CN111441005B - Free-cutting non-quenched and tempered steel and production method thereof - Google Patents
Free-cutting non-quenched and tempered steel and production method thereof Download PDFInfo
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- CN111441005B CN111441005B CN202010448931.3A CN202010448931A CN111441005B CN 111441005 B CN111441005 B CN 111441005B CN 202010448931 A CN202010448931 A CN 202010448931A CN 111441005 B CN111441005 B CN 111441005B
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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
- C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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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
- 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
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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
- 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
- C21D8/0226—Hot rolling
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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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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- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
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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
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
Abstract
The invention provides free-cutting non-quenched and tempered steel and a production method thereof, the free-cutting non-quenched and tempered steel is obtained by smelting, microalloying, secondary refining, casting, rolling and cooling, and the free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: contains C: 0.3-0.42%, Si: 0.41-0.55%, Mn: 1.2-1.45%, S: 0.03-0.055%, V: 0.06-0.10%, Ti: 0.016-0.020%, N: 0.010-0.016%, Al: 0-0.08%, Ca: 0.001-0.01%, Cu: 0.25-0.35 percent of the total weight of the elements; the balance being iron and other unavoidable impurities. The addition of elements such as Ti and Ca to steel can improve the workability during cutting.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to free-cutting non-quenched and tempered steel and a production method thereof.
Background
The non-quenched and tempered steel is mechanical structural steel which can meet the performance requirement without quenching and tempering, parts are manufactured by adopting the steel, quenching and tempering heat treatment procedures and equipment can be omitted, meanwhile, waste products generated in the heat treatment process are avoided, pollution is reduced, energy consumption is reduced, and the steel belongs to energy-saving steel.
With the rapid development of the automobile industry, indexes such as automobile safety, stability, energy consumption and the like require reliable, environment-friendly and weight-reduced automobile parts; meanwhile, the machining and manufacturing of automobile parts take a numerical control machine tool as a center, and higher requirements are put forward on the cutting performance of materials, so that the free-cutting non-quenched and tempered steel with high strength and toughness becomes the best choice of the automobile parts. The non-quenched and tempered steel for automobile crankshaft is made up by adding alloy elements to low-or medium-carbon manganese steel, fine-grain strengthening and toughening, and precipitation strengthening, and features high strength and toughness. The traditional free-cutting steel contains Pb element and has excellent processing performance, but the heavy metal element is harmful to the environment and is gradually eliminated along with the attention on environmental protection; the other is sulfur-containing free-cutting steel, which has improved machinability as the sulfur content increases, but too high a sulfur content causes hot shortness during rolling and forging. Therefore, a high-toughness non-heat-treated steel, which is a free-cutting steel containing no Pb and having excellent machinability, is desired.
The non-quenched and tempered steel is a novel energy-saving green structural material without quenching and tempering, has the performance and price ratio far superior to that of the traditional structural steel, is used for replacing the quenched and tempered steel, has the advantages of energy conservation, material conservation, simple process and the like, can reduce environmental pollution, and avoids oxidation, decarburization, deformation and cracking. The traditional process for producing the sulfur-containing free-cutting non-quenched and tempered steel in China comprises the following steps: electric furnace smelting, refining, die casting, controlled rolling and controlled cooling. The sulfur-containing free-cutting non-quenched and tempered steel produced by the method has poor purity, low yield and high production cost.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides free-cutting non-quenched and tempered steel and a production method thereof.
The present invention achieves the above-described object by the following technical means.
The free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: contains C: 0.3-0.42%, Si: 0.41-0.55%, Mn: 1.2-1.45%, S: 0.03-0.055%, V: 0.06-0.10%, Ti: 0.016-0.020%, N: 0.010-0.016%, Al: 0-0.08%, Ca: 0.001-0.01%, Cu: 0.25-0.35 percent of the total weight of the elements; the balance being iron and other unavoidable impurities. The addition of Ti element to steel can prevent the grain growth during austenite recrystallization, and has the function of refining grains. Further, the workability in cutting can be improved by Ca element.
Further, the free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.35-0.40%, Si: 0.40-0.49%, Mn: 1.3-1.4%, S: 0.04-0.05%, V: 0.07-0.085%, Ti: 0.016-0.017%, N: 0.012-0.014%, Al: 0-0.039%, Ca: 0.005-0.0076%, Cu: 0.28-0.30%, and the balance of iron and other inevitable impurities.
Further, the free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.36%, Si: 0.42%, Mn: 1.35%, S: 0.041%, V: 0.081%, Ti: 0.017%, N: 0.013%, Ca: 0.005%, Cu: 0.29%, and the balance of iron and other unavoidable impurities.
Further, the free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.38%, Si: 0.41%, Mn: 1.35%, S: 0.043%, V: 0.083%, Ti: 0.017%, N: 0.014%, Al: 0.008%, Ca: 0.0076%, Cu: 0.29 percent; the balance being iron and other unavoidable impurities.
A production method of free-cutting non-quenched and tempered steel comprises the following steps: smelting, microalloying, secondary refining, casting, rolling and cooling; in the rolling and cooling stages, respectively carrying out rough rolling and finish rolling on a hot strip mill, and carrying out hot rolling to obtain strip steel with a certain thickness, wherein the rough rolling heating temperature is 1160-1200 ℃, the initial rolling temperature is 1120-1160 ℃, and the final rolling temperature is 860-950 ℃; inputting the finish-rolled strip steel into a slow cooling furnace, and reducing the temperature to 120 ℃ after slow cooling; and then the mixture is conveyed from the cooling furnace to be cooled to room temperature.
Further, in the smelting stage, a heat storage heating furnace is used for smelting the blank, and the blank is heated to the required temperature in the heat storage heating furnace; and during tapping, blowing argon to the bottom of the ladle, adding a deoxidizing agent to realize pre-deoxidation, reacting the deoxidizing agent with oxygen in molten steel to generate a deoxidizing product insoluble in the molten steel, and removing slag from the molten steel to remove the deoxidizing product from the molten steel.
Further, in the secondary refining stage, molten steel with proper temperature, uniform components and good castability is obtained through the processes of heating in an LF furnace, blowing argon to the bottom of a steel ladle, blowing argon for stirring, slagging, deoxidizing, desulfurizing, secondary alloying and blowing argon for stirring.
Advantageous effects
1. According to the production method of the free-cutting non-quenched and tempered steel, the steps of smelting, micro-alloying, secondary refining, casting, rolling, cooling and the like are utilized, and the molten steel can be effectively deoxidized, alloyed and decontaminated by matching the two steps of rough refining and refining with an LF furnace in the production process of the free-cutting non-quenched and tempered steel.
2. In the preparation process of the free-cutting non-quenched and tempered steel, the Ti element is added into the steel to prevent the grain growth during austenite recrystallization and play a role in refining the grains. Further, the workability in cutting can be improved by Ca element.
Drawings
FIG. 1 is a production process diagram of the free-cutting non-quenched and tempered steel of the present invention.
Detailed Description
The invention will be further described with reference to the following figures and specific examples, but the scope of the invention is not limited thereto.
As shown in figure 1, the production process flow of the free-cutting non-quenched and tempered steel comprises the steps of smelting, alloying, secondary refining, casting, rolling and cooling in sequence,
in the smelting stage, a heat storage heating furnace is used for smelting the blank, and the blank is heated to the required temperature in the heat storage heating furnace; and during tapping, blowing argon to the bottom of the ladle, adding a deoxidizing agent to realize pre-deoxidation, reacting the deoxidizing agent with oxygen in molten steel to generate a deoxidizing product insoluble in the molten steel, and removing slag from the molten steel to remove the deoxidizing product from the molten steel. In the embodiment, the regenerative heating furnace takes blast furnace gas as fuel, and the calorific value of the gas is 800kcal/m3The heat value of the coal gas is low. Adopts air and coal gas double heat accumulating type burner.
In the secondary refining stage, the LF refining process is adopted to remove micro-impurities from the steel, and the specific process is as follows: heating an LF furnace, blowing argon to the bottom of a steel ladle, blowing argon for stirring, slagging, deoxidizing, desulfurizing, secondarily alloying and blowing argon for stirring; the molten steel with proper temperature, uniform components and good castability is obtained through the LF refining treatment.
In the casting stage, continuous casting is adopted to cast a casting blank, the temperature of a continuous casting tundish is controlled to be 25-40 ℃, the casting speed is controlled, and the continuous casting and drawing speed is 1.1m/min, so that the quality of the casting blank is ensured.
In the rolling and cooling stages, respectively carrying out rough rolling and finish rolling on a hot strip mill, and carrying out hot rolling to obtain strip steel with a certain thickness, wherein the rough rolling heating temperature is 1160-1200 ℃, the initial rolling temperature is 1120-1160 ℃, and the final rolling temperature is 860-950 ℃; inputting the finish-rolled strip steel into a slow cooling furnace, and reducing the temperature to 120 ℃ after slow cooling; and then the mixture is conveyed from the cooling furnace to be cooled to room temperature. Because high temperature is needed in hot rolling, after the hot rolled strip steel is slowly cooled from high temperature, the hot rolled steel is subjected to artificial aging treatment, and the residual stress of the strip steel can be quickly and fully eliminated at the stage.
By the production method of the free-cutting non-quenched and tempered steel, the deoxidized molten steel is added with the corresponding alloy, and alloying treatment is carried out to obtain the free-cutting non-quenched and tempered steel, wherein the mass percentages of the chemical elements of the obtained free-cutting non-quenched and tempered steel are as follows: contains C: 0.3-0.42%, Si: 0.41-0.55%, Mn: 1.2-1.45%, S: 0.03-0.055%, V: 0.06-0.10%, Ti: 0.016-0.020%, N: 0.010-0.016%, Al: 0-0.08%, Ca: 0.001-0.01%, Cu: 0.25-0.35%, by mass%; the balance being iron and other unavoidable impurities. The addition of Ti element to steel can prevent the grain growth during austenite recrystallization, and has the function of refining grains. Further, the workability in cutting can be improved by Ca element.
In example 1, the preferred free-cutting non-quenched and tempered steel chemical elements are, by mass: c: 0.3%, Si: 0.50%, Mn: 1.3%, S: 0.055%, V: 0.07%, Ti: 0.020%, N: 0.013%, Ca: 0.005%, Cu: 0.25%, and the balance of iron and other unavoidable impurities.
In example 2, the preferred free-cutting non-quenched and tempered steel chemical elements are, by mass: c: 0.38%, Si: 0.55%, Mn: 1.45%, S: 0.041%, V: 0.06%, Ti: 0.018%, N: 0.010%, Al: 0.039%, Ca: 0.001%, Cu: 0.35%, and the balance of iron and other unavoidable impurities.
In example 3, the preferred free-cutting non-quenched and tempered steel chemical elements are, by mass: c: 0.42%, Si: 0.41%, Mn: 1.2%, S: 0.03%, V: 0.10%, Ti: 0.016%, N: 0.016%, Al: 0.08%, Ca: 0.01%, Cu: 0.28 percent; the balance being iron and other unavoidable impurities.
The present invention is not limited to the above-described embodiments, and any obvious improvements, substitutions or modifications can be made by those skilled in the art without departing from the spirit of the present invention.
Claims (1)
1. A production method of free-cutting non-quenched and tempered steel comprises the following chemical elements in percentage by mass: c: 0.36%, Si: 0.42%, Mn: 1.35%, S: 0.041%, V: 0.081%, Ti: 0.017%, N: 0.013%, Ca: 0.005%, Cu: 0.29 percent, the balance of iron and other inevitable impurities, or the mass percent of the free-cutting non-quenched and tempered steel chemical elements is as follows: c: 0.38%, Si: 0.41%, Mn: 1.35%, S: 0.043%, V: 0.083%, Ti: 0.017%, N: 0.014%, Al: 0.008%, Ca: 0.0076%, Cu: 0.29 percent; the balance of iron and other unavoidable impurities; the method is characterized by comprising the following steps: smelting, microalloying, secondary refining, casting, rolling and cooling; in the rolling and cooling stages, respectively carrying out rough rolling and finish rolling on a hot strip mill, and carrying out hot rolling to obtain strip steel with a certain thickness, wherein the rough rolling heating temperature is 1160-1200 ℃, the initial rolling temperature is 1120-1160 ℃, and the final rolling temperature is 860-950 ℃; inputting the finish-rolled strip steel into a slow cooling furnace, and reducing the temperature to 120 ℃ after slow cooling; then cooling the mixture to room temperature from the cooling furnace;
in the smelting stage, a heat storage heating furnace is used for smelting the blank, and the blank is heated to the required temperature in the heat storage heating furnace; during tapping, argon is blown to the bottom of the steel ladle, a deoxidizing agent is added to realize pre-deoxidation, the deoxidizing agent reacts with oxygen in molten steel to generate a deoxidizing product which is insoluble in the molten steel, and the molten steel is subjected to deslagging to remove the deoxidizing product from the molten steel; in the secondary refining stage, molten steel with proper temperature, uniform components and good castability is obtained by sequentially heating in an LF furnace, blowing argon to the bottom of a steel ladle, stirring by blowing argon, slagging, deoxidizing, desulfurizing, secondarily alloying and stirring by blowing argon.
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| CN108779534A (en) * | 2016-03-16 | 2018-11-09 | 新日铁住金株式会社 | Micro Alloying bar steel |
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2020
- 2020-05-25 CN CN202010448931.3A patent/CN111441005B/en active Active
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| CN1667129A (en) * | 2004-03-10 | 2005-09-14 | 首钢总公司 | Method for producing sulfur free cutting and non-hardened and tempered steel |
| CN1861831A (en) * | 2006-06-13 | 2006-11-15 | 杭州钢铁集团公司 | 1100Mpa grade non modified high-strength steel and production process thereof |
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| CN109666856A (en) * | 2018-12-29 | 2019-04-23 | 江苏利淮钢铁有限公司 | A kind of high-strength tenacity semiaxis non-hardened and tempered steel and its production method instead of 42CrMo quenched and tempered steel |
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