CN112095051A

CN112095051A - Magnesium-calcium-tellurium composite treated free-cutting steel and preparation method and application thereof

Info

Publication number: CN112095051A
Application number: CN202011200292.5A
Authority: CN
Inventors: 宋朝琦; 杨树峰; 刘威; 李京社; 习小军; 赵梦静; 汪易航; 陈赛
Original assignee: University of Science and Technology Beijing USTB
Current assignee: Avic Jiuyuan Technology Beijing Co ltd
Priority date: 2020-11-02
Filing date: 2020-11-02
Publication date: 2020-12-18
Anticipated expiration: 2040-11-02
Also published as: CN112095051B

Abstract

The invention provides a magnesium-calcium-tellurium composite treated free-cutting steel, a preparation method and application thereof. The free-cutting steel treated by the magnesium-calcium-tellurium composite treatment comprises the following components in percentage by mass: 0.15 to 0.25 percent of C, 0.05 to 0.1 percent of Si, 1.2 to 2 percent of Mn1.2, 0.1 to 0.2 percent of S, 0.05 to 0.12 percent of P, 0.02 to 0.05 percent of Mg0.03 to 0.08 percent of Ca0.006 to 0.015 percent of Te0.and 97.185 to 98.394 percent of Fe97.185. The preparation method of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment comprises the following steps: and processing the raw materials of the free-cutting steel subjected to the magnesium-calcium-tellurium composite treatment to obtain the free-cutting steel subjected to the magnesium-calcium-tellurium composite treatment. The application of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment is used for processing parts. The application provides a magnesium-calcium-tellurium composite treated free-cutting steel, which increases cutting lubricity.

Description

Magnesium-calcium-tellurium composite treated free-cutting steel and preparation method and application thereof

Technical Field

The invention relates to the field of metallurgy, in particular to free-cutting steel subjected to magnesium-calcium-tellurium composite treatment, and a preparation method and application thereof.

Background

Free-cutting steel is a type of steel in which elements that make the steel brittle or have a lubricating effect are added to finally obtain free-cutting properties. The free-cutting property of the steel reduces the abrasion of a cutter in the machining process of the steel, reduces the cutting resistance so as to improve the machining efficiency and reduce the machining cost. The steel is widely applied to mechanical parts, precision instrument parts, automobile transmission shafts, machine tool parts, aerospace precision parts, electrical appliance parts and the like.

The existing free-cutting steel has the problems of uneven distribution of inclusions, severe reduction of the transverse mechanical property of the steel, reduction of the plasticity, toughness, fatigue strength and the like of the steel.

In view of this, the present application is specifically made.

Disclosure of Invention

The invention aims to provide a free-cutting steel subjected to magnesium-calcium-tellurium composite treatment, and a preparation method and application thereof, so as to solve the problems.

In order to achieve the above purpose, the invention adopts the following technical scheme:

a magnesium-calcium-tellurium composite treated free-cutting steel comprises the following components in percentage by mass:

0.15 to 0.25 percent of C, 0.05 to 0.1 percent of Si, 1.2 to 2 percent of Mn1.2, 0.1 to 0.2 percent of S, 0.05 to 0.12 percent of P, 0.02 to 0.05 percent of Mg0.03 to 0.08 percent of Ca0.006 to 0.015 percent of Te0.and 97.185 to 98.394 percent of Fe97.185.

Alternatively, the free-cutting steel treated by the Mg-Ca-Te complex treatment may have a C (carbon) content of 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25% or any value between 0.15% and 0.25%, a Si (silicon) content of 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1% or any value between 0.05% and 0.1%, a Mn (manganese) content of 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0% or any value between 1.2% and 2%, a S (sulfur) content of 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.0.0.0.0%, 2% or any value between 0.05% and 0.06%, a P (P) content of 0.05% or any value between 0.06%, 0%, 0.09%, or any value, 0.09%, 0.10%, 0.11%, 0.12%, and 0.05% -0.12%, the content of Mg (magnesium) may be any value between 0.02%, 0.03%, 0.04%, 0.05%, and 0.02% -0.05%, the content of Ca (calcium) may be any value between 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, and 0.03% -0.08%, the content of Te (tellurium) may be any value between 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.011%, 0.012%, 0.013%, 0.014%, 0.015%, and 0.006% -0.015%, the content of Fe (iron) may be any value between 97.185%, 97.2%, 97.3%, 97.4%, 97.5%, 97.6%, 97.7%, 97.8%, 97.9%, 97.98%, 0.98%, 98%, and 98.394%.

Preferably, in the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment, the mass ratio of manganese to sulfur is 12-15, the mass ratio of calcium to sulfur is 0.3-0.5, and the mass ratio of tellurium to sulfur is 0.06-0.09.

The quality ratio of manganese to sulfur, the quality ratio of calcium to sulfur and the quality ratio of tellurium to sulfur are controlled, so that the content of manganese sulfide and manganese telluride in a product is controlled, and the amount of a low-melting-point eutectic compound formed by the manganese telluride and the manganese sulfide is further controlled, so that the problem of overhigh melting point caused by overhigh content of magnesium is reduced, and the occurrence of water gap blockage in the casting process is indirectly reduced; the problem of uneven treatment of manganese sulfide caused by calcium evaporation is solved, and the problem of cutting performance reduction caused by increase of calcium sulfide is solved by wrapping the manganese telluride and the manganese sulfide.

Alternatively, in the magnesium-calcium-tellurium composite treated free-cutting steel, the mass ratio of manganese to sulfur may be any one of values between 12, 13, 14, 15 and 12 to 15, the mass ratio of calcium to sulfur may be any one of values between 0.3, 0.4, 0.5 and 0.3 to 0.5, and the mass ratio of tellurium to sulfur may be any one of values between 0.06, 0.07, 0.08, 0.09 and 0.06 to 0.09.

The preparation method of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment comprises the following steps of:

and processing the raw materials of the free-cutting steel subjected to the magnesium-calcium-tellurium composite treatment to obtain the free-cutting steel subjected to the magnesium-calcium-tellurium composite treatment.

Preferably, said processing comprises, in sequence:

smelting, ladle refining, continuous casting and steel rolling.

Preferably, the smelting adopts converter smelting or electric furnace smelting;

preferably, the smelting is preceded by pre-desiliconization and pre-dephosphorization;

preferably, oxygen blowing is adopted for decarburization in the smelting process;

preferably, a deoxidizer is added in the smelting tapping process for deoxidation;

preferably, the deoxidizer comprises a ferromanganese deoxidizer and/or a ferrosilicon deoxidizer;

preferably, the oxygen content in the alloy after deoxidation is from 100ppm to 300 ppm.

Since sulfur element belongs to beneficial elements in the magnesium-calcium-tellurium composite treated free-cutting steel provided by the application, only pre-desiliconization and pre-dephosphorization are carried out before smelting. Although phosphorus also contributes to machinability, too high a phosphorus content can cause cold shortness problems.

Alternatively, the oxygen content in the alloy after deoxidation may be any of 100ppm, 150ppm, 200ppm, 250ppm, 300ppm and between 100ppm and 300 ppm.

Preferably, the ladle refining is performed under reducing atmosphere conditions;

preferably, a sulfur wire, a calcium-magnesium alloy and a tellurium wire are added in the ladle refining process.

The adjustment of the contents of sulfur, calcium, magnesium and tellurium is realized by adding a sulfur wire, a calcium-magnesium alloy and a tellurium wire in the process of ladle refining.

Preferably, the cooling water amount of the continuous casting secondary cooling area is 0.2-0.3t water/t steel;

preferably, molten steel is stirred at the solidification end of the continuous casting;

preferably, the stirring is electromagnetic stirring.

The cooling speed is increased in the continuous casting process, so that the sulfur segregation can be reduced to the maximum extent. And the solidification end is stirred by an electromagnetic stirrer, so that the convection motion of molten steel is enhanced, the superheat degree is eliminated, the solidification structure of a casting blank is improved, and the segregation of sulfur elements is controlled.

Preferably, the cogging temperature of the rolled steel is 1300-1400 ℃, and the heat preservation time is 2-3 h;

preferably, the initial rolling temperature of the rolled steel is 1200-1250 ℃, and the final rolling temperature is 1000-1050 ℃;

preferably, after the steel rolling is finished, air cooling is adopted for cooling.

Optionally, the cogging temperature of the rolled steel can be any value between 1300 ℃, 1350 ℃, 1400 ℃ and 1300-1400 ℃, and the heat preservation time can be any value between 2h, 2.5h, 3h and 2-3 h; the initial rolling temperature of the rolled steel can be any value between 1200 ℃, 1210 ℃, 1220 ℃, 1230 ℃, 1240 ℃, 1250 ℃ and 1200-1250 ℃, and the final rolling temperature can be any value between 1000 ℃, 1010 ℃, 1020 ℃, 1030 ℃, 1040 ℃, 1050 ℃ and 1000-1050 ℃.

Preferably, the feedstock comprises sulphur-containing steel scrap.

The scrap steel with higher sulfur content is selected as part of raw materials, so that the cost of adding the sulfur line in the later period can be saved.

The application of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment is used for processing parts.

Compared with the prior art, the invention has the beneficial effects that:

according to the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment, the contents of magnesium, calcium and tellurium are controlled, so that the contents of manganese telluride and manganese sulfide and the contents of low-melting-point eutectic compounds formed by the manganese telluride and the manganese sulfide are controlled, the problem of overhigh melting point caused by overhigh magnesium content is weakened, and the occurrence of water gap blockage in the casting process is indirectly reduced; the problem of uneven treatment of manganese sulfide caused by calcium evaporation is solved, and the problem of cutting performance reduction caused by increase of calcium sulfide is solved by wrapping the manganese telluride and the manganese sulfide; the calcium and the magnesium are taken as deoxidizing elements and nucleation centers, so that the uniform distribution of the inclusions is facilitated, and the problem of poor dispersivity of the inclusions treated by tellurium is solved; the calcium and magnesium elements have a control effect on the form of manganese sulfide, and the addition amount of tellurium elements can be reduced, so that the production cost is reduced.

The preparation method of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment is simple in process and low in cost.

The application provides a magnesium calcium tellurium combined treatment's free-cutting steel, but wide application in precision parts processing, for example precision instrument part, automobile transmission shaft, lathe spare part, aerospace precision spare part, electric appliance part etc. field.

Drawings

To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of the present invention.

FIG. 1 is a macro distribution diagram of inclusions in Mg-Ca-Te composite treated free-cutting steel obtained in example 1;

FIG. 2 is a scanned image of typical inclusions in the Mg-Ca-Te composite treated free-cutting steel obtained in example 1;

FIG. 3 is a scanning electron microscope photograph of the steel material obtained in example 1;

FIG. 4 is a plot of manganese sulfide aspect ratio as a function of calcium to sulfur ratio;

FIG. 5 is a scanning electron micrograph of inclusions in a steel material obtained in comparative example 2;

FIG. 6 is a graph of the morphology of tellurium treated manganese sulfide at different locations in the Mg-Ca-Te composite treated free-cutting steel obtained in example 3;

FIG. 7 is a plot of manganese sulfide aspect ratio as a function of tellurium to sulfur ratio;

FIG. 8 is a morphological diagram of manganese sulfide without tellurium treatment at various positions in the steel obtained in comparative example 3.

Detailed Description

The terms as used herein:

"prepared from … …" is synonymous with "comprising". The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

The conjunction "consisting of … …" excludes any unspecified elements, steps or components. If used in a claim, the phrase is intended to claim as closed, meaning that it does not contain materials other than those described, except for the conventional impurities associated therewith. When the phrase "consisting of … …" appears in a clause of the subject matter of the claims rather than immediately after the subject matter, it defines only the elements described in the clause; other elements are not excluded from the claims as a whole.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when the range "1 ~ 5" is disclosed, the ranges described should be construed to include the ranges "1 ~ 4", "1 ~ 3", "1 ~ 2 and 4 ~ 5", "1 ~ 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

In these examples, the parts and percentages are by mass unless otherwise indicated.

"part by mass" means a basic unit of measure indicating a mass ratio of a plurality of components, and 1 part may represent any unit mass, for example, 1g or 2.689 g. If we say that the part by mass of the component A is a part by mass and the part by mass of the component B is B part by mass, the ratio of the part by mass of the component A to the part by mass of the component B is a: b. alternatively, the mass of the A component is aK and the mass of the B component is bK (K is an arbitrary number, and represents a multiple factor). It is unmistakable that, unlike the parts by mass, the sum of the parts by mass of all the components is not limited to 100 parts.

"and/or" is used to indicate that one or both of the illustrated conditions may occur, e.g., a and/or B includes (a and B) and (a or B).

Embodiments of the present invention will be described in detail below with reference to specific examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

The embodiment provides a magnesium-calcium-tellurium composite treated free-cutting steel, which comprises the following components in percentage by weight: 0.18%, Si: 0.06%, Mn: 1.4%, S: 0.1%, P: 0.07%, Mg: 0.03%, Ca: 0.04%, Te: 0.008% and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =14, ω [ Ca ]/ω [ S ] =0.4, and ω [ Te ]/ω [ S ] = 0.08.

The preparation method of the free-cutting steel subjected to magnesium-calcium-tellurium composite treatment comprises the following steps:

carrying out pre-desiliconization and pre-desulfurization on the molten iron from the blast furnace, and controlling the silicon content and the phosphorus content of the molten iron entering the converter; and decarburization is carried out by blowing oxygen in the process of smelting the molten iron in the converter, the residual carbon content is roughly predicted according to the brightness degree of flame, blowing is stopped, temperature measurement and sampling are carried out, the blowing supplementing time is determined, the carburetion method is avoided as much as possible, and the end point carbon content is controlled within the required range. And adding a ferromanganese deoxidizer and a ferrosilicon deoxidizer in the tapping process for deoxidation and alloying, wherein the oxygen content is controlled to be 150 ppm.

LF refining (ladle refining): on the premise of keeping reducing atmosphere, feeding a sulfur wire to adjust the sulfur content, adding a calcium-magnesium alloy, and then adding a pure tellurium cored wire. The bottom blowing argon gas speed control standard is that slag is not rolled.

Continuous casting: the sulfur content of the tundish covering slag is controlled, on the premise of ensuring no steel leakage, the cooling speed is increased to reduce sulfur segregation to the maximum extent, the secondary cooling zone is uniformly and quickly cooled by water cooling, the secondary cooling water content is controlled to be 0.25t water/t steel, an electromagnetic stirrer is used for stirring the solidification tail end, the convection motion of molten steel is enhanced, the degree of superheat is eliminated, the solidification structure of a casting blank is improved, and the segregation of sulfur elements is controlled.

Steel rolling: the soaking temperature before cogging is higher than 1300 ℃, the heat preservation time is 2.5 hours, the initial rolling temperature is 1220 ℃, the final rolling temperature is 1000 ℃, and an air cooling mechanism is adopted after rolling.

The macro distribution diagram of the inclusions of the magnesium-calcium-tellurium composite treated free-cutting steel obtained in example 1 is shown in fig. 1. FIG. 2 is a scanned image of typical inclusions in the Mg-Ca-Te composite treated free-cutting steel obtained in example 1.

Comparative example 1

The comparative example provides free-cutting steel, which comprises the following components in percentage by weight: 0.18%, Si: 0.06%, Mn: 1.4%, S: 0.1%, P: 0.07%, Ca: 0.04%, Te: 0.008% and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =14, ω [ Ca ]/ω [ S ] =0.4, and ω [ Te ]/ω [ S ] = 0.08.

The preparation method is the same as that of example 1.

And (3) comparative experiment analysis:

compared with the example 1, the magnesium element is lacked, and the morphology and distribution analysis of the inclusions in the product show that the finely dispersed magnesium oxide in the example 1 is used as the core of the heterogeneous nucleation of the manganese sulfide to promote the precipitation of the sulfide, so that the inclusions are distributed more uniformly and the machinability is better.

FIG. 3 is a scanning electron micrograph of the steel material obtained in example 1. As can be seen from FIG. 3, finely dispersed magnesium oxide serves as the core of the heterogeneous nucleation of manganese sulfide.

Example 2

The embodiment provides a magnesium-calcium-tellurium composite treated free-cutting steel, which comprises the following components in percentage by weight: 0.2%, Si: 0.08%, Mn: 1.5%, S: 0.12%, P: 0.07%, Mg: 0.04%, Ca: 0.06%, Te: 0.01 percent, and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =12.5, ω [ Ca ]/ω [ S ] =0.5, and ω [ Te ]/ω [ S ] = 0.083.

carrying out pre-desiliconization and pre-desulfurization on the molten iron from the blast furnace, and controlling the silicon content and the phosphorus content of the molten iron entering the converter; and decarburization is carried out by blowing oxygen in the process of smelting the molten iron in the converter, the residual carbon content is roughly predicted according to the brightness degree of flame, blowing is stopped, temperature measurement and sampling are carried out, the blowing supplementing time is determined, the carburetion method is avoided as much as possible, and the end point carbon content is controlled within the required range. And adding a ferromanganese deoxidizer and a ferrosilicon deoxidizer in the tapping process for deoxidation and alloying, wherein the oxygen content is controlled to be 200 ppm.

Continuous casting: the sulfur content of the tundish covering slag is controlled, on the premise of ensuring no steel leakage, the cooling speed is increased to reduce sulfur segregation to the maximum extent, the secondary cooling zone is uniformly and quickly cooled by water cooling, the secondary cooling water content is controlled to be 0.3t water/t steel, an electromagnetic stirrer is used for stirring the solidification tail end, the convection motion of molten steel is enhanced, the degree of superheat is eliminated, the solidification structure of a casting blank is improved, and the segregation of sulfur elements is controlled.

Steel rolling: the soaking temperature before cogging is higher than 1350 ℃, the heat preservation time is 2.6 hours, the initial rolling temperature is 1235 ℃, the final rolling temperature is 1050 ℃, and an air cooling mechanism is adopted after rolling.

Comparative example 2

The comparative example provides free-cutting steel, which comprises the following components in percentage by weight: 0.2%, Si: 0.08%, Mn: 1.5%, S: 0.12%, P: 0.07%, Mg: 0.04%, Ca: 0.2%, Te: 0.01 percent, and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =12.5, ω [ Ca ]/ω [ S ] =1.67, ω [ Te ]/ω [ S ] = 0.083.

The preparation method is the same as that of example 2.

And (3) comparative experiment analysis:

comparative example 2 has greatly increased elemental calcium content relative to example 2, resulting in the production of large amounts of calcium sulfide in the product of comparative example 2, the nozzle is prone to clogging, and the cutting performance is also reduced. The calcium treatment degree cannot be too low, and the inclusions are not changed into liquid phase due to insufficient calcium treatment, so that the effect of treating manganese sulfide is influenced, and the reduction of the cutting performance is further influenced. Fig. 4 is a curve of the change of the length-width ratio of manganese sulfide along with the calcium-sulfur ratio, after the calcium-sulfur ratio reaches a certain degree, the form of manganese sulfide cannot be particularly obviously affected by continuously increasing the calcium treatment, and on the contrary, the excessively large calcium-sulfur ratio can improve the generation of high-melting-point inclusion calcium sulfide, easily block a water gap and is not beneficial to the improvement of the cutting performance.

FIG. 5 is a scanning electron microscope photograph showing inclusions in the steel material obtained in comparative example 2. As can be seen from fig. 5, excessive calcium treatment causes the formation of calcium sulfide inclusions.

Example 3

The embodiment provides a magnesium-calcium-tellurium composite treated free-cutting steel, which comprises the following components in percentage by weight: 0.22%, Si: 0.09%, Mn: 2%, S: 0.16%, P: 0.09%, Mg: 0.05%, Ca: 0.06%, Te: 0.012%, and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =12.5, ω [ Ca ]/ω [ S ] =0.375, ω [ Te ]/ω [ S ] = 0.075.

carrying out pre-desiliconization and pre-desulfurization on the molten iron from the blast furnace, and controlling the silicon content and the phosphorus content of the molten iron entering the converter; and decarburization is carried out by blowing oxygen in the process of smelting the molten iron in the converter, the residual carbon content is roughly predicted according to the brightness degree of flame, blowing is stopped, temperature measurement and sampling are carried out, the blowing supplementing time is determined, the carburetion method is avoided as much as possible, and the end point carbon content is controlled within the required range. And adding a ferromanganese deoxidizer and a ferrosilicon deoxidizer in the tapping process for deoxidation and alloying, wherein the oxygen content is controlled at 220 ppm.

Steel rolling: the soaking temperature before cogging is higher than 1300 ℃, the heat preservation time is 2.5 hours, the initial rolling temperature is 1230 ℃, the final rolling temperature is 1000 ℃, and an air cooling mechanism is adopted after rolling.

FIG. 6 is a morphology chart of tellurium treated manganese sulfide at different positions in the Mg-Ca-Te composite treated free-cutting steel obtained in example 3.

Comparative example 3

The comparative example provides free-cutting steel, which comprises the following components in percentage by weight: 0.22%, Si: 0.09%, Mn: 2%, S: 0.16%, P: 0.09%, Mg: 0.05%, Ca: 0.06 percent, and the balance of Fe and inevitable impurity elements. Wherein ω [ Mn ]/ω [ S ] =12.5, and ω [ Ca ]/ω [ S ] = 0.375.

The preparation method is the same as example 3.

And (3) comparative experiment analysis:

comparative example 3 lacks tellurium element compared to example 3, manganese sulfide has a large length and width, and has too large deformability and reduced machinability. In example 3 after the tellurium treatment, spherical manganese sulfide and manganese telluride were uniformly distributed, the hardness of manganese sulfide was increased, the deformability during cutting was reduced, and the cutting performance was good. FIG. 7 is a plot of manganese sulfide aspect ratio as the tellurium-to-sulfur ratio increases. Therefore, the tellurium treatment has the function of spheroidizing manganese sulfide, and is beneficial to improving the cutting performance.

The free-cutting steel subjected to calcium-magnesium-tellurium composite treatment contains the eutectic of manganese telluride and manganese sulfide, so that the deformation of the manganese sulfide is limited, the cutting lubricity is increased, and the problem of uneven treatment of the manganese sulfide caused by calcium evaporation is solved; meanwhile, the package of the manganese telluride and the manganese sulfide solves the problem of cutting performance reduction caused by the increase of calcium sulfide, and the manganese telluride and the manganese sulfide form a low-melting-point eutectic so as to weaken the problem of overhigh melting point caused by overhigh magnesium content. The calcium and the magnesium can be used as deoxidizing elements and nucleation centers, are beneficial to the uniform distribution of inclusions, and solve the problem of poor dispersivity of the inclusions treated by tellurium. The calcium and the magnesium also have the function of controlling the form of manganese sulfide, so that the dosage of tellurium is reduced, and the production cost is further reduced.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. The free-cutting steel subjected to magnesium-calcium-tellurium composite treatment is characterized by comprising the following components in percentage by mass:

2. The magnesium-calcium-tellurium composite treated free-cutting steel as set forth in claim 1, wherein the magnesium-calcium-tellurium composite treated free-cutting steel has a manganese to sulfur mass ratio of 12 to 15, a calcium to sulfur mass ratio of 0.3 to 0.5, and a tellurium to sulfur mass ratio of 0.06 to 0.09.

3. A method for producing a mg-ca-te composite treated free-cutting steel as claimed in claim 1 or 2, comprising:

4. The method of claim 3, wherein the processing comprises, in sequence:

smelting, ladle refining, continuous casting and steel rolling.

5. The preparation method according to claim 4, wherein the smelting is converter smelting or electric furnace smelting;

6. The method of manufacturing according to claim 4, wherein the ladle refining is performed under reducing atmosphere conditions;

7. The manufacturing method according to claim 4, characterized in that the amount of cooling water in the secondary cooling zone of continuous casting is 0.2-0.3t water/t steel;

preferably, the stirring is electromagnetic stirring.

8. The preparation method according to claim 4, wherein the cogging temperature of the rolled steel is 1300-1400 ℃, and the holding time is 2-3 h;

9. The production method according to any one of claims 3 to 8, wherein the raw material comprises sulfur-containing scrap steel.

10. Use of a mg-ca-te composite treated free-cutting steel according to claim 1 or 2 for the machining of parts.