatigue life and low temperature resistance, the development of the spring flat steel with good quenching performance, high fatigue performance and low temperature toughness is urgently needed. The invention develops the following performance requirements through the innovation of components and process: ReL is more than or equal to 1750MPa, Rm is more than or equal to 1950MPa, A is more than or equal to 10 percent, Z is more than or equal to 36 percent, and hardenability J25 is more than or equal to 58 HRC; the fatigue life of the steel plate spring reaches more than 15 ten thousand times under the highest design stress of 1050 MPa; the-60 ℃ KV2 is more than or equal to 35J spring flat steel.
The technical scheme adopted by the invention for solving the problems is as follows:
a high-hardenability high-fatigue-life low-temperature-resistant spring flat steel comprises the following chemical components in percentage by weight: c: 0.50 to 0.65 wt%, Si: 0.40-0.90 wt%, Mn: 0.80-1.50 wt%, P is less than or equal to 0.025 wt%, S is less than or equal to 0.025 wt%, Cr: 0.50 to 1.25 wt%, Ni: 0.10 to 0.40%, Ti: 0.05 to 0.08 wt%, B: 0.002 to 0.006 wt%, Zr: 0.002-0.009 wt%, N is less than or equal to 0.0045 wt%, H is less than or equal to 0.00012 wt%, O is less than or equal to 0.0011 wt%, Mo: 0.10 to 0.65 wt%, and the balance Fe and inevitable impurities. The production process comprises the following steps:
(1) KR desulfurization: stirring molten iron in a ladle by adopting a composite KR desulfurization method to form a vortex, adding active lime and magnesium powder serving as desulfurizing agents twice in sequence to reduce the S content of the molten iron, and controlling the sulfur content [ S ] of the molten iron at the outlet to be less than or equal to 0.01 percent;
(2) heating a ladle: covering the ladle and heating by adopting electromagnetic induction to ensure that the temperature is more than or equal to 1490 ℃ in the process of conveying the molten iron from the iron works to the steel works;
(3) smelting in a converter, and controlling the end point C to be more than or equal to 0.06-0.40%; the tapping temperature is more than or equal to 1630 ℃;
(4) RH vacuum treatment is carried out, the vacuum degree is less than or equal to 100Pa, the vacuum keeping time is not less than 20min, the soft argon blowing flow is 20-68 NL/min, and the soft argon blowing time is 12-28 min;
(5) the section size of the continuous casting billet is 280mm multiplied by 380mm, the blank drawing speed is stably controlled at 0.70m/min, a solidification end electric stirring process is adopted, the stirring current is 350-450A, and the frequency is 8 Hz; carrying out soft reduction on the casting blank, wherein the reduction rate is 3-10%;
(6) after slowly cooling for 72h, heating the casting blank, soaking at 1210-1250 ℃ for 560-340 min, and rolling into a small square blank with the section of 160 x 160 mm;
(7) after local grinding, heating the small square billets at the soaking temperature of 1110-1148 ℃ for 110-145 min;
(8) rough rolling, controlling the initial rolling temperature: 1050-1100 ℃.
(9) And (3) finish rolling, wherein the initial rolling temperature is controlled to be 980-1060 ℃, and the accumulated deformation is 10-60%.
(10) Rolling into spring flat steel with the thickness of 35-56 mm and the width of 90-110 mm for standby.
(11) After the spring flat steel is slowly cooled, the first sub-temperature quenching temperature is 800 +/-20 ℃, the tempering temperature is 420 +/-20 ℃, the second sub-temperature quenching temperature is 800 +/-20 ℃, and the tempering temperature is 400 +/-20 ℃ for heat treatment, uniform and stable tempered sorbite is obtained, and the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel is obtained.
The following analysis explains the effects of the elements in the steel of the present invention and the production method thereof:
c: c is an extremely important element in steel, has obvious influence on the hardenability of the spring flat steel, has excellent hardenability when the content is higher, and has adverse influence on low-temperature toughness when the content is too high. The content of C in the invention is 0.50-0.65%.
Si: si is the most main contributing element for ensuring the elasticity of the spring flat steel, has obvious solid solution strengthening effect, does not form carbide, exists in the steel in a solid solution state, can improve the strength of the steel, is one of main deoxidizing elements, but has high content, and increases the decarburization and graphitization tendency of the steel. The Si content of the invention is 0.40-0.90%.
Mn: mn is dissolved in ferrite to improve the strength of the steel; is also a good deoxidizer, and reduces the O content in steel; can combine with S to form MnS, reduce the adverse effect of S on the low-temperature performance of the material, and excessively high Mn can cause the steel to become brittle and hard and reduce the toughness. The Mn content of the invention is 0.80-1.50%.
Cr: cr can effectively prevent the growth of prior austenite grains, and is favorable for hardenability and toughness of the spring flat steel when being added in a proper amount. The Cr content of the invention is 0.50-1.25%.
Ni: ni is a main alloy element of the low-temperature steel, the brittle transition temperature can be reduced while the strength is improved, the low-temperature impact toughness is improved, but the yield strength of the material can be reduced due to the excessively high content of Ni, the elastic deformation of the spring flat steel under a higher load is not facilitated, and the fatigue life of the spring flat steel in the running process of an automobile is shortened. The Mn content of the invention is 0.48-0.60%.
Ti: ti can refine crystal grains, improve strength and toughness and also improve hardenability. Meanwhile, in the heat treatment process of the spring flat steel, the coarseness of austenite grains can be avoided, and the precipitation of carbonitride of the austenite grains can play a role in precipitation strengthening, so that the quenching performance and the fatigue performance of the steel can be improved. The invention relates to a Ti: 0.05 to 0.08 wt%.
B: b is an element for improving the hardenability of the material, trace B in medium-high carbon steel can effectively reduce the segregation of P, S in a grain boundary and improve the form of oxide inclusions, and the addition of B in the steel is beneficial to combining the high strength of the steel with good weldability and cold brittleness resistance, so that the yield strength, tensile strength, fatigue strength, wear resistance, hydrogen induced intergranular fracture resistance and the like of the material are improved or improved to different degrees, but the content is too high, and the functions are weakened or even deteriorated. When the content of B is less than 0.005%, the low-temperature toughness of the steel is greatly beneficial, and when the content of B is more than the range, the B is easy to form FeB with Fe, so that the possibility of brittle fracture tendency along the crystal is greatly increased, and the low-temperature toughness of the material is damaged, wherein the content of B is 0.002-0.006%.
Zr can make the steel obtain very good low-temperature toughness, but the content of Zr also needs to be strictly controlled. The Zr content is 0.002-0.009%.
P, S: p, S it is a harmful element in the steel, the lower the content is, the better the low temperature impact energy is, considering the actual control condition of steel making, the P is controlled less than 0.025%, S is controlled less than 0.025%.
Mo: the hardenability of the steel is improved, the temper brittleness of the steel is reduced, the ductile-brittle transition temperature is reduced, and the fatigue performance is improved, wherein the content of Mo is 0.10-0.65%.
N: the important constituent elements of microalloying can strengthen the steel, but obviously reduce the toughness of the steel, and increase the aging tendency and cold brittleness, so that the N content of the invention is controlled below 0.0045 percent.
H: in steel, "hairlines" or stress zones are generated, and the hairlines are expanded during rolling or heat treatment to form cracks, which deteriorate the strength and toughness of the steel, and even cause cracking, and point-like segregation and hydrogen embrittlement, which seriously affect the fatigue life of the spring flat steel. In the invention, H is controlled below 0.00012%.
O: at a lower temperature, the strength and the toughness of the spring flat steel are both sharply reduced along with the increase of the O content, the brittle transition temperature is greatly increased, the low-temperature impact toughness is not favorable, and meanwhile, the occurrence probability of oxide inclusions is greatly increased along with the increase of the O content, so that the fatigue life of the spring flat steel is reduced. The invention controls the O content within 0.0011%.
Induction heating of the ladle: the invention adopts induction heating and covering heat preservation in the transportation process, can reduce the refractory consumption, improve the package age and improve the molten iron yield, simultaneously, the temperature rise of the molten iron can use less or no covering agent, clean the molten iron, reduce harmful elements such as S, P and the like, and lead the converter to add more steel scraps and use less molten iron, thus being beneficial to energy conservation and emission reduction of steel plants and promoting carbon neutralization.
Secondary sub-temperature quenching and tempering: the secondary quenching can refine the austenite grain size, shorten the length of lath martensite obtained after quenching, and temper the steel to obtain better strength and elongation. The austenite grains grow due to the over-high quenching temperature, a coarse-grain martensite structure is obtained after quenching, the toughness is poor, and the undissolved ferrite exists in the austenite due to the over-low quenching temperature, and the ferrite is a soft phase structure, so that the strength of the steel is reduced. The hypoeutectoid steel is quenched at the temperature of Ac 1-Ac 3, which is 40 ℃ lower than the normal subtemperature, and is beneficial to the low-temperature strength and toughness and the fatigue life of the hypoeutectoid steel.
A secondary firing forming process: the invention adopts a two-fire forming process, the residence time of the molten steel tundish in the bloom casting process is long, the removal of impurities is facilitated, meanwhile, the blank compression ratio can be increased through cogging, the structure uniformity is improved, the crystal grains are refined, the compactness and the toughness of the spring flat steel are facilitated to be improved, and the method is an important means for ensuring the low-temperature performance of the high-strength spring flat steel.
The large-compression-ratio forming process comprises the following steps: the invention adopts a rolling and material forming process with a large compression ratio, the residence time of the molten steel tundish in the process of pouring the bloom is long, the removal of impurities is facilitated, meanwhile, the casting blank compression ratio can be increased through rolling with a large deformation amount, the improvement of the tiny and uniform microscopic grains of the spring flat steel is facilitated, and the quality of high-quality metallurgical material objects and excellent manufacturing process performance are ensured.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention couples a plurality of trace alloy elements on the basis of carbon and manganese series low alloy steel, and innovatively adopts ladle induction heating, secondary sub-temperature quenching and tempering, a secondary heating material forming process and a large-compression ratio material forming process to form finer grains and uniform sorbite structures, thereby obtaining the spring flat steel with good low-temperature performance at the temperature of 60 ℃ below zero and above. 2. The spring flat steel produced by the invention comprises the following steps: ReL is more than or equal to 1600MPa, Rm is more than or equal to 1830MPa, A is more than or equal to 10 percent, Z is more than or equal to 36 percent, and hardenability J25 is more than or equal to 58 HRC; the fatigue life of the steel plate spring reaches more than 15 ten thousand times under the highest design stress of 1050 MPa; the KV2 is more than or equal to 35J at the temperature of minus 60 ℃. 3. The method has the advantages of simple production process and low production cost, and can carry out process production without greatly changing production equipment and process flow under the existing production conditions.
Detailed Description
In order to better understand the present invention, the following examples are further provided to illustrate the content of the present invention, but the present invention is not limited to the following examples.
Examples 1 to 10
The production process of the high-hardenability, high-fatigue-life and low-temperature-resistant flat spring steel disclosed by the embodiment 1-10 comprises the following steps:
(1) KR desulfurization: stirring molten iron in a ladle by adopting a composite KR desulfurization method to form a vortex, adding active lime and magnesium powder serving as desulfurizing agents twice in sequence to reduce the S content of the molten iron, and controlling the sulfur content [ S ] of the molten iron at the outlet to be less than or equal to 0.01 percent;
(2) heating a ladle: covering the ladle and heating by adopting electromagnetic induction to ensure that the temperature is more than or equal to 1490 ℃ in the process of conveying the molten iron from the iron works to the steel works;
(3) smelting in a converter, and controlling the end point C to be more than or equal to 0.06-0.40%; the tapping temperature is more than or equal to 1630 ℃;
(4) RH vacuum treatment is carried out, the vacuum degree is less than or equal to 100Pa, the vacuum keeping time is not less than 20min, the soft argon blowing flow is 20-68 NL/min, and the soft argon blowing time is 12-28 min;
(5) the section size of the continuous casting billet is 280mm multiplied by 380mm, the blank drawing speed is stably controlled at 0.70m/min, a solidification end electric stirring process is adopted, the stirring current is 350-450A, and the frequency is 8 Hz; carrying out soft reduction on the casting blank, wherein the reduction rate is 3-10%;
(6) after slowly cooling for 72h, heating the casting blank, soaking at 1210-1250 ℃ for 560-340 min, and rolling into a small square blank with the section of 160 x 160 mm;
(7) after local grinding, heating the small square billets at the soaking temperature of 1110-1148 ℃ for 110-145 min;
(8) rough rolling, controlling the initial rolling temperature: 1050-1100 ℃.
(9) And (3) finish rolling, wherein the initial rolling temperature is controlled to be 980-1060 ℃, and the accumulated deformation is 10-60%.
(10) Rolling into spring flat steel with the thickness of 35-56 mm and the width of 90-110 mm for standby.
(11) After the spring flat steel is slowly cooled, the first sub-temperature quenching temperature is 800 +/-20 ℃, the tempering temperature is 420 +/-20 ℃, the second sub-temperature quenching temperature is 800 +/-20 ℃, and the tempering temperature is 400 +/-20 ℃ to carry out heat treatment, so that uniform and stable tempered sorbite, namely the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel is obtained
Table 1 examples chemical composition wt%
| Examples | C | Si | Mn | P | S | Cr | Ni | Ti | B | Zr |
| 1 | 0.50 | 0.40 | 0.80 | 0.004 | 0.006 | 0.50 | 0.10 | 0.05 | 0.002 | 0.002 |
| 2 | 0.51 | 0.45 | 0.82 | 0.008 | 0.009 | 0.52 | 0.16 | 0.05 | 0.003 | 0.003 |
| 3 | 0.52 | 0.60 | 0.95 | 0.007 | 0.015 | 0.55 | 0.20 | 0.06 | 0.002 | 0.004 |
| 4 | 0.54 | 0.62 | 1.02 | 0.009 | 0.006 | 0.60 | 0.25 | 0.07 | 0.004 | 0.005 |
| 5 | 0.58 | 0.70 | 1.15 | 0.012 | 0.006 | 0.75 | 0.30 | 0.08 | 0.005 | 0.006 |
| 6 | 0.58 | 0.76 | 1.20 | 0.020 | 0.008 | 0.82 | 0.35 | 0.08 | 0.006 | 0.007 |
| 7 | 0.60 | 0.80 | 1.30 | 0.025 | 0.007 | 0.91 | 0.40 | 0.06 | 0.005 | 0.008 |
| 8 | 0.65 | 0.82 | 1.35 | 0.009 | 0.015 | 1.10 | 0.35 | 0.07 | 0.002 | 0.009 |
| 9 | 0.58 | 0.88 | 1.41 | 0.015 | 0.020 | 1.25 | 0.29 | 0.08 | 0.005 | 0.006 |
| 10 | 0.65 | 0.90 | 1.50 | 0.011 | 0.025 | 1.25 | 0.18 | 0.05 | 0.004 | 0.004 |
| Comparative example 1 | 0.49 | 0.39 | 0.79 | 0.026 | 0.007 | 0.49 | 0.09 | 0.09 | 0.001 | 0.001 |
| Comparative example 2 | 0.50 | 0.81 | 1.51 | 0.028 | 0.010 | 1.05 | 0.42 | 0.04 | 0.007 | 0.010 |
| Comparative example 3 | 0.65 | 0.91 | 1.36 | 0.030 | 0.020 | 1.26 | 0.41 | 0.08 | 0.008 | 0.008 |
Table 1 examples chemical composition wt% (continue)
TABLE 2 smelting Process parameters
TABLE 3 Rolling and Heat treatment Process parameters
TABLE 4 Main Performance test results of examples of the present invention and comparative examples
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many modifications and changes can be made without departing from the inventive concept of the present invention, and these modifications and changes are within the protection scope of the present invention.
Claims (10)
1. A high-hardenability high-fatigue-life low-temperature-resistant spring flat steel is characterized by comprising the following chemical components in percentage by weight: c: 0.50 to 0.65 wt%, Si: 0.40-0.90 wt%, Mn: 0.80-1.50 wt%, P is less than or equal to 0.025 wt%, S is less than or equal to 0.025 wt%, Cr: 0.50 to 1.25 wt%, Ni: 0.10 to 0.40%, Ti: 0.05 to 0.08 wt%, B: 0.002 to 0.006 wt%, Zr: 0.002-0.009 wt%, N is less than or equal to 0.0045 wt%, H is less than or equal to 0.00012 wt%, O is less than or equal to 0.0011 wt%, Mo: 0.10 to 0.65 wt%, and the balance Fe and inevitable impurities.
2. The high hardenability, high fatigue life, low temperature resistant spring flat according to claim 1, characterized in that it has the following properties: ReL is more than or equal to 1600MPa, Rm is more than or equal to 1830MPa, A is more than or equal to 10 percent, Z is more than or equal to 36 percent, and hardenability J25 is more than or equal to 58 HRC; the fatigue life reaches more than 15 ten thousand times under the highest design stress of 1050 MPa; the KV2 is more than or equal to 35J at the temperature of minus 60 ℃.
3. The production process of the low temperature resistant spring flat steel with high hardenability and fatigue life as claimed in claim 1, characterized by comprising the following steps:
(1) KR desulfurization: stirring molten iron in a ladle by adopting a composite KR desulfurization method to form a vortex, adding active lime and magnesium powder serving as desulfurizing agents twice in sequence to reduce the S content of the molten iron, and controlling the sulfur content [ S ] of the molten iron at the outlet to be less than or equal to 0.01 percent;
(2) heating a ladle: covering the ladle and heating by adopting electromagnetic induction to ensure that the temperature is more than or equal to 1490 ℃ in the process of conveying the molten iron from the iron works to the steel works;
(3) smelting in a converter;
(4) RH vacuum treatment;
(5) continuous casting, wherein the blank drawing speed of the section size of a blank is controlled, a solidification end electric stirring process is adopted, and the casting blank is lightly reduced;
(6) heating the casting blank after slow cooling, and rolling into a small square blank;
(7) after local grinding, heating the small square billet;
(8) rough rolling;
(9) fine rolling;
(10) rolling into spring flat steel;
(11) after the spring flat steel is slowly cooled, the first sub-temperature quenching temperature is 800 +/-20 ℃, the tempering temperature is 420 +/-20 ℃, the second sub-temperature quenching temperature is 800 +/-20 ℃, and the tempering temperature is 400 +/-20 ℃ for heat treatment, uniform and stable tempered sorbite is obtained, and the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel is obtained.
4. The production process of the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel according to claim 3, characterized in that in the step (3), smelting is carried out in a converter, and the end point C is controlled to be more than or equal to 0.06-0.40%; the tapping temperature is more than or equal to 1630 ℃.
5. The production process of the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel according to claim 3, characterized in that in the step (4), RH vacuum treatment is carried out, the vacuum degree is less than or equal to 100Pa, the vacuum maintaining time is not less than 20min, the soft blowing argon flow is 20-68 NL/min, and the soft blowing time is 12-28 min.
6. The production process of the low temperature resistant spring flat steel with high hardenability, high fatigue life and high temperature resistance according to claim 3, characterized in that the section size of the continuous casting billet in the step (5) is 280mm x 380mm, the drawing speed is stably controlled at 0.70m/min, a solidification end electric stirring process is adopted, the stirring current is 350-450A, and the frequency is 8 Hz; and carrying out soft reduction on the casting blank, wherein the reduction rate is 3-10%.
7. A production process of the low temperature resistant spring flat steel with high hardenability, high fatigue life and low temperature resistance according to claim 3, characterized in that after the slow cooling is carried out for 72 hours in the step (6), the casting blank is heated, the soaking temperature is 1210-1250 ℃, the furnace time is 560-340 min, and the billet is rolled into a small square billet with the section of 160 x 160 mm.
8. The production process of the low-temperature-resistant flat spring steel with high hardenability and fatigue life according to claim 3, characterized in that in the step (7), the billet is heated, the soaking temperature is 1110-1148 ℃, and the soaking time is 110-145 min.
9. The production process of the high-hardenability high-fatigue-life low-temperature-resistant spring flat steel according to claim 3, characterized in that in the step (8), rough rolling is carried out, and the initial rolling temperature is controlled as follows: 1050-1100 ℃; and (9) finish rolling, wherein the initial rolling temperature is controlled to be 980-1060 ℃, and the accumulated deformation is 10-60%.
10. The process for producing a low temperature resistant flat spring steel with high hardenability and fatigue life as claimed in claim 3, wherein the step (10) is to roll the flat spring steel with a thickness of 35-56 mm and a width of 90-110 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111152411.9A CN113930681B (en) | 2021-09-29 | 2021-09-29 | High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111152411.9A CN113930681B (en) | 2021-09-29 | 2021-09-29 | High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113930681A true CN113930681A (en) | 2022-01-14 |
| CN113930681B CN113930681B (en) | 2022-12-02 |
Family
ID=79277192
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111152411.9A Active CN113930681B (en) | 2021-09-29 | 2021-09-29 | High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113930681B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114959448A (en) * | 2022-04-21 | 2022-08-30 | 中天钢铁集团有限公司 | Efficient production method of 1900 MPa-grade steel for suspension spring |
| CN115747645A (en) * | 2022-11-04 | 2023-03-07 | 马鞍山钢铁股份有限公司 | Steel for high-toughness high-contact-fatigue high-power wind power yaw bearing ring, bearing ring and production process |
| CN115927955A (en) * | 2022-11-04 | 2023-04-07 | 马鞍山钢铁股份有限公司 | Steel for high-homogenization high-power wind power yaw bearing ring, bearing ring and production process |
| CN117230378A (en) * | 2023-11-10 | 2023-12-15 | 江苏沙钢集团淮钢特钢股份有限公司 | Steel for variable-section leaf springs of heavy-duty trucks and production process thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4770721A (en) * | 1981-08-11 | 1988-09-13 | Aichi Steel Works, Ltd. | Process of treating steel for a vehicle suspension spring to improve sag-resistance |
| CN105506504A (en) * | 2014-09-26 | 2016-04-20 | 鞍钢股份有限公司 | Ultrahigh-strength wear-resistant steel plate and production method thereof |
| CN106062229A (en) * | 2014-02-28 | 2016-10-26 | 株式会社神户制钢所 | Rolled material for high strength spring, and wire for high strength spring |
| CN106381450A (en) * | 2009-12-18 | 2017-02-08 | 爱知制钢株式会社 | Steel for leaf spring with high fatigue strength, and leaf spring parts |
| CN110629119A (en) * | 2019-10-31 | 2019-12-31 | 武汉钢铁有限公司 | Spring flat steel and manufacturing process thereof |
| CN111593268A (en) * | 2020-06-29 | 2020-08-28 | 马鞍山钢铁股份有限公司 | Heat-resistant high-strength spring steel and production method thereof |
-
2021
- 2021-09-29 CN CN202111152411.9A patent/CN113930681B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4770721A (en) * | 1981-08-11 | 1988-09-13 | Aichi Steel Works, Ltd. | Process of treating steel for a vehicle suspension spring to improve sag-resistance |
| CN106381450A (en) * | 2009-12-18 | 2017-02-08 | 爱知制钢株式会社 | Steel for leaf spring with high fatigue strength, and leaf spring parts |
| CN106062229A (en) * | 2014-02-28 | 2016-10-26 | 株式会社神户制钢所 | Rolled material for high strength spring, and wire for high strength spring |
| CN105506504A (en) * | 2014-09-26 | 2016-04-20 | 鞍钢股份有限公司 | Ultrahigh-strength wear-resistant steel plate and production method thereof |
| CN110629119A (en) * | 2019-10-31 | 2019-12-31 | 武汉钢铁有限公司 | Spring flat steel and manufacturing process thereof |
| CN111593268A (en) * | 2020-06-29 | 2020-08-28 | 马鞍山钢铁股份有限公司 | Heat-resistant high-strength spring steel and production method thereof |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114959448A (en) * | 2022-04-21 | 2022-08-30 | 中天钢铁集团有限公司 | Efficient production method of 1900 MPa-grade steel for suspension spring |
| CN114959448B (en) * | 2022-04-21 | 2023-03-10 | 中天钢铁集团有限公司 | Efficient production method of 1900 MPa-grade steel for suspension spring |
| CN115747645A (en) * | 2022-11-04 | 2023-03-07 | 马鞍山钢铁股份有限公司 | Steel for high-toughness high-contact-fatigue high-power wind power yaw bearing ring, bearing ring and production process |
| CN115927955A (en) * | 2022-11-04 | 2023-04-07 | 马鞍山钢铁股份有限公司 | Steel for high-homogenization high-power wind power yaw bearing ring, bearing ring and production process |
| CN115747645B (en) * | 2022-11-04 | 2024-04-30 | 马鞍山钢铁股份有限公司 | Steel for high-strength high-contact fatigue high-power wind power yaw bearing ring, bearing ring and production process |
| CN117230378A (en) * | 2023-11-10 | 2023-12-15 | 江苏沙钢集团淮钢特钢股份有限公司 | Steel for variable-section leaf springs of heavy-duty trucks and production process thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113930681B (en) | 2022-12-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113930681B (en) | High-hardenability high-fatigue-life low-temperature-resistant spring flat steel and production method thereof | |
| WO2020020066A1 (en) | Spring steel having superior fatigue life, and manufacturing method for same | |
| CN109161803B (en) | 1550 MPa-grade spring flat steel and production method thereof | |
| CN108118257B (en) | TiC particle reinforced ferrite/bainite based wear-resistant steel plate and manufacturing method thereof | |
| CN108220815B (en) | Hot work die steel with high heat resistance and high impact toughness for hot forging and preparation method thereof | |
| CN110629119B (en) | Spring flat steel and manufacturing process thereof | |
| CN111455269A (en) | Yield strength 960MPa grade very high strength marine steel plate and manufacturing method thereof | |
| CN102400039A (en) | Steel with good low-temperature toughness for slurry conveying pipeline and manufacturing method thereof | |
| CN113637915B (en) | Nb-Ti-B microalloyed carburized gear steel and preparation method thereof | |
| CN113403550B (en) | High-plasticity fatigue-resistant cold-rolled hot-galvanized DH1180 steel plate and preparation method thereof | |
| CN106191678A (en) | By the tensile strength of medium thin slab Direct Rolling >=1700MPa hot forming steel and production method | |
| CN109609845A (en) | A kind of 500MPa grades of weathering steel and its production method | |
| CN109097664B (en) | 900 MPa-grade thick-specification high-toughness hot-rolled steel strip and preparation method thereof | |
| CN113699437A (en) | Hot continuous rolling dual-phase wear-resistant steel for carriage plate and production method thereof | |
| CN110629003A (en) | Heat treatment-free hot continuous rolling ultrahigh-strength steel plate and manufacturing method thereof | |
| CN113652606B (en) | High-hardness high-toughness wear-resistant steel ball and preparation method thereof | |
| CN115679194B (en) | Plastic mold steel plate and manufacturing method thereof | |
| CN115558870A (en) | Economical long-life steel for high-power wind power yaw bearing ring, bearing ring and production process | |
| CN111876679B (en) | Chromium-vanadium hot-rolled steel wire rod and preparation method thereof, and preparation method of steel wire and hand tool | |
| CN115074643A (en) | Multi-process adaptive Q690 medium-thickness steel plate and production method thereof | |
| CN113584378A (en) | HB400 grade hot continuous rolling wear-resistant steel containing ferrite and production method thereof | |
| CN110055476B (en) | Low-phosphorus sulfur rare earth alloy steel for cold stamping type nut one-step forming die and preparation method thereof | |
| CN109881123B (en) | 1000 Mpa-grade high-strength metastable austenite-martensite stainless steel | |
| CN109023039B (en) | Anti-riot steel plate for 980 MPa-grade ATM and manufacturing method thereof | |
| CN111349850B (en) | High-corrosion-resistance weather-resistant steel and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |