CN112159923B - Mixed casting steel grade and production method for stable mixed casting of special-shaped blank special steel grade - Google Patents

Mixed casting steel grade and production method for stable mixed casting of special-shaped blank special steel grade Download PDF

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CN112159923B
CN112159923B CN202010942369.XA CN202010942369A CN112159923B CN 112159923 B CN112159923 B CN 112159923B CN 202010942369 A CN202010942369 A CN 202010942369A CN 112159923 B CN112159923 B CN 112159923B
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steel
casting
mixed casting
steel grade
mixed
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CN112159923A (en
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韩蕾蕾
邹春锋
杜传治
李四军
李萍
胡滨
石红燕
杜金科
付常伟
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Shandong Iron and Steel Co Ltd
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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
    • 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
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium

Abstract

The invention discloses a mixed casting steel grade and a production method for stable mixed casting of a special-shaped blank special-shaped steel grade, and mainly relates to a method for inserting mixed casting steel grade Q235B-H between a special-shaped blank general carbon Q235B and low alloy steel Q345B when mixed casting; the mixed casting steel type Q235B-H comprises the following components in percentage by mass: 0.09-0.13% of C, 0.25-0.40% of Si, 0.70-0.90% of Mn, less than or equal to 0.030% of P, less than or equal to 0.015% of S, 0.010-0.015% of Nb, 0.020-0.035% of V, and the balance of Fe and inevitable impurities; the invention realizes the smooth mixed casting of Q235B and Q345B, the performance of the mixed casting part is 100 percent qualified, the problem that the steel-making capacity is not matched with the capacity of a section mill is solved, the production continuity is improved, the production cost of each procedure is reduced, and the capacity efficiency is obviously increased.

Description

Mixed casting steel grade and production method for stable mixed casting of special-shaped blank special steel grade
Technical Field
The invention belongs to the field of steel metallurgy and steel making, and particularly relates to a mixed casting steel grade and a production method for stable mixed casting of special-shaped blank and special-shaped steel grade.
Background
The mixed casting of different steel types is a hot problem in the current continuous casting machine research and is also a major technical problem which needs to be solved in lean research and development. The number of Q355B in each specification of the large H-shaped steel is relatively small, and the small bag production mode is very uneconomical. When the Q345B is produced, the continuous casting machine needs to stop casting and replace the tundish for casting replacement, two hours of time is delayed for each casting replacement, and the casting replacement increases the cost of the tundish. Meanwhile, the production characteristics of a steel mill urgently require continuous production of Q235B and Q355B, otherwise, a steel rolling side needs to be subjected to material waiting, a steel making side is opened, a head furnace casting blank needs to fall to the ground, a cold blank needs to be eaten during rolling, a hot blank needs to be stacked on the steel making side, and the processes are repeated, so that energy is wasted, and the production organization difficulty is increased. And the inherent defects caused by the shape of the beam blank continuous casting machine, and the continuous casting of different steel grades can not be realized by carrying out tundish heat exchange. Therefore, the smooth mixed casting of the Q235B and the Q345B is realized, the product performance is stable, and the double indexes of the labor productivity and the economic benefit of the large H-shaped steel wire are related. Meanwhile, due to the great difference between the performances of Q235B and Q345B, the performance index of the product cannot be guaranteed by directly carrying out continuous casting, so that a production method for mixed casting of the special-shaped blank and the different steel is urgently needed.
Disclosure of Invention
The invention aims to provide a mixed casting steel grade and a production method for stable mixed casting of a special-shaped blank special steel grade.
The invention aims to solve the problems that the tensile superposition interval between Q235B and Q345B is too small (the tensile superposition area is 470-500 Mpa), and the control difficulty is higher, designs steel grades which are economical and have lower production difficulty, inserts the steel grades as a mixed casting furnace, and enables the performance of a transition billet to be changed smoothly through process optimization, thereby not only meeting the national standard judgment requirement, but also reducing the influence on the steel rolling side due to component mutation and meeting the characteristic requirements of the capacity of a rolling line of a special-shaped billet and the diversity of product orders.
The technical scheme of the invention is as follows:
a mixed casting steel seed Q235B-H, the composition of the mixed casting steel seed comprises the following components by mass fraction: 0.09-0.13% of C, 0.25-0.40% of Si, 0.70-0.90% of Mn, less than or equal to 0.030% of P, less than or equal to 0.015% of S, 0.010-0.015% of Nb, 0.020-0.035% of V, and the balance of Fe and inevitable impurities;
the performance indexes of the mixed casting steel type Q235B-H comprise the following steps:
the rolling specification is 14-30 mm, the yield strength is not less than 370MPa, the tensile strength is 480-495 MPa, the elongation after fracture is not less than 32%, and the impact energy at 20 ℃ is not less than 50J.
The rolling specification is flange thickness t 2.
The production method for stably pouring the mixed casting steel grade Q235B-H into the special-shaped blank special steel grade comprises the following steps:
1) when the steel grade Q235B and the steel grade Q345B are poured in a mixed manner by a steel-making side beam blank continuous casting machine, the mixed pouring steel grade Q235B-H is inserted in the middle of the mixed pouring;
2) when the steel making side steel type is judged, the steel type Q345B is normally judged according to the original steel type, the mixed casting steel type Q235B-H is judged as the steel type Q235B, and the steel type Q235B is normally judged according to the original steel type;
3) controlling the rolling temperature of the profile steel side: the temperature of the heating furnace is 1250-1300 ℃, the finish rolling temperature is the flange temperature, the initial rolling temperature is 980-1050 ℃, and the final rolling temperature is 850-900 ℃.
Preferably, according to the invention, the production profile in step 1) is BB1 or BB 2; the dimensions of the production section BB1 were 555X 440X 90mm, and the dimensions of the production section BB2 were 750X 370X 90 mm.
Preferably, according to the invention, the casting sequence of the continuous casting machine in step 1) is as follows:
firstly, pouring steel grades from front to back: Q235B, Q235B-H, Q345B;
secondly, pouring steel grades from front to back: Q345B, Q235B-H, Q235B.
According to the invention, the performance indexes of the judgment of the steel grade Q235B and the steel grade Q345B in the step 2) are as follows:
designation Q235B: according to the standard GB/T700, the yield strength is not less than 235MPa when the thickness is not more than 16mm, the yield strength is not less than 225MPa when the thickness is more than 16-40 mm, the tensile strength is 370-500 MPa, the elongation after fracture is not less than 26%, and the impact energy at 20 ℃ is not less than 27J;
Designation Q345B: according to the standard GB/T1591, the yield strength is not less than 345MPa when the thickness is not more than 16mm, the yield strength is not less than 335MPa when the thickness is more than 16-40 mm, the tensile strength is 470-630 MPa, the elongation after fracture is not less than 20%, and the impact energy at 20 ℃ is not less than 34J.
Because different specifications of the steel rabbet have certain difference, the method related by the invention is suitable for sections with other similar specifications, and the rolled material specification of the section steel is as follows: height H width B web thickness t1 flange thickness t 2.
The technical scheme of the invention has the beneficial effects
1. The invention relates to a mixed casting steel type Q235B-H, the performance of the mixed casting steel type is in accordance with the tiny overlapping area of the performance of the steel type Q235B and the steel type Q345B, the performance fluctuation is small, and the stability is high.
2. The invention relates to a production method for stably pouring mixed casting steel variety for special-shaped blank special-shaped steel variety, which is characterized in that when a steel variety Q235B and a steel variety Q345B are poured by a steel-making side special-shaped blank continuous casting machine for mixed casting, the mixed casting steel variety Q235B-H is inserted between the steel variety Q235B and the steel variety Q345B, so that the mixed casting continuous production of the steel variety Q235B and the steel variety Q345B is realized, the accurate control level of mixed casting performance is improved, the qualified performance of steel products of a mixed casting part is realized, and great contribution is made to the capacity improvement of a steel production line and the overall cost reduction of products.
Detailed Description
The invention is further illustrated with reference to specific examples of embodiment but the scope of protection is not limited thereto.
Covering slag: MOP-SXS-60X, available from Chuan and Feng metallurgy of Liaoning, Inc.
Example 1
A production method for stable mixed casting of a special-shaped blank and a special steel grade comprises the following steps:
1) when the casting steel grade Q345B of the steel-making side beam blank continuous casting machine is converted into the casting steel grade Q235B, the mixed casting steel grade Q235B-H is inserted after the casting steel grade Q345B, and the casting sequence of the continuous casting machine is shown in a table 1; the mixed casting steel seed Q235B-H comprises the components shown in the table 2 according to the mass fraction, and the balance of Fe and inevitable impurities; the parameters for producing the mixed casting steel Q235B-H on the continuous casting machine are shown in Table 3.
2) When the steel-making side steel grade is judged, the steel grade Q345B is judged according to GB/T1591, the steel grade Q235B is judged according to GB/T700, and the performance indexes of the steel grade Q345B and the steel grade Q235B are shown in Table 4; the mixed casting steel type Q235B-H is judged to be Q235B, and the actual performance indexes are shown in Table 5; the actual performance indexes of the steel grades Q235B and Q345B are shown in Table 6.
3) Controlling the rolling temperature of the Q235B-H-shaped steel side, controlling the temperature of a heating furnace at 1275 ℃, and finish rolling: flange temperature, initial rolling: 1020 ℃, finish rolling: 890 ℃.
TABLE 1
Figure BDA0002674064670000031
TABLE 2
Furnace number C％ Si％ Mn％ P％ S％ Nb％ V％
H191-08469 0.12 0.32 0.76 0.015 0.005 0.013 0.025
TABLE 3
Figure BDA0002674064670000041
TABLE 4
Figure BDA0002674064670000042
TABLE 5
Figure BDA0002674064670000043
TABLE 6
Figure BDA0002674064670000044
Table 6 illustrates: the pouring sequence is Q345B and Q235B-H, Q235B, so that Q345B is described, and the nth branch is the last branch of Q345B; describing Q235B, the 1 st casting blank of the Q235B heat is the first casting blank, and the rest can be analogized in turn.
Example 2
The difference from example 1 is that: the casting sequence of the continuous casting machine is shown in Table 7, the composition of the mixed casting steel Q235B-H comprises the following components in percentage by mass shown in Table 8, and the balance is Fe and inevitable impurities; the conditions for producing the mixed casting steel variety Q235B-H on the continuous casting machine are shown in Table 9; the performance indexes of the steel grades Q345B and Q235B are shown in Table 10; the actual performance index of the mixed casting steel Q235B-H is shown in Table 11; the actual performance indexes of the steel grades Q235B and Q345B are shown in Table 12.
Q235B-rolling temperature control of H-shaped steel side: the temperature of the heating furnace is 1270 ℃, and finish rolling is carried out: flange temperature, initial rolling: finishing rolling at 1000 ℃: 892 deg.C.
TABLE 7
Figure BDA0002674064670000051
TABLE 8
Furnace number C％ Si％ Mn％ P％ S％ Nb％ V％
H193-03531 0.10 0.30 0.76 0.015 0.008 0.012 0.025
TABLE 9
Figure BDA0002674064670000052
Watch 10
Figure BDA0002674064670000061
TABLE 11
Figure BDA0002674064670000062
TABLE 12
Figure BDA0002674064670000063
Table 12 illustrates: the pouring sequence is Q235B, Q235B-H, Q345B, so Q235B is described, and the nth branch is the last branch of the heat; describing Q345B, the 1 st casting blank is the first casting blank of the Q345B heat, and the rest can be analogized in turn.
Example 3
The difference from example 1 is that: the casting sequence of the continuous casting machine is shown in Table 13, the composition of the mixed casting steel Q235B-H comprises the following components in percentage by mass shown in Table 14, and the balance is Fe and inevitable impurities; the balance is that the conditions for producing the mixed casting steel Q235B-H on the continuous casting machine are shown in the table 15; the performance indexes of the steel grade Q345B and the steel grade Q235B are shown in Table 16; the actual performance indexes of the mixed casting steel Q235B-H are shown in Table 17; the actual performance indexes of the steel grades Q235B and Q345B are shown in Table 18.
Q235B-rolling temperature control of H-shaped steel side: the temperature of a heating furnace is 1280 ℃, and finish rolling is carried out: flange temperature, initial rolling: 1010 ℃, finish rolling: at 900 ℃.
Watch 13
Figure BDA0002674064670000071
TABLE 14
Furnace number C％ Si％ Mn％ P％ S％ Nb％ V％
H192-06136 0.11 0.32 0.78 0.014 0.006 0.013 0.028
Watch 15
Figure BDA0002674064670000072
TABLE 16
Figure BDA0002674064670000073
TABLE 17
Figure BDA0002674064670000081
Watch 18
Figure BDA0002674064670000082
Table 18 illustrates: the pouring sequence is Q345B, Q235B-H, Q235B, so Q345B is described, and the nth branch is the last branch of the heat; describing Q235B, the 1 st casting blank of the Q345B heat is the first casting blank of the Q345, and the rest can be analogized in turn.
The results of the analysis show that the performance of the mixed casting steel type Q235B-H produced by the examples 1-3 completely meets the mixed casting performance requirements of Q235B and Q345B, when the dissimilar billet Q235B and Q345B are mixed cast, the Q235B-H steel type is inserted between the dissimilar billet Q235B and the Q345B, the performance of the mixed casting steel completely meets the requirement of the superposition part of the Q235B and the Q345B, the national technical standard requirement is completely met, and the performance qualification rate of the mixed casting steel reaches 100%.
By adopting the technical scheme of the invention to carry out mixed casting smelting on the H-shaped steel carbon structural steel and the low alloy steel, the practical application effect is obvious, the prominent difficult problem that the performance overlapping area is small when the special-shaped blank smelting Q235B and Q345B are mixed cast is solved, and the technical bottleneck problems of system study in the component design of mixed cast steel types, analysis of the mixed cast performance, accurate control and the like are difficult; the invention not only improves the labor productivity of the H-shaped steel wire, but also brings great economic benefit.
The method can be realized by upper and lower limit values of intervals of process parameters (such as temperature, components and the like) and interval values, and embodiments are not listed.
Those skilled in the art will recognize that the invention may be practiced without these specific details.
Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or substituted with equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims (2)

1. The application of a mixed casting steel grade Q235B-H in mixed casting of a steel grade Q235B and a steel grade Q345B is characterized in that the components of the mixed casting steel grade comprise the following components in percentage by mass: 0.09-0.13% of C, 0.3-0.40% of Si, 0.70-0.90% of Mn, less than or equal to 0.030% of P, less than or equal to 0.015% of S, 0.010-0.015% of Nb, 0.025-0.035% of V, and the balance of Fe and inevitable impurities;
the production method for mixed casting of the steel grade Q235B-H and the steel grade Q235B and Q345B comprises the following steps:
1) when steel grade Q235B and steel grade Q345B are poured in a steel-making side beam blank continuous casting machine for mixed casting, mixed casting is inserted in the middle of mixed casting
Steel grade Q235B-H;
2) when the steel making side steel type is judged, the steel type Q345B is normally judged according to the original steel type, the mixed casting steel type Q235B-H is judged as the steel type Q235B, and the steel type Q235B is normally judged according to the original steel type;
3) controlling the rolling temperature of the profile steel side: the temperature of the heating furnace is 1250-1300 ℃, the finish rolling temperature is the flange temperature, the initial rolling temperature is 1000-1050 ℃, and the final rolling temperature is 890-900 ℃;
the performance indexes of the mixed casting steel type Q235B-H comprise the following steps:
the rolling specification is 14-30 mm, the yield strength is not less than 370MPa, the tensile strength is 480-495 MPa, the elongation after fracture is not less than 32%, and the impact energy at 20 ℃ is not less than 50J;
the casting sequence of the continuous casting machine in the step 1) is as follows:
firstly, pouring steel grades from front to back: Q235B, Q235B-H, Q345B;
and secondly, pouring steel grades from front to back: Q345B, Q235B-H, Q235 38235 235B.
2. The use according to claim 1, wherein the profile of the preform in step 1) is BB1 or BB 2; the dimensions of production section BB1 were 555 × 440 × 90mm, and the dimensions of production section BB2 were 750 × 370 × 90 mm.
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JPS59225857A (en) * 1983-06-06 1984-12-18 Nippon Steel Corp Continuous casting method of different kinds of steel
CN103706775B (en) * 2013-12-13 2016-04-20 内蒙古包钢钢联股份有限公司 Wide thickness plate continuous casting machine waters method of operating with watering time different steel grade long company
CN105798250B (en) * 2016-03-22 2018-01-23 首钢总公司 A kind of determination method of middle base
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