CN114058951A

CN114058951A - 65Mn saw blade steel and preparation method thereof

Info

Publication number: CN114058951A
Application number: CN202111218388.9A
Authority: CN
Inventors: 王畅; 于洋; 王林; 白凤霞; 郭子峰; 张亮亮; 高小丽; 刘文鑫; 于浩淼; 陈瑾; 焦会立
Original assignee: Shougang Group Co Ltd; Beijing Shougang Co Ltd
Current assignee: Shougang Group Co Ltd; Beijing Shougang Co Ltd
Priority date: 2021-10-19
Filing date: 2021-10-19
Publication date: 2022-02-18
Anticipated expiration: 2041-10-19
Also published as: CN114058951B

Abstract

The application relates to the technical field of steel rolling preparation, in particular to 65Mn saw blade steel and a preparation method thereof, wherein the saw blade steel comprises the following components: c, Si, Mn, Sb, Ni, and the balance of Fe and inevitable impurities thereof; the method comprises the following steps: obtaining molten steel containing the chemical components; continuously casting, hot rolling and coiling the molten steel to obtain saw blade steel; the hot rolling comprises heating before rolling, rough rolling and finish rolling; by adding Sb, Ni and Si elements into the steel grade and controlling the temperature of a continuous casting straightening section, a rough rolling fixed width section and a finish rolling large-pressure lower passage sub-section in the preparation method, the grain boundary of Sb is prevented from precipitating and embrittling austenite grain boundaries, and the tissues of a decarburized layer and the edge part are uniform, so that the mechanical properties of the decarburized layer and the edge part of the 65Mn saw blade steel on a conventional production line are uniformly distributed, and the condition of cracking does not exist.

Description

65Mn saw blade steel and preparation method thereof

Technical Field

The application relates to the technical field of steel rolling preparation, in particular to 65Mn saw blade steel and a preparation method thereof.

Background

The 65Mn saw blade steel is used for producing metal hot-cut circular saw blades, metal cold-cut circular saw blades, diamond saw blade matrixes and woodworking circular saw blades, the metal hot-cut circular saw blades produced by using 65Mn account for about 90% of the total amount of the metal hot-cut circular saw blades, and the metal hot-cut circular saw blades are suitable for the sawing operation of profiles and bars made of various materials such as plain carbon steel, alloy steel, bearing steel, high-speed steel and the like, the sawing temperature is generally over 750 ℃, and the high-alloy steel is over 800 ℃.

In the hot rolling production process of the present 65Mn saw blade steel, the phenomenon of decarburization on the surface layer of a steel grade is easy to occur due to lower carbon potential of the environment in a heating furnace and a rolling process, and the strength of the surface layer structure is reduced due to the decarburization phenomenon, so that the decarburized layer and the edge part of the steel are cracked, and the problems of reduction of the fatigue property of the steel and unqualified hardness of the steel are caused.

In view of the above problems, the current solutions are:

(1) the heating time is effectively shortened, and the depth of a decarburized layer is reduced;

(2) standardizing the spinning temperature;

(3) the atmosphere in the heat treatment furnace is adjusted to form a hydrogen-free protective atmosphere, so that the workpiece can be in a hydrogen-free environment in the heating and heat preservation processes of heat treatment, the carbon potential of the atmosphere is always equal to the carbon content of the workpiece in the furnace, and the workpiece can stay at high temperature for a long time without decarburization or recarburization.

However, because the difference between different production lines and equipment is large, and the three solutions only aim at specific equipment and production lines, and the feasibility of application in the conventional production line is lacked, how to solve the problem that the decarburized layer and the edge of the 65Mn saw blade steel are easy to crack on the conventional production line is a technical problem to be solved at present.

Disclosure of Invention

The application provides 65Mn saw blade steel and a preparation method thereof, which aim to solve the technical problems that a decarburized layer and the edge of the 65Mn saw blade steel on a conventional production line are easy to crack in the prior art.

In a first aspect, the present application provides a 65Mn saw blade steel, comprising, in mass fraction: c: 0.65% -0.75%, Si: 0.3% -0.4%, Mn: 1.1% -1.2%, Sb: 0.01-0.03%, Ni: 0.05 to 0.01 percent, and the balance of Fe and inevitable impurities.

Optionally, the metallographic structure of the saw blade steel includes, in terms of volume fraction: ferrite is less than or equal to 5 percent, and pearlite is more than or equal to 95 percent.

Optionally, the total decarburization depth of the saw blade steel is 5-15 μm.

In a second aspect, the present application provides a method of manufacturing a 65Mn saw blade steel, the method comprising:

obtaining molten steel containing the chemical components;

continuously casting, hot rolling and coiling the molten steel to obtain saw blade steel;

the hot rolling comprises heating before rolling, rough rolling and finish rolling;

the continuous casting comprises a straightening section, and the temperature of the straightening section is more than or equal to 950 ℃;

the rough rolling comprises a constant width section, and the temperature of the constant width section is 1100-1180 ℃;

the finish rolling comprises a high-pressure descending sub-section, and the temperature of the high-pressure descending sub-section is 1000-1050 ℃; (ii) a

The coiling comprises the following steps: and coiling in a front-section cooling mode, wherein the coiling temperature is 620-660 ℃.

Optionally, the end point temperature of the heating before rolling is 1200-1220 ℃, and the time is 140-160 min.

Optionally, the heating before rolling comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, the air excess coefficient of the weak oxidation atmosphere is 1.1-1.2, and the oxygen content of the weak oxidation atmosphere is 0.01-0.03%;

the temperature of the soaking section is 1200-1220 ℃, and the time is 30-40 min.

Optionally, the rough rolling further includes: carrying out rough rolling by adopting a 1+ 5-pass rolling mode, and carrying out side phosphorus removal after rough rolling;

the 1+ 5-pass rolling mode comprises the following steps: roughly removing phosphorus before rolling, and then starting the first pass of R1 and the first pass, the third pass, the fourth pass and the fifth pass of R2 for rolling;

the pressure of the side dephosphorization is 15 MPa-20 MPa.

Optionally, the side width reduction amount of the first pass of the R2 is less than or equal to 15mm, the side width reduction amount of the third pass of the R2 is less than or equal to 10mm, and the side width reduction amount of the fifth pass of the R2 is less than or equal to 5 mm.

Optionally, the inlet temperature of the finish rolling is 1030-1060 ℃, the finishing temperature is 850-880 ℃, and the rolling speed is more than or equal to 9 m/s.

Optionally, the pulling speed of the straightening section is 1.4 m/min-1.6 m/min; the width adjustment amount of the edge part of the fixed width section is less than or equal to 50 mm.

Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:

according to the 65Mn saw blade steel and the preparation method thereof provided by the embodiment of the application, Sb, Ni and Si elements are added into steel, a moving passage of oxygen ions and carbon ions is blocked by Sb, Ni is favorable for improving the solubility of the Sb elements in the steel and improving the melting point of a eutectic product, Si can reduce the surface hot brittleness sensitivity and is favorable for reducing the growth speed of cracks, and then the temperature of a continuous casting straightening section, a rough rolling constant width section and a finish rolling sub-section in the preparation method is controlled to avoid the precipitation of an embrittlement austenite crystal boundary from the crystal boundary of Sb, so that the tissues of a decarburized layer and the edge part are uniform, the distribution of the mechanical properties of the decarburized layer and the edge part of the 65Mn saw blade steel on a conventional production line is uniform, and the condition of cracking does not exist.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

FIG. 1 is a schematic flow chart of a method for manufacturing 65Mn saw blade steel according to an embodiment of the present application;

FIG. 2 is a schematic view of a decarburized layer without Sb element added to a 65Mn saw blade steel according to an embodiment of the present invention;

FIG. 3 is a schematic view of a decarburized layer of 65Mn saw blade steel to which Sb is added according to an embodiment of the present invention;

FIG. 4 is a schematic view of an edge crack caused by adding too much Sb element into a 65Mn saw blade steel according to an embodiment of the present disclosure;

FIG. 5 is a schematic view of the enrichment of the surface layer of Sb element added to 65Mn saw blade steel according to an embodiment of the present disclosure;

FIG. 6 is a schematic view of the enrichment of the surface layer of Sb element added to 65Mn saw blade steel according to the embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In one embodiment of the present application, there is provided a 65Mn blade steel, comprising, in mass fraction: c: 0.65% -0.75%, Si: 0.3% -0.4%, Mn: 1.1% -1.2%, Sb: 0.01-0.03%, Ni: 0.05 to 0.01 percent, and the balance of Fe and inevitable impurities.

In the application, the positive effect that the mass fraction of C is 0.65-0.75% is that the movement of C is hindered, and the depth of a decarburized layer is reduced; c is a main source of strength and hardness of the alloy, when the mass fraction is too large, the adverse effect is that the C content is too high, the martensite transformation temperature and the carbide proportion in the heat treatment process are influenced, and the final surface hardness is influenced, and when the mass fraction is too small, the adverse effect is that the C content is insufficient, the surface hardness is influenced, and the surface hardness is insufficient.

The active effect that the mass fraction of Si is 0.3-0.4% is that the number of Sb-rich phases at the interface between the iron scale and the steel matrix is reduced, which is beneficial to reducing the surface hot brittleness sensitivity, and simultaneously, the Si can also reduce the growth speed of cracks, thereby reducing the permeation of the Sb-rich phases and ensuring that edges are not cracked; when the value range of the mass fraction is too large, the adverse effect is that the adhesion of the iron skin is too strong in the hot rolling process, descaling is not easy, and the surface quality of the steel plate is reduced.

The positive effect that the mass fraction of Mn is 1.1-1.2% is that Mn can improve the hardenability of steel within the mass fraction range; when the value range of the mass fraction is too large, the adverse effect is that not only the cost of steel is increased, but also the excessive Mn is easy to cause serious banding of the product and is not beneficial to the performance uniformity of the finished product, and when the value range of the mass fraction is too small, the adverse effect is that the Mn content is too low, the hardenability is insufficient and the formation of martensite in the heat treatment process is not beneficial.

The positive effect that the mass fraction of Sb is 0.01-0.03% is that a decarburizing layer can be effectively inhibited, the Sb element is added to block the moving path of oxygen ions and carbon, and the Sb element has the tendency of surface layer and grain boundary enrichment in the heating and rolling processes, so that the decarburizing phenomenon in the heating and rolling processes before rolling can be reduced; when the mass fraction is too large, the adverse effect is that the Sb content is too high, the Sb element can be aggregated in a molten steel matrix under the formed iron scale, and when the mass fraction exceeds a dissolution limit, a molten liquid phase can be formed, so that the surface of a steel plate is subjected to a 'hot brittleness' phenomenon.

The positive effect that the mass fraction of Ni is 0.05-0.01% is that a molten liquid phase is formed on an interface between an iron scale and a steel matrix because the oxidation potential energy of Sb is lower than that of iron and is not oxidized, and the addition of Ni is beneficial to improving the solubility of Sb in steel and the melting point of an eutectic product, so that the Sb is uniformly distributed, the uniformity of a decarburized layer is ensured, and the cracking condition is prevented; when the value range of the mass fraction is too large, the adverse effect is that the cost of the steel grade is greatly increased due to excessive Ni, and the Ni element does not participate in oxidation reaction, so that the Ni element is enriched on the surface layer, the iron sheet stickiness phenomenon occurs in the hot rolling process, and the removability of the steel is deteriorated.

As an alternative embodiment, the metallographic structure of the saw blade steel comprises, in volume fraction: ferrite is less than or equal to 5 percent, and pearlite is more than or equal to 95 percent.

In the application, the positive effect that the ferrite is less than or equal to 5 percent is that the ferrite can ensure the hardness range of the surface layer after quenching; when the volume fraction is excessively large, there is a negative effect that the hardness of the surface layer after heat treatment is lowered by excessive ferrite.

As an alternative embodiment, the saw blade steel has a total decarburized layer depth of 5 μm to 15 μm.

In one embodiment of the present application, as shown in fig. 1, there is provided a method of manufacturing a 65Mn saw blade steel, the method comprising:

s1, obtaining molten steel containing the chemical components;

s2, continuously casting, hot rolling and coiling the molten steel to obtain saw blade steel;

the finish rolling comprises a high-pressure descending sub-section, and the temperature of the high-pressure descending sub-section is 1000-1050 ℃.

In the application, the positive effect that the temperature of the straightening section is more than or equal to 950 ℃ is to avoid the interval from the temperature of Sb element precipitation in the continuous casting and cooling process to the nose tip temperature; when the temperature range is too small, the adverse effect is that the temperature is too low, and after grains are refined, the grain boundary segregation capacity of the Sb element is enhanced, so that the surface layer cracking condition in the continuous casting process is easy to occur.

The temperature of the constant-width section is 1100-1180 ℃, and the positive effect is that under the condition of the temperature range, namely large deformation is carried out in the austenite dynamic recrystallization temperature range, the recovery of the structure is facilitated, and the occurrence of edge cracking in the hot rolling process is inhibited; when the temperature value range is too large, the adverse effect to be caused is that the control of the tapping temperature in the hot rolling process is not facilitated, the temperature of the heating furnace is too high, the decarburized layer of the steel grade is increased, and when the temperature value range is too small, the adverse effect to be caused is that the temperature is too low, the decarburized layer falls into an austenite dynamic unrecrystallized area, and the recovery of the edge defects in the hot rolling process is not facilitated.

The temperature of the high-pressure lower section is 1000-1050 ℃, so that the nose tip temperature at the liquefaction melting point temperature of the Sb element can be avoided; when the temperature value range is too large, the adverse effect to be caused is that the finish rolling inlet temperature in the hot rolling process is too high, the depth of a total decarburized layer is not easy to control, the depth of the total decarburized layer of steel is uneven, when the temperature value range is too small, the adverse effect to be caused is that the temperature of the edge part in the hot rolling process is too low, the edge part is easy to fall into a two-phase region for rolling, and intergranular cracking is caused.

The positive effect that the coiling temperature is 620-660 ℃ is that the surface of the steel plate can be subjected to full decarburization when the high-carbon steel is subjected to heat preservation in a two-phase region, and the steel plate is characterized in that ferrite grains stretch along the direction vertical to the surface of a sample and have strong directionality, and the specific principle is as follows: when the steel plate is heated in a two-phase region, the steel structure is untransformed pro-eutectoid ferrite + austenite (A1-A3) or full austenite (A3-A1), the carbon content in the austenite is reduced along with the progress of decarburization, the equilibrium state is broken when the carbon content is lower than the carbon content C0 in the austenite in the equilibrium state, the austenite must precipitate ferrite in order to reach the carbon content C0 in the equilibrium state again, the precipitated ferrite preferentially grows on the surface along the untransformed ferrite or the ferrite precipitated first in the original structure, and the ferrite gradually increases along the progress of decarburization to form a fully decarburized structure with uniform depth; when the temperature value range is too large, the unfavorable influence caused by the excessively high temperature can cause decarburization reaction in the coiling process, and the control of a final decarburized layer is not facilitated.

As an optional embodiment, the end point temperature of the heating before rolling is 1200-1220 ℃, and the time is 140-160 min.

In the application, the positive effect that the end point temperature of heating before rolling is 1200-1220 ℃ is that the analysis of the decarburization phenomenon of the high-carbon steel shows that the peak of the total decarburization depth can be reached when the high-carbon steel is heated to 1100-1200 ℃ before rolling, and the oxidation speed of the steel grade is higher than the decarburization speed along with the rise of the temperature, so that the total decarburization depth has a descending trend along with the rise of the temperature; when the temperature value range is too large, the adverse effect caused by the overhigh temperature cannot be used for effectively utilizing the balance of oxidation and decarburization, so that the heating before rolling cannot reach the optimal control stage of the heating process decarburized layer.

The positive effect that the heating time before rolling is 140-160 min is that the total surface decarburization depth in the heating process can be controlled in the time range; when the time value range is too large, the adverse effect to be caused is overlong heating temperature before rolling, the oxidation is caused to show a parabolic growth trend, if the oxidation rate is slowed down in the oxidation time process, the surface decarburization is higher than the oxidation speed, the optimal control of a decarburized layer is not facilitated, and when the time value range is too small, the adverse effect to be caused is that the steel plate can not be effectively burnt through, so that the uniformity of the internal temperature of the steel plate can not be ensured.

As an optional embodiment, the pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, the air excess coefficient of the weak oxidation atmosphere is 1.1-1.2, and the oxygen content of the weak oxidation atmosphere is 0.01% -0.03%;

In the application, the positive effect that the air excess coefficient of the weak oxidizing atmosphere is 1.1-1.2 is that the weak oxidizing atmosphere in the soaking section is beneficial to forming a certain thickness of iron scale on the surface of the steel, and the addition of the Si element can promote the oxidizing reaction of the soaking section, so that the overall depth of the decarburized layer in the soaking section is further weakened.

The oxygen content of the weak oxidation atmosphere is 0.01-0.03 percent, and the positive effect is that; when the value range of the oxygen content is too large, the adverse effect is that the excessive oxygen content inverts the surface oxidation to seriously form a thicker iron scale, the burning loss is increased, the over-thick structure of the iron scale is compact, the volatilization of Sb element is not facilitated, and when the value range of the oxygen content is too small, the adverse effect is that the oxygen content is too low, the field control difficulty is increased, and the stability of the atmosphere in the heating furnace cannot be ensured.

The positive effect that the temperature of the soaking section is 1200-1220 ℃ is that the decarburization phenomenon analysis of high-carbon steel shows that the peak of the total decarburization depth can be reached when the high-carbon steel is heated to 1100-1200 ℃ before rolling, and the oxidation speed of steel is greater than the decarburization speed along with the rise of temperature, so that the total decarburization depth has a descending trend along with the rise of temperature; when the temperature value range is too large, the adverse effect to be caused is that the too high temperature can not effectively control the decarburized layer in the hot rolling process, the decarburizing rate is greater than the oxidation rate, the total decarburized layer depth is increased, when the temperature value range is too small, the adverse effect to be caused is that the too low temperature can enable the oxidation rate to be less than the decarburizing rate, the surface decarburized layer can not be effectively removed by utilizing the heating process, and the total decarburizing layer depth is increased.

The time of the soaking section is 30-40 min, and the positive effect is that the time range is favorable for ensuring that the depth of the total decarburized layer is in a small range; when the time value range is too large, the adverse effect to be caused is that the time of the soaking period is too long, so that the oxidation speed is less than the speed, the decarburized layer cannot be consumed through the heating process, so that the depth of the total decarburized layer is too large, and when the time value range is too small, the adverse effect to be caused is that the time of the soaking period is too short, so that the decarburized layer cannot be effectively eliminated, and the depth of the total decarburized layer is too large.

As an optional embodiment, the rough rolling further comprises: carrying out rough rolling by adopting a 1+ 5-pass rolling mode, and carrying out side phosphorus removal after rough rolling;

the pressure of the side dephosphorization is 15 MPa-20 MPa.

In the application, the positive effect of adopting the 1+5 pass rolling mode for rough rolling is favorable for the temperature stability control in the hot rolling process.

The positive effect that the pressure of the side dephosphorization is 15 MPa-20 MPa is that the surface layer enrichment layer of the furnace side of the raw Sb element can be effectively removed; when the value range of the pressure is too large, the adverse effect is that the excessive pressure causes unstable pressure of other descaling systems, and when the value range of the pressure is too small, the adverse effect is that the too small pressure cannot effectively remove the Sb element furnace-generated enrichment layer.

As an optional embodiment, the side portion reducing amount of the first pass of the R2 is less than or equal to 15mm, the side portion reducing amount of the third pass of the R2 is less than or equal to 10mm, and the side portion reducing amount of the fifth pass of the R2 is less than or equal to 5 mm.

In the application, the positive effect that the side width reduction amount of the first pass of R2 is less than or equal to 15mm is to avoid the occurrence of cracking in the rolling process; when the value range of the edge widening amount is too large, the adverse effect is that the grain boundary deformation capability in the rolling process is insufficient due to too large deformation amount in the rolling process, so that the edge cracking condition is caused.

The positive effect that the side width reduction amount of the third pass of R2 is less than or equal to 10mm is to avoid the occurrence of cracking in the rolling process; when the value range of the edge widening amount is too large, the adverse effect is that the deformation amount in the rolling process is too large, the crystal boundary deformation capacity in the rolling process is easy to be insufficient, and the edge cracking condition is caused.

The positive effect that the edge width reduction amount of the fifth pass of R2 is less than or equal to 5mm is to avoid the occurrence of cracking in the rolling process; when the value range of the edge width reduction is too large, the adverse effect is that the deformation in the rolling process is too large, the crystal boundary deformation capability in the rolling process is easy to be insufficient, the edge cracking condition is caused, and the width reduction is properly reduced along with the reduction of the edge temperature.

As an optional embodiment, the inlet temperature of the finish rolling is 1030-1060 ℃, the finishing temperature is 850-880 ℃, and the rolling speed is more than or equal to 9 m/s.

In the application, the positive effect that the inlet temperature of finish rolling is 1030-1060 ℃ is that effective descaling can be carried out above the phase melting point temperature of Sb element in the temperature range, so that the surface grain boundary in the finish rolling process of enrichment layer embrittlement is inhibited; when the temperature value range is too large, the adverse effect is that the temperature is too high, the surface layer enrichment trend is easy to occur in the finish rolling process, and when the temperature value range is too small, the adverse effect is that the hardness of the hot rolling process is too large, the rolling is difficult, the finish rolling temperature cannot be effectively ensured, and the temperature of the edge of the steel plate does not fall into the temperature range of the two-phase region.

The positive effect that the finishing temperature is 850-880 ℃ is that the hot rolling process can be prevented from falling into a two-phase region for rolling in the temperature range; when the temperature value range is too large, the adverse effect is that the depth of a total decarburized layer on the surface layer in the finish rolling process is increased due to too high temperature, and when the temperature value range is too small, the adverse effect is that the rolling difficulty is brought due to too low temperature and the cracking problem is caused due to the fact that the edge part falls into a two-phase region for rolling.

The positive effects of the rolling speed of more than or equal to 9m/s are low-temperature and rapid rolling, the C-O reaction time in the finish rolling process is reduced, and the total decarburization depth is reduced; when the rolling speed is too small, the decarburized layer in the finish rolling process is increased.

As an alternative embodiment, the pulling speed of the straightening section is 1.4m/min to 1.6 m/min; the width adjustment amount of the edge part of the fixed width section is less than or equal to 50 mm.

In the application, the positive effect that the pulling speed of the straightening section is 1.4 m/min-1.6 m/min is that the temperature interval of the straightening section can be effectively avoided; when the value range of the drawing speed is too large, the problem of bleed-out is caused because the drawing speed is too large and the formation of a billet shell is not facilitated, and when the value range of the drawing speed is too small, the problem of surface layer cracking and the like in the continuous casting process because a straightening section falls near the nose tip temperature of an Sb-phase embrittlement crystal boundary is caused.

The positive effect that the adjustment quantity of the edge width of the fixed-width section is less than or equal to 50mm is that the Sb element is enriched, and the temperature, the broadening, the deformation and the difference between the middle part and the temperature, the broadening and the deformation of the edge part are different, so that the cracking in the rolling process caused by the fact that the Sb element falls into a high-temperature brittle section is avoided; when the value range of the edge width adjustment amount is too small, the adverse effect is that the width specification requirement of the user cannot be accurately met.

Example 1

A65 Mn saw blade steel, comprising, in mass fractions: c: 0.67%, Si: 0.35%, Mn: 1.15%, Sb: 0.02%, Ni: 0.04% and the balance of Fe and inevitable impurities.

A method of making a 65Mn saw blade steel, the method comprising:

s1, obtaining molten steel containing the chemical components;

the rough rolling comprises a fixed width section, the temperature of the fixed width section is 1170 ℃, and the width adjustment amount of the edge part of the fixed width section is less than or equal to 50 mm;

the finish rolling comprises a large-pressure descending sub-section, and the temperature of the large-pressure descending sub-section is 1040 ℃.

The end point temperature of the heating before rolling is 1200 ℃, and the time is 150 min.

The pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, the air excess coefficient of the weak oxidation atmosphere is 1.2, and the oxygen content of the weak oxidation atmosphere is 0.03%;

the temperature of the soaking section is 1200 ℃, and the time is 35 min.

The rough rolling further comprises: carrying out rough rolling by adopting a 1+ 5-pass rolling mode, and carrying out side phosphorus removal after rough rolling;

the pressure of the side dephosphorization is 19 MPa.

The side width reducing amount of the first pass of the R2 is less than or equal to 15mm, the side width reducing amount of the third pass of the R2 is less than or equal to 10mm, and the side width reducing amount of the fifth pass of the R2 is less than or equal to 5 mm.

The inlet temperature of the finish rolling is 1030-1060 ℃, the finishing temperature is 880 ℃, and the rolling speed is more than or equal to 9 m/s.

The coiling comprises the following steps: coiling is carried out by adopting a front-stage cooling mode, and the coiling temperature is 650 ℃.

Example 2

Example 2 is compared to example 1, with example 2 differing from example 1 in that:

a65 Mn saw blade steel, comprising, in mass fractions: c: 0.65%%, Si: 0.3%, Mn: 1.1%, Sb: 0.01%, Ni: 0.05%, and the balance of Fe and inevitable impurities.

the rough rolling comprises a fixed width section, the temperature of the fixed width section is 1165 ℃, and the adjustment quantity of the edge width of the fixed width section is less than or equal to 50 mm;

the finish rolling comprises a large-pressure descending sub-section, and the temperature of the large-pressure descending sub-section is 1050 ℃.

The end point temperature of the heating before rolling is 1200 ℃, and the time is 140 min.

The pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, the air excess coefficient of the weak oxidation atmosphere is 1.1, and the oxygen content of the weak oxidation atmosphere is 0.01%;

the temperature of the soaking section is 1200 ℃, and the time is 30 min.

The pressure of the edge phosphorus removal is 15MPa

The inlet temperature of the finish rolling is 1030 ℃, and the finish rolling temperature is 880 ℃.

The coiling comprises the following steps: coiling is carried out by adopting a front-stage cooling mode, and the coiling temperature is 620 ℃.

Example 3

Example 3 is compared to example 1, with example 3 differing from example 1 in that:

a65 Mn saw blade steel, comprising, in mass fractions: c: 0.75%, Si: 0.4%, Mn: 1.2%, Sb: 0.03%, Ni: 0.01 percent, and the balance of Fe and inevitable impurities.

the rough rolling comprises a fixed width section, the temperature of the fixed width section is 1150 ℃, and the adjustment quantity of the edge width of the fixed width section is less than or equal to 50 mm;

the finish rolling comprises a large-pressure descending sub-section, and the temperature of the large-pressure descending sub-section is 1020 ℃.

The end point temperature of the heating before rolling is 1220 ℃, and the time is 160 min.

The pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, the air excess coefficient of the weak oxidation atmosphere is 1.2, and the oxygen content of the weak oxidation atmosphere is 0.02%;

the temperature of the soaking section is 1220 ℃, and the time is 40 min.

The pressure of the side phosphorus removal is 20MPa

The inlet temperature of the finish rolling is 1060 ℃, and the finish rolling temperature is 870 ℃.

The coiling comprises the following steps: and coiling in a front-stage cooling mode, wherein the coiling temperature is 660 ℃.

Example 4

Example 4 is compared to example 1, with example 4 differing from example 1 in that:

The pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, and the air excess coefficient of the weak oxidation atmosphere is 1.2;

the temperature of the soaking section is 1220 ℃, and the time is 40 min.

The pressure of the side phosphorus removal is 20MPa

The inlet temperature of the finish rolling is 1060 ℃, and the finishing temperature is 860 ℃.

Example 5

Example 5 is compared to example 1, with example 5 differing from example 1 in that:

the rough rolling comprises a fixed width section, the temperature of the fixed width section is 1140 ℃, and the width adjustment quantity of the edge part of the fixed width section is less than or equal to 50 mm;

the temperature of the soaking section is 1200 ℃, and the time is 30 min.

The pressure of the edge phosphorus removal is 15MPa

The inlet temperature of the finish rolling is 1030 ℃, and the finishing temperature is 850 ℃.

Comparative example 1

Comparative example 1 and example 1 were compared, and comparative example 1 and example 1 were distinguished in that:

a65 Mn saw blade steel, comprising, in mass fractions: c: 0.65%, Si: 0.35%, Mn: 1.1%, Ni: 0.01 percent, and the balance of Fe and inevitable impurities.

Comparative example 2

Comparative example 2 is compared with example 1, and comparative example 2 differs from example 1 in that:

a65 Mn saw blade steel, comprising, in mass fractions: 0.65% of C, Si: 0.35%, Mn: 1.1%, Sb: 0.005%, Ni: 0.005% and the balance of Fe and inevitable impurities.

Comparative example 3

Comparative example 3 is compared with example 1, and comparative example 3 differs from example 1 in that:

the rough rolling comprises a fixed width section, and the temperature of the fixed width section is 1050-1100 ℃;

the finish rolling comprises a large-pressure descending sub-section, and the temperature of the large-pressure descending sub-section is 980 ℃.

Comparative example 4

Comparative example 4 is compared with example 1, and comparative example 4 differs from example 1 in that:

the end point temperature of the heating before rolling is 1250 ℃, and the time is 200 min.

The pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weak oxidation atmosphere, and the air excess coefficient of the weak oxidation atmosphere is 1.1.

Comparative example 5

Comparative example 5 is compared with example 1, and comparative example 5 differs from example 1 in that:

the temperature of the soaking section is 1180 ℃ and the time is 60 min.

Comparative example 6

Comparative example 6 is compared with example 1, and comparative example 6 differs from example 1 in that:

the pressure of the side dephosphorization is 12 MPa.

The inlet temperature of the finish rolling is 1080 ℃ and the finish rolling temperature is 900 ℃.

Comparative example 7

Comparative example 7 is compared with example 1, and comparative example 7 differs from example 1 in that:

the coiling comprises the following steps: coiling is carried out by adopting a front-stage cooling mode, and the coiling temperature is 700 ℃.

Related experiments:

saw blade steels obtained in examples 1 to 5 and comparative examples 1 to 7 were collected, and the properties of each saw blade steel were measured, and the results are shown in table 1.

Test method of related experiment

The method for testing the total decarburized layer depth comprises the following steps: the national standard GB/T224-2008 'depth determination method for decarburized layer of steel', wherein the depth determination method for decarburized layer in the standard can be divided into three methods, namely a metallographic method, a hardness method and a chemical analysis method. In the application, a metallographic method is adopted for detection; determination of the total decarburized layer:

in medium-carbon steel and low-alloy steel, which are distinguished by the relative quantitative change of ferrite with respect to the other structure constituents, the distance from the surface to the point at which the structure and the base structure are indistinguishable is measured by means of a micrometer eye lens or directly on a microscope frosted glass screen. Several measurements (at least 5 times) were randomly carried out for each sample in a visual field of the deepest uniform decarburization region, and the average of these measurements was taken as the total decarburization depth.

TABLE 1

Specific analysis of table 1:

from the data of examples 1-5, it can be seen that:

through the addition of the alloy element in the application, the depth of a total decarburized layer is favorably reduced, and the edge crack defect can be avoided by matching with the optimization of a heating process and the adjustment of the width of a hot-rolled edge.

From the data of comparative examples 1 to 7:

the addition of less Sb element is not beneficial to inhibiting the diffusion of C element, so that the integral decarburization depth is increased, meanwhile, the Ni element is not enough in proportion, the melting point is low, the influence of grain boundary segregation and embrittlement is easy to occur, and the problem of edge cracking at multiple positions in the hot rolling process is caused.

One or more technical solutions in the embodiments of the present application at least have the following technical effects or advantages:

(1) the average depth of the decarburized layer of the hot-rolled finished product of the saw blade steel prepared by the method is 15 mu m, the depth of the decarburized layer is uniform, the mechanical property of the whole saw blade steel is excellent, and the metallographic structure is uniform, wherein the volume fraction of ferrite is less than or equal to 5%, and the volume fraction of pearlite is more than or equal to 95%.

(2) According to the preparation method provided by the embodiment of the application, as Sb, Ni and Si are added into the steel, the decarburization phenomenon can be reduced by using Sb element, and the Ni and Si avoid the enrichment and precipitation of Sb element, so that a uniform decarburized layer can be obtained.

(3) The preparation method provided by the embodiment of the application can integrate the technological parameters of heating, continuous casting, rolling and coiling before rolling into the cold rolling process of the saw blade steel, and carry out automatic control, thereby further optimizing and shortening the production process and reducing the production cost.

The drawings illustrate:

FIG. 2 is a schematic view of a decarburized layer after the furnace is taken out of the heating furnace in which no Sb element is added, according to the embodiment of the present application, it can be seen from FIG. 2 that the data of random measuring points of the total decarburized layer depth without Sb element are 664.501 μm, 669.772 μm and 731.170 μm.

FIG. 3 is a schematic diagram showing edge cracking caused by excessive addition of Sb element to 65Mn saw blade steel according to an embodiment of the present invention, and it can be seen from FIG. 3 that the data of random measuring points of the total decarburization depth of the saw blade steel added with Sb element are 230.681 μm, 180.343 μm and 172.041 μm, and it can be seen from FIGS. 2 and 3 that the addition of Sb element effectively reduces the depth of the decarburized layer.

Fig. 4 is a schematic diagram of edge cracking caused by excessive Sb added to a 65Mn saw blade steel according to an embodiment of the present disclosure, and it can be seen from fig. 4 that when the Sb element is excessively added, the edge of the saw blade steel cracks.

fig. 6 is a schematic view of the 65Mn saw blade steel provided by the embodiment of the present application, in which the Sb element is added to enrich the surface layer, and as can be seen from fig. 5 and 6, when the Sb element exceeds the dissolution limit, a molten liquid phase is formed, which results in a situation of "hot brittleness" of the surface of the steel plate.

It is noted that, herein, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A65 Mn saw blade steel, characterized in that the saw blade steel comprises, in mass fraction: c: 0.65% -0.75%, Si: 0.3% -0.4%, Mn: 1.1% -1.2%, Sb: 0.01-0.03%, Ni: 0.05 to 0.01 percent, and the balance of Fe and inevitable impurities.

2. The saw blade steel according to claim 1, wherein the metallographic structure of the saw blade steel comprises, in volume fraction: ferrite is less than or equal to 5 percent, and pearlite is more than or equal to 95 percent.

3. Saw blade steel according to claim 1, characterized in that the total decarburized layer depth of the saw blade steel is 5-15 μm.

4. A method of producing a saw blade steel according to any one of claims 1 to 3, characterized in that the method comprises:

obtaining molten steel containing the chemical components;

the finish rolling comprises a second sub-section, and the temperature of the second sub-section is 1000-1050 ℃;

5. The method according to claim 4, wherein the end point temperature of the pre-rolling heating is 1200 ℃ to 1220 ℃ and the time is 140min to 160 min.

6. The method according to claim 4 or 5, wherein the pre-rolling heating comprises a soaking section, the atmosphere of the soaking section is a weakly oxidizing atmosphere, the air excess coefficient of the weakly oxidizing atmosphere is 1.1-1.2, and the oxygen content of the weakly oxidizing atmosphere is 0.01-0.03%;

7. The method of claim 4, wherein the rough rolling further comprises: carrying out rough rolling by adopting a 1+ 5-pass rolling mode, and carrying out side phosphorus removal after rough rolling;

the pressure of the side dephosphorization is 15 MPa-20 MPa.

8. The method of claim 7, wherein the side reduction of the first pass of R2 is ≦ 15mm, the side reduction of the third pass of R2 is ≦ 10mm, and the side reduction of the fifth pass of R2 is ≦ 5 mm.

9. The method of claim 4, wherein the finish rolling is performed at an inlet temperature of 1030 ℃ to 1060 ℃, a finish rolling temperature of 850 ℃ to 880 ℃, and a rolling speed of 9m/s or more.

10. The method of claim 4, wherein the straightening section has a pull rate of 1.4m/min to 1.6 m/min;

the width adjustment amount of the edge part of the fixed width section is less than or equal to 50 mm.