CN110656223B - Transversely-variable-thickness wide quenched and tempered steel plate and preparation method thereof - Google Patents
Transversely-variable-thickness wide quenched and tempered steel plate and preparation method thereof Download PDFInfo
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- CN110656223B CN110656223B CN201810690955.2A CN201810690955A CN110656223B CN 110656223 B CN110656223 B CN 110656223B CN 201810690955 A CN201810690955 A CN 201810690955A CN 110656223 B CN110656223 B CN 110656223B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
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- B21C37/00—Manufacture of metal sheets, bars, wire, tubes or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
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- C—CHEMISTRY; METALLURGY
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- C21D6/00—Heat treatment of ferrous alloys
- C21D6/001—Heat treatment of ferrous alloys containing Ni
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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- C—CHEMISTRY; METALLURGY
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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
- B21B1/38—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling sheets of limited length, e.g. folded sheets, superimposed sheets, pack rolling
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Abstract
A width quenching and tempering steel plate with transversely variable thickness and a preparation method thereof are provided, the thickness of the steel plate is monotonously and linearly increased or decreased in sections in the width direction; the longitudinal section of the steel plate is rectangular, the cross section of the steel plate is a right trapezoid or consists of a plurality of right trapezoids and a rectangle, and one steel plate with the section can be overlapped with another steel plate with the same section to form a cuboid after being respectively rotated by 180 degrees in the horizontal direction and the vertical direction; the difference between the maximum plate thickness and the minimum plate thickness of the steel plate is not more than 15mm, the ratio of the maximum plate thickness to the minimum plate thickness is not more than 2:1, and the ratio of the difference between the maximum plate thickness and the minimum plate thickness to the width is not more than 1: 200; the steel plate is subjected to quenching heat treatment and tempering heat treatment. The steel plate can be economically produced in batch by adopting mature heating, steel rolling, quenching and tempering heat treatment processes through the existing heating, steel rolling and heat treatment equipment.
Description
Technical Field
The invention relates to a wide and thick steel plate production technology, in particular to a wide quenched and tempered steel plate with transversely variable thickness and a preparation method thereof, which are suitable for manufacturing various differential thick steel plates in the industries of shipbuilding, bridges, buildings, energy sources and chemical industry.
Background
In industrial production and daily life, steel sheets delivered in a quenched and tempered state (i.e., a quenched and tempered state) are very common. The quenched and tempered steel plate is widely applied to the industries of shipbuilding, bridges, buildings, energy, chemical engineering and the like.
However, quenched and tempered steel sheets are generally flat, that is, the sheet thickness is always constant in the longitudinal direction or the width direction of the steel sheet, and a cross section of any one of the steel sheets perpendicular to the longitudinal direction or the width direction is constant as a rectangle. However, in many cases, the distribution of the load borne by the steel plate along the length direction or the width direction of the steel plate is not constant, but gradually increases or gradually decreases, and therefore, designers often expect that the thickness of the steel plate is not constant, but can be gradually increased or gradually decreased along the length direction or the width direction according to the distribution rule of the load. In other words, the cross section perpendicular to the width or length direction of the steel sheet is not a rectangle, but a right-angled trapezoid or other irregular cross section.
Such a quenched and tempered steel sheet with a variable thickness in the longitudinal direction or the width direction is called a differential thickness quenched and tempered steel sheet.
The quenched and tempered steel plate with a variable thickness along the rolling direction (i.e., the length direction) is referred to as a longitudinal differential thickness quenched and tempered steel plate, and the quenched and tempered steel plate with a variable thickness along the direction perpendicular to the rolling direction (i.e., along the width direction) is referred to as a transverse differential thickness quenched and tempered steel plate.
The quenched and tempered steel is a steel plate produced by a 'quenching and tempering' heat treatment process, wherein the quenching process is that a rolled steel plate is heated to a quenching temperature through a quenching furnace and then is rapidly cooled to below a specific temperature through a quenching machine by water at a specific cooling rate. The tempering process is to heat the quenched steel plate to a tempering temperature through a tempering furnace, keep the temperature for a specific time, and cool the steel plate to room temperature after the steel plate is taken out of the furnace.
The quenched and tempered steel has the characteristics of high strength and good toughness. However, the manufacturing cost and the added value of tempering are higher, and the most direct advantage of adopting the poor-thickness tempered steel plate is that the using amount of steel can be saved. However, the saving of the steel consumption is not the main motivation of designers to choose the poor-thickness and quality-adjusted steel plate, and the main motivation is to reduce the self weight of the steel plate. For example, the steel plates with different thickness are used on large ships and large bridges. In both cases, designers and users desire to design the steel plates so that the thickness of the steel plates can be increased or decreased gradually along the length direction or the width direction (provided that the bearing capacity is ensured to be increased or decreased), namely, the steel plates are designed into transverse or longitudinal differential thickness steel plates according to the distribution rule of the load, so as to reduce the self weight of the steel plates to the minimum.
Under the existing wide and thick plate rolling mill equipment conditions, the rolling production process of a longitudinal differential thick steel plate (also called as a wedge-shaped steel plate in the wide and thick plate industry) is relatively mature, meanwhile, quenching equipment of wide and thick plate manufacturers at home and abroad is mostly a roller hearth type heating furnace and a roller press type quenching machine, a tempering furnace is mostly a roller hearth type heating furnace, and the equipment can be used for quenching and tempering the longitudinal differential thick steel plate under the limitation of certain process conditions (called as process windows) after necessary transformation. Because of this, longitudinally differential thickness-conditioned steel sheets have found individual applications in practical engineering. In contrast, limited by the existing wide and thick plate rolling technology, so far, the transverse thickness difference tempered steel plate, especially the transverse thickness difference tempered steel plate with the length of more than 5 meters and the width of more than 2.0 meters, is rarely applied in practical engineering, and no papers and patents on the manufacturing process and application aspect of the transverse thickness difference tempered steel plate are published. In fact, in practical engineering, the requirement for the transverse thickness difference modulated steel plate, especially for the transverse thickness difference modulated steel plate with the length greater than 5m and the width greater than 2.0 m, is still relatively large, even more general than the requirement for the longitudinal thickness difference modulated steel plate, and typical application occasions thereof are as follows: the steel plate with different thickness on a large ship, a large sluice gate, a large bridge and the like. In addition, for some high-strength steel plates for large storage tanks and large wind power generation tower bases, the industrial design requirement of adopting transverse thickness difference and width quenched and tempered steel plates is also existed.
It is known to produce transversely differentiated thickness-conditioned steel sheets, in the first place to obtain rolled steel sheets of transversely variable thickness. In the prior art, some special transverse differential thick steel plates can be rolled by a section mill, a hot continuous rolling mill or a reversible rolling mill with matched hole patterns and roll diameters. However, these transverse differential thickness steel sheets rolled by the section rolling mill, the hot continuous rolling mill or the reverse rolling mill have the following problems:
1) in order to avoid the occurrence of the camber, when designing the pass/roll diameter of the shape rolling mill, hot continuous rolling mill or reversible rolling mill, the cross section in the width direction is usually left-right symmetrical (i.e., horizontally symmetrical), and therefore, the shape rolling mill, hot continuous rolling mill or reversible rolling mill can usually produce only the laterally symmetrical differential thickness steel plate.
2) The steel plate width is generally narrow.
3) When a profile rolling mill, a hot continuous rolling mill or a reversible rolling mill is used for producing a differential thickness steel plate, different specifications (namely different cross sections) need different hole patterns or roll diameter designs. Therefore, for small batches of multi-gauge differential thickness steel sheet products, if the steel sheet products are produced by a section mill, a hot continuous mill or a reversible mill, the pass and the roll need to be frequently replaced, which is obviously uneconomical and unrealistic.
In addition, there is an attempt to produce a transverse differential thickness steel plate by directly using a transverse wedge rolling process through a design of a constant pass or roll diameter. Chinese patent application No. CN201310227028.4 discloses a method for producing a transverse wedge-shaped rolled variable-thickness steel plate, in the technical scheme, the rolling of the transverse variable-thickness steel plate is completed in two steps. The method comprises the following steps: transverse rolling, namely performing longitudinal variable cross-section rolling on the steel plate according to the average thickness set value of the head and the tail of the steel plate when the steel plate is rolled in the last pass of the transverse rolling stage; step two: longitudinal rolling, namely firstly, performing transverse equal-proportion wedge rolling in a longitudinal rolling stage according to the longitudinal thickness change values of the head and the tail generated in a transverse rolling stage; and then, determining the roll gap adjustment amount and the roll bending force set value by adopting an influence function method according to the rolling schedule distribution, and ensuring that the transverse thickness distribution of the longitudinal rolling pass meets the equal proportion wedge requirement. The technical scheme also has the following defects:
1) the wedge degree is constant, namely the plate thickness in the width direction can only change according to a certain slope;
2) the existing production line of wide and thick plates with the thickness of more than 2.8 meters comprises equipment such as wide and thick plate rolling mills, hot straightening machines, cold straightening machines, shearing machines and the like, and is not suitable for producing the differential thick steel plate with the transverse wedge degree (namely the thickness difference of two sides of the steel plate) of more than 5mm, which is claimed by the embodiment of the production line, unless the production line is subjected to great modification; the existing wide and thick plate rolling mill with the width of more than 2.8 meters can not normally produce under the condition that the roll gap difference (the roll gap difference between the transmission side and the fixed side) on two sides set by the embodiment of the rolling mill is as high as 8.54mm (95.47mm-86.93 mm);
3) when the transverse wedge degree is larger, the temperature drop speeds of the two sides of the steel plate are definitely different, and the shape and the performance uniformity of the steel plate are difficult to ensure.
The second step of the production of the poor-thickness and quality-adjustable steel plate is to carry out the quality-adjustable heat treatment on the rolled steel plate, namely the 'quenching and tempering' heat treatment.
However, unless a quenching furnace, a quenching machine and a tempering furnace including a roller way, a burner control system and a water nozzle control system are modified in a large quantity, it is difficult to perform quenching and tempering heat treatment on the transverse differential thickness steel plate by using the conventional quenching furnace, quenching machine and tempering furnace equipment, so as to ensure normal traveling of the steel plate in the furnace and uniform and stable performance of the steel plate. Moreover, if the thickness difference of the steel plates is too large, no matter how the equipment is modified, it is difficult to set a proper quenching heat preservation time, tempering heat preservation time and quenching cooling rate, so that the heat preservation time is not too long and the steel plate walking speed is not too slow for the thinnest side steel plate, and the heat preservation time is not too short and the steel plate walking speed is too fast for the thickest side steel plate. In short, if the difference in the thickness of the steel sheets is too large, it will inevitably happen that the "process window" is too narrow or even not at all.
Disclosure of Invention
The invention aims to provide a wide quenched and tempered steel plate with transversely variable thickness and a preparation method thereof, wherein the thickness of the steel plate is monotonically and linearly increased or decreased in a sectional manner in the width direction; the steel plate can be economically produced in batch by adopting mature heating, steel rolling, quenching and tempering heat treatment processes through the existing heating, steel rolling, quenching and tempering heat treatment equipment.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a widthwise variable thickness wide quenched and tempered steel sheet, the thickness of which increases or decreases monotonously and linearly in sections in the width direction; the longitudinal section of each steel plate is rectangular, the cross section of each steel plate is a right-angled trapezoid or consists of a plurality of right-angled trapezoids and a rectangle, after one steel plate with the section is rotated by 180 degrees in the horizontal direction and the vertical direction, the slope surface of the steel plate can be attached to the slope surface of the other steel plate with the same section, and the two steel plates are overlapped to form a cuboid, namely a overlapped differential thickness steel plate; the steel plate is subjected to quenching heat treatment and tempering heat treatment; the difference between the maximum plate thickness and the minimum plate thickness of the steel plate is not more than 15mm, the ratio of the maximum plate thickness to the minimum plate thickness is not more than 2:1, and the ratio of the difference between the maximum plate thickness and the minimum plate thickness to the width is not more than 1: 200.
The invention relates to a preparation method of a wide quenched and tempered steel plate with transversely variable thickness, which comprises the following steps:
1) preparation of superimposed blanks
The device is formed by overlapping two intermediate blanks with the same shape and size, wherein one of the upper surface and the lower surface of the intermediate blank is a non-horizontal plane with a slope surface, namely a slope surface, while the other surface is a horizontal plane; among the cross section and the longitudinal section, the geometric shape of one section is a right trapezoid or a polygon formed by a plurality of right trapezoids and rectangles, namely a differential thickness surface, and the geometric shape of the other section is a rectangle; the ratio of the thickness Hx of the middle blank at a certain point in the width direction to the thickness Tx of the finished differential thickness steel plate at the corresponding position, namely the compression ratio, is controlled to be 2-6 times, wherein the compression ratio of the thicker side is larger than that of the thinner side; for hot continuous rolling and steckel rolling mills, the width Wp of the intermediate blank is greater than the width W of the finished product differential thick steel plate, and the reversible wide and thick plate rolling mill has no limitation;
2) the slope surfaces of the two intermediate blanks are subjected to leveling and surface cleaning treatment to remove surface defects such as cracks, slag inclusions, pits and the like visible to the naked eye and high-temperature iron scales, so that the finished poor-thickness steel plate is ensured to obtain good surface quality;
3) the peripheries of the two middle blanks are subjected to groove processing, and a slope surface of one of the two blanks is coated or covered with a separant; after the other blank is rotated by 180 degrees in the horizontal direction and the vertical direction respectively, the slope surface of the other blank is jointed with the slope surface of the blank coated or covered with the separant to form a superposed blank;
4) carrying out discontinuous welding on the superposed blank along the middle groove gap;
5) manufacture of differential thickness steel plate
Heating, rolling and straightening the superposed blank by the same heating, rolling and straightening processes as those of a flat quenched and tempered steel plate of the same steel type to obtain a superposed differential thick steel plate, wherein the thickness Tz of the superposed differential thick steel plate is larger than the sum of the maximum thickness and the minimum thickness of the differential thick steel plate, the width Wz of the superposed differential thick steel plate is larger than the width W of the differential thick steel plate, and the length Lz of the superposed differential thick steel plate is larger than the length L of the differential thick steel plate;
carrying out necessary hot straightening and cold straightening on the overlapped differential thick steel plate by adopting the existing mature technology, and before trimming and sizing, conveying the steel plate into a quenching heat treatment furnace and a quenching machine through lifting equipment for quenching treatment; the quenching process of the differential thickness steel plate is the same as that of a flat steel plate of the same steel type except for the in-furnace time and the heat preservation time; during quenching treatment:
the furnace time is A Tz, the heat preservation time is B Tz, and the unit of min is obtained;
wherein A is a furnace time thickness coefficient, and is 1.8-4.0 in unit of min/mm;
b is a heat preservation time thickness coefficient, and the unit min/mm is 1.2-3.0;
tz is the thickness of the laminated steel plate and the unit mm;
6) conveying the overlapped existing differential thickness steel plate into a tempering heat treatment furnace for tempering treatment through lifting equipment; except for the furnace time and the heat preservation time, the tempering process of the differential thickness steel plate is the same as that of the flat steel plate of the same steel type; and (3) tempering:
the furnace time is A Tz, the heat preservation time is B Tz, and the unit of min is obtained;
wherein A is a furnace time thickness coefficient, and A is 2.5-8.0, unit min/mm;
b is a heat preservation time thickness coefficient, and the unit min/mm is 1.5-7.0;
tz is the thickness of the laminated steel plate and the unit mm;
7) and (3) trimming and sizing the quenched and tempered superposed steel plate, namely cutting off the width allowance and the length allowance, and separating the upper layer steel plate and the lower layer steel plate to finally obtain two transverse thickness-difference quality-adjusting steel plates with required dimension specifications.
Preferably, the intermediate blank is directly cast into a steel ingot with the differential thickness surface by adopting a die casting process; or a rectangular blank is obtained by a continuous casting process, and is rolled into an cogging material with the differential thickness surface by longitudinally changing the thickness of the rectangular blank through a wide and thick plate rolling mill.
In step 3), the laminated material is combined in multiple scales in the longitudinal direction or in multiple widths in the width direction to form a laminated material having a larger unit weight of multiple scales or multiple widths.
The invention has the beneficial effects that:
the manufacturing method of the wide quenched and tempered steel plate with the transversely variable thickness provided by the invention can achieve the following effects:
1) the existing heating, steel rolling, straightening, heat treatment, hoisting and other equipment, such as the existing continuous heating furnace, a wide and thick plate rolling mill, a hot straightening machine, a quenching heat treatment furnace, a quenching machine, a tempering heat treatment furnace, a magnetic disc crane and other equipment, are utilized, and mature heating, rolling, straightening and quenching heat treatment processes are adopted, so that the transversely variable-thickness wide quenched and tempered steel plates, namely the transversely poor-thickness wide quenched and tempered steel plates or the poor-thickness steel plates for short can be economically produced in batches.
2) The manufacturing method provided by the invention can not generate the limit of 'process window' of quenching and tempering heat treatment due to the thickness difference of the steel plate.
3) The width and length of the differential thickness steel plate can reach the normal range of a flat wide width quenched and tempered steel plate, for example: the maximum width can reach 4800mm, and the maximum length can reach 25000 mm.
4) The sum Tz of the maximum thickness Tb and the minimum thickness Ta of the differential thickness steel plate can reach the normal thickness range of the flat wide quenched and tempered steel plate.
5) The cross section of the differential thickness steel plate can be a single trapezoid, and can also be a polygon formed by a plurality of right-angle trapezoids and rectangles, so that the thickness change of the steel plate in the width direction can be one slope, and can also be a plurality of slopes.
6) Within the range of the whole plate, the thickness difference is not more than 15mm, the thickness difference ratio is not more than 2:1, and the thickness difference ratio is not more than 1: 200.
7) The used blank can be a traditional continuous casting blank or a traditional die casting blank, so that the manufacturing cost is greatly reduced.
Drawings
FIG. 1 is a schematic structural view of a transverse differential thickness wide width quenched and tempered steel plate of the present invention; in the figure, 1 is a transverse differential thickness wide width quenched and tempered steel plate, 11 is a differential thickness surface, 12 is a slope surface, W is a width of the differential thickness steel plate, W1, W2 and W3 … … are widths of respective width sections, L is a length of the differential thickness steel plate, Ta is a minimum thickness of the steel plate, Tb is a maximum thickness of the steel plate, T1 and T2 … … are maximum plate thickness or minimum plate thickness of the respective width sections of the steel plate, and Tx is a thickness at a certain position of the steel plate. After the steel plate with the differential surface 11 is rotated by 180 ° in each of the horizontal and vertical directions, the steel plate may be stacked with another steel plate with the same differential surface to form a rectangular parallelepiped, and the rectangular parallelepiped may be formed to have a height of Ta + Tb and a width of W.
Fig. 2 is a schematic view of a single overlapped differential thickness steel plate obtained by stacking two differential thickness steel plates according to the present invention, wherein 1 and 2 are the two differential thickness steel plates, respectively, and 11 and 21 are the differential thickness surfaces of the two differential thickness steel plates, respectively. After one of the two steel plates rotates 180 degrees in the horizontal direction and the vertical direction, the slope surface of the two steel plates can be attached to the slope surface of the other steel plate with the same section, and the two steel plates are overlapped to form a cuboid, namely a overlapped differential thickness steel plate; wz and Lz are respectively the width and length of the superposition difference thick steel plate, Tz is the thickness of the superposition difference thick steel plate, Ta is the minimum thickness of two tension difference thick steel plates, and Tb is the maximum thickness of the two tension difference thick steel plates.
Fig. 3 is a schematic diagram of the intermediate blank of the present invention, in which 3 is the intermediate blank, 32 is a slope surface, 31 is a differential thickness surface, Lp and Wp are respectively the length and width of the intermediate blank, W is the width of the differential thickness steel plate, W0 is the trimming margins on the left and right sides, Wp1, Wp2, Wp3 … … are respectively the width of each width section, Ha is the minimum thickness of the blank, Hb is the maximum thickness of the blank, Hx is the thickness of the blank at a certain width position, and H1, H2, … … are respectively the maximum thickness or the minimum thickness of the blank in each width section. The difference surface 31 may be formed into a rectangular parallelepiped by being rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately shifted, and then the height Ha + Hb and the width Wp of the rectangular parallelepiped may be stacked on the original difference surface 31.
Fig. 4 is a schematic diagram of two intermediate blanks overlapped and welded into an overlapped blank in the embodiment of the invention, wherein 3 and 4 are the two intermediate blanks after surface treatment and beveling respectively, 5 is a discontinuous welding seam between the two intermediate blanks, 31 and 41 are the difference thickness surfaces of the two intermediate blanks respectively, Ha is the minimum thickness of the intermediate blank, Hb is the maximum thickness of the intermediate blank, and Hp is the thickness of the overlapped blank. Considering the factors of a separating agent and the like, Hp is slightly larger than Ha + Hb, H3x and H4x are the thicknesses of the two middle blanks at a certain width position respectively, Lp, Wp and Hp are the length, the width and the thickness of the two middle blanks which are overlapped and welded into an overlapped blank respectively, W is the width of a steel plate, and W0 is the margin of trimming.
Fig. 5 is a schematic view of a transverse differential thickness steel plate in example 2 of the present invention, in which 1 is the transverse differential thickness steel plate, 11 is a differential thickness surface, 12 denotes a slope surface, W is the width of the differential thickness steel plate, L is the length of the differential thickness steel plate, Ta is the minimum thickness of the steel plate, Tb is the maximum thickness of the steel plate, and Tx is the thickness of the steel plate at a certain width position.
Fig. 6 is a schematic view of an intermediate material in example 2 of the present invention, in which 3 is the intermediate material, 32 is a slope surface, 31 is a difference thickness surface, Lp and Wp are the length and width of the intermediate material, W is the width of the difference thickness steel plate, and W0 is the trimming margins on the left and right sides. Ha is the minimum thickness of the blank, Hb is the maximum thickness of the blank, and Hx is the thickness of the blank at a certain width position. The difference surface 31 may be formed into a rectangular parallelepiped by being rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately shifted, and then the height Ha + Hb and the width Wp of the rectangular parallelepiped may be stacked on the original difference surface 31.
Fig. 7 is a schematic diagram of a superimposed blank in embodiment 2 of the present invention, in which 3, 4 are two intermediate blanks after surface treatment and beveling, 5 is a welding seam welded discontinuously along peripheral bevels of the two intermediate blanks, 31, 41 are differential thickness surfaces of the two intermediate blanks, Ha is the minimum thickness of the intermediate blank, Hb is the maximum thickness of the intermediate blank, Hx is the thickness of the intermediate blank at a certain width position, and Lp, Wp, and Hp are the length, width, and thickness of the superimposed blank obtained by superimposing and welding the two intermediate blanks.
Fig. 8 is a schematic view of a single overlapped differential thick steel plate formed by overlapping two transverse differential thick steel plates in example 2 of the present invention, in which 1 and 2 are the two transverse differential thick steel plates, respectively, and 11 and 21 are the differential thick surfaces of the right trapezoid of the two steel plates, respectively. After one of the two steel plates rotates 180 degrees in the horizontal direction and the vertical direction, the slope surface of the two steel plates can be attached to the slope surface of the other steel plate with the same section, and the two steel plates are overlapped to form a cuboid, namely a overlapped differential thickness steel plate; and overlapping the differential thickness steel plates, wherein Wz, Lz and Tz are respectively the width, length and thickness of the overlapping differential thickness steel plates, Ta is respectively the minimum thickness of the two differential thickness steel plates, Tb is respectively the maximum thickness of the two differential thickness steel plates, and T1x and T2x are respectively the thicknesses of the two steel plates at certain width positions.
Detailed Description
The invention is further illustrated by the following examples and figures.
The invention provides a set of technical scheme for economically and massively producing wide quenched and tempered steel plates with transversely variable thickness by using the existing heating, rolling, roller bed, traveling, straightening and quenching and tempering heat treatment equipment and adopting a mature process.
1) The invention designs a novel laminated blank which can be rolled into a wide quenched and tempered steel plate (hereinafter referred to as a differential thickness quenched and tempered steel plate or a differential thick steel plate) with transversely variable thickness by the prior heating, steel rolling, straightening, quenching and tempering heat treatment and hoisting equipment and adopting the prior art, and the differential thick steel plate has the following characteristics:
firstly, the cross section (hereinafter referred to as a differential thickness surface) of the steel plate, which is vertical to the rolling direction, is a right trapezoid or a polygon formed by a plurality of right trapezoids and rectangles; one of the upper and lower surfaces of the steel plate is necessarily a non-horizontal surface (hereinafter referred to as a slope surface) that is inclined in stages, and the other surface is a horizontal surface. The longitudinal section of the steel sheet parallel to the rolling direction is rectangular.
② in the above differential thickness surface, the plate thickness may be linearly increased or decreased stepwise monotonously in the width direction. The difference between the maximum plate thickness and the minimum plate thickness (hereinafter referred to as thickness difference) is not more than 15mm in the whole plate range; the ratio of the maximum thickness to the minimum thickness (hereinafter referred to as the difference thickness ratio) is not more than 2:1, and the ratio of the difference between the maximum thickness and the minimum thickness to the width (hereinafter referred to as the difference thickness ratio) is not more than 1:200, as shown in fig. 1.
Referring to fig. 1, 1 is a differential thickness steel plate, 11 is a differential thickness surface, 12 is a slope surface, W is a width of the differential thickness steel plate, W1, W2 and W3 … … are widths of respective width sections, L is a length of the differential thickness steel plate, Ta is a minimum thickness of the steel plate, Tb is a maximum thickness of the steel plate, T1 and T2 … … are maximum plate thicknesses or minimum plate thicknesses of respective width sections of the steel plate, and Tx is a thickness at a certain position of the steel plate.
The differential thickness surface has the following characteristics: after rotating 180 degrees in the horizontal direction and the vertical direction respectively and shifting properly, the two parts can be overlapped with the original difference thickness surface to form a rectangle. In other words, after the steel plate with the different thickness surface is rotated by 180 ° in each of the horizontal direction and the vertical direction, the slope surface of the steel plate can be attached to the slope surface of another steel plate with the same different thickness surface, and the two steel plates are stacked to form a rectangular parallelepiped, i.e., a stacked different thickness steel plate, as shown in fig. 2.
In the figure, 1 and 2 are the two different thick steel plates with the same shape and size, 11 and 21 are the different thick surfaces of the two steel plates, once one of the two steel plates rotates 180 degrees in the horizontal direction and the vertical direction, the slope surface can be attached to the slope surface of the other steel plate with the same section, the two steel plates are overlapped to form a cuboid, namely a overlapped different thick steel plate, Wz and Lz are the width and the length of the overlapped different thick steel plate respectively, Tz is the thickness of the overlapped different thick steel plate, Ta is the minimum thickness of the two different thick steel plates, and Tb is the maximum thickness of the two different thick steel plates respectively.
The sum of the maximum thickness Tb and the minimum thickness Ta of the steel plate is not more than the limit thickness of the flat quenched and tempered steel plate of the same steel type, and the width W and the length L of the steel plate can reach the normal range of the flat quenched and tempered steel plate.
The process window of quenching and tempering of the steel plate is not narrowed or even completely eliminated due to the thickness difference of the steel plate.
2) The overlapped blank designed by the invention is formed by overlapping two intermediate blanks with the same shape and size, and the intermediate blank has the following characteristics:
one of the upper surface and the lower surface is a non-horizontal plane with a slope surface (hereinafter referred to as a slope surface), and the other surface is a horizontal plane; of the cross section and the longitudinal section, a geometric shape of one section is a right trapezoid or a polygon (hereinafter referred to as a differential thickness surface) composed of a plurality of right trapezoids and rectangles, and a geometric shape of the other section is a rectangle, as shown in fig. 3. In the figure, 3 is an intermediate blank, 32 is a slope surface, 31 is a difference thickness surface, Lp and Wp are respectively the length and the width of the intermediate blank, Wp1, Wp2 and Wp3 … … are respectively the width of each width section, Ha is the minimum thickness of the blank, Hb is the maximum thickness of the blank, Hx is the thickness of the blank at a certain width position, and H1 and H2 … … are respectively the maximum thickness or the minimum thickness of the blank in each width section. The difference surface 31 is rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately displaced, and then, the difference surface and the original difference surface 31 may be stacked together to form a rectangle, and the height of the rectangle is Ha + Hb, and the width of the rectangle is Wp.
Controlling the ratio (compression ratio) of the thickness Hx of the middle blank at a certain point in the width direction to the thickness Tx of the differential thickness steel plate at a corresponding position to be 2-6 times, wherein the compression ratio of the thicker side is larger than that of the thinner side; for hot continuous rolling, steckel mills, the Wp of the intermediate blank should be greater than the width W of the finished differential thickness steel plate, in order to leave a sufficiently wide amount of cut edges; there is no such limitation in the case of a reversible wide and thick plate mill.
And thirdly, the chemical composition of the same flat quenched and tempered steel plate is similar to that of the maximum and minimum thickness sum (Tz + Tb + Ta) of the differential thickness steel plate.
3) The intermediate blank designed by the invention can be produced by adopting the following process:
directly casting the steel ingot with the different thickness surface shown in the figure 3 by utilizing the processes of die casting and the like;
or rolling the billet into the cogging stock with the differential thickness surface shown in the figure 3 by using a cuboid blank such as a continuous casting billet and the like through a wide and thick plate rolling mill to change the thickness longitudinally.
4) The overlapped blank designed by the invention is formed by overlapping and welding two intermediate blanks by adopting the following steps:
the surface treatment of the slope surfaces of the two intermediate blanks, such as flattening, cleaning and the like, is carried out, and surface defects such as cracks, slag inclusion, pits and the like which are visible to naked eyes and high-temperature iron oxide scales are removed. If necessary, the slope surface should be ground, shot-blasted and the like to ensure that the finished poor-thickness steel plate can obtain good surface quality.
Beveling the peripheries of the two middle blanks, smearing or covering a separant on the slope surface of one of the two blanks, rotating the other blank by 180 degrees in the horizontal direction and the vertical direction respectively, and then attaching the slope surface of the other blank to the slope surface of the blank smeared or covered with the separant to form a laminated blank;
thirdly, the overlapped blank is welded discontinuously along the middle groove gap, as shown in fig. 4. In the figure, 3 and 4 are two intermediate blanks after surface treatment and groove processing respectively, 5 is a welding seam for performing discontinuous welding along the peripheral grooves of the two intermediate blanks, 31 and 41 are different thickness surfaces of the two intermediate blanks respectively, Ha is the minimum thickness of the intermediate blank, Hb is the maximum thickness of the intermediate blank, H3x and H4x are the thicknesses of the two intermediate blanks at a certain width position respectively, and Lp, Wp and Hp are the length, width and thickness of a superposed blank formed by superposing and welding the two intermediate blanks respectively. In consideration of release agent and other factors, the thickness of the laminated blank should be slightly larger than the sum of the maximum thickness and the minimum thickness of the two intermediate blanks, i.e. Hp > (Ha + Hb) ═ H3x + H4 x.
In order to improve the production efficiency, the laminated blanks can be combined in a length direction in a multiple-length mode, or in a width direction in a multiple-width mode to form a laminated blank with a larger single weight and multiple-length or multiple-width.
5) The laminated slab designed by the present invention is a laminated slab as shown in fig. 2, which is heated, rolled and straightened by the same heating, rolling and straightening processes as those of a flat quenched and tempered steel sheet of the same steel type, and the thickness Tz of the laminated slab is made larger than the sum of the maximum thickness and the minimum thickness of the slab, the width Wz thereof is made larger than the width W of the slab (larger than a multiple of W in the case of double width rolling), and the length Lz thereof is made larger than the length L of the slab (larger than a multiple of L in the case of double length rolling).
6) Carrying out necessary hot straightening and cold straightening on the superposed differential thick steel plate by adopting the existing mature technology, and sending the superposed differential thick steel plate into a quenching heat treatment furnace and a quenching machine for quenching treatment through hoisting equipment such as a travelling crane and a roller way before trimming and sizing; the quenching process of the differential thickness steel plate is the same as that of a flat steel plate of the same steel type except for quenching time parameters such as furnace time, heat preservation time and the like; during quenching treatment:
the furnace time is A, Tz (min), and the heat preservation time is B, Tz (min);
wherein A is the thickness coefficient of the in-furnace time, and A is 1.8-4.0 (min/mm);
b is a heat preservation time thickness coefficient, and B is 1.2-3.0 (min/mm);
tz is the thickness of the laminated steel plate, and the unit is mm;
7) conveying the overlapped differential thick steel plate into a tempering heat treatment furnace for tempering treatment through lifting equipment such as a travelling crane and a roller way; except tempering heat treatment parameters such as furnace time, heat preservation time and the like, the tempering process of the differential thickness steel plate is the same as that of a flat steel plate of the same steel type; and (3) tempering:
the furnace time is A, Tz (min), and the heat preservation time is B, Tz (min);
wherein A is a furnace time thickness coefficient, and A is 2.5-8.0 (min/mm);
b is a heat preservation time thickness coefficient, and B is 1.5-7.0 (min/mm);
the thickness of the Tz laminated steel plate is in mm;
8) and (3) trimming and sizing the quenched and tempered superposed steel plate, namely cutting off the width allowance and the length allowance of the superposed steel plate, and separating the upper layer steel plate and the lower layer steel plate to finally obtain two transverse thickness-difference quality-adjusting steel plates with required dimension specifications shown in the figure 1. Under the condition of multiple length or multiple width, more than 4 transverse thickness difference adjustable steel plates are obtained.
Example 1
In the embodiment, a 06Ni9DR wide quenched and tempered steel plate with transversely variable thickness and a preparation process thereof are designed for a 06Ni9DR quenched and tempered steel plate for the 3 lowest tank walls of a large LNG storage tank.
In the existing design, the sizes of the 4 layers of the 06Ni9DR quenched and tempered steel plates at the lowest part are respectively as follows:
layer 1: 27X 2980X 12000 mm;
layer 2: 23X 2980X 12000 mm;
layer 3: 19X 2980X 12000 mm;
layer 4: 15X 2980X 12000 mm.
Therefore, on the premise of ensuring that the bearing capacity is not reduced, the embodiment designs two transverse differential thickness modulation plates for the lowest 3 layers of steel plates, and the dimensional specifications are as follows:
new layer 1: (22-27) X4470X 12000 mm;
new 2 layers: (17-22) 4470X 12000 mm.
As shown in fig. 1. In the figure, 1 is a transverse differential thickness temper steel plate, 11 is a differential thickness surface, 12 is a slope surface, W is the width of the differential thickness steel plate, W1, W2 and W3 … … are the width of each width section respectively, L is the length of the differential thickness steel plate, Ta is the minimum thickness of the steel plate, Tb is the maximum thickness of the steel plate, T1 and T2 … … are the maximum plate thickness or the minimum plate thickness of each width section of the steel plate respectively, and Tx is the thickness of a certain position of the steel plate. The differential thickness surface 11 is rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately displaced, and then the differential thickness surface and the original differential thickness surface 11 are stacked together to form a rectangular parallelepiped, and the height of the rectangular parallelepiped is Ta + Tb, and the width of the rectangular parallelepiped is W.
Taking a new 1-layer differential thick steel plate as an example, the manufacturing process is explained as follows:
the thickness difference is 5mm, the difference thickness ratio is 1.27:1, and the full-board width difference thickness ratio is 1: 894. Ta + Tb 49mm, not greater than the ultimate thickness of a flat 06Ni9DR steel sheet (typically, the ultimate thickness of an equal thickness 06Ni9DR quenched and tempered steel sheet is 50 mm).
To produce the new 1-layer quenched and tempered steel plate, an intermediate blank with a difference in thickness in the transverse direction or the longitudinal direction is prepared. The intermediate blank can be a die-cast slab ingot, but considering that the width-thickness ratio of the slab ingot under the steel plate specification is large, the trimming amount caused by the width taper is also large, and the production efficiency and the yield are both low, therefore, a common continuous casting blank is preferably selected and rolled into the intermediate blank shown in the figure 3 by the existing longitudinal thickening rolling technology. In fig. 3, the center blank is 32, the slope surface is 31, the differential thickness surface is 31, Lp and Wp are respectively the length and width of the center blank, W is the width of the differential thickness steel plate, W0 is the trimming margins on the left and right sides, Wp1, Wp2 and Wp3 … … are respectively the width of each width section, Ha is the minimum thickness of the blank, Hb is the maximum thickness of the blank, Hx is the thickness of the blank at a certain width position, and H1, H2 and … … are respectively the maximum thickness or the minimum thickness of the blank in each width section. The difference surface 31 may be formed into a rectangular parallelepiped by being rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately shifted, and then the height Ha + Hb and the width Wp of the rectangular parallelepiped may be stacked on the original difference surface 31.
For the intermediate blank of the new 1-layer differential thick steel plate: lp 4300mm, Wp 4630mm, W4470 m, W0 mm 80mm on the thicker side, set the compression ratio to 6, that is, Hb 2mm 162 mm; the compression ratio on the thinner side is set to 5.8, i.e., Ha-H1-128 mm. Hx is the thickness of the blank at a certain width position, and the ratio of Hx to the thickness Tx of the steel plate at the corresponding position is set to be 5.8 to 6.
The chemical composition of the intermediate blank of the new 1-layer differential thick steel plate is the chemical composition of a flat 06Ni9DR steel plate with the thickness of about 49 mm.
The two intermediate blanks are subjected to shot blasting treatment and groove processing, a parting agent is coated on the slope surface of one of the two intermediate blanks, the other intermediate blank is turned over by 180 degrees and is aligned and overlapped with the former, and finally the two intermediate blanks are welded intermittently along the grooves of the two blanks to form a overlapped blank shown in figure 4. In the figure, 3 and 4 are two intermediate blanks after surface treatment and groove processing respectively, 5 is a discontinuous welding seam between the two intermediate blanks, 31 and 41 are different thickness surfaces of the two intermediate blanks respectively, Ha is the minimum thickness of the intermediate blank, Hb is the maximum thickness of the intermediate blank, and Hp is the thickness of the overlapped blank. Considering the factors of a separating agent and the like, Hp is larger than Ha + Hb, H3x and H4x are the thicknesses of the two middle blanks at certain width positions respectively, Lp, Wp and Hp are the length, the width and the thickness of the two middle blanks which are welded into a laminated blank in an overlapping mode respectively, W is the width of a steel plate, and W0 is the margin of trimming.
For the new 1-layer differential thick steel plate laminated blank, W is 4470mm, WP is 4630mm, LP is 4300mm, Hb is 162mm, Ha is 128mm, Hp is 292mm > Ha + Hb.
The laminated blank is heated by a continuous heating furnace by the existing heating process, and then rolled into the laminated differential thick steel plate shown in figure 2 by a 5000mm wide thick plate rolling mill by the existing rolling process of a flat 06Ni9DR steel plate. In the figure, 1 and 2 are the double-length steel plates of two transverse differential thick steel plates, 11 and 21 are the differential thick surfaces of the two differential thick steel plates, Wz, Lz and Tz are the width, length and thickness of the superposed differential thick steel plates, Ta is the minimum thickness of the differential thick steel plates, Tb is the maximum thickness of the differential thick steel plates, and T1x and T2x are the thicknesses of the two steel plates at certain width positions. In this embodiment, Ta is 22mm, Tb is 27mm, Wz is 4630mm, Lz is 25800mm, two times larger than 12000mm, Tz is 50mm, and slightly larger than Ta + Tb is 49 mm.
The superposed differential thick steel plate is conveyed into a quenching heat treatment furnace and a quenching machine for quenching treatment through lifting equipment such as a travelling crane, a roller way and the like before necessary hot straightening and cold straightening, trimming and sizing are carried out by adopting the prior mature technology.
The quenching process of the differential thickness steel plate is the same as the quenching process of the flat 06Ni9DR steel plate with similar thickness except for the quenching and tempering time parameters such as the furnace time, the heat preservation time and the like. During quenching treatment, the furnace time and the heat preservation time of the differential thickness steel plate depend on the thickness Tz of the laminated steel plate, which is 50 mm:
the furnace time is A and 50(min), and the heat preservation time is B and 50 (min);
taking 2.3% of A and 1.8% of B, and then taking 115(min) of quenching time in the furnace and 90(min) of heat preservation time;
and conveying the laminated steel plate into a tempering heat treatment furnace for tempering treatment through lifting equipment such as a travelling crane and a roller way.
Except tempering heat treatment parameters such as furnace time, heat preservation time and the like, the tempering process of the differential thickness steel plate is the same as that of a flat 06Ni9DR steel plate with similar thickness. In the tempering treatment, the furnace time and the heat preservation time of the differential thickness steel plate depend on the thickness Tz of the laminated steel plate is 50 mm:
the furnace time is A and 50(min), and the heat preservation time is B and 50 (min);
taking A as 2.8 and B as 2.0; then the tempering furnace time is 140(min), and the heat preservation time is 100 (min);
and (3) trimming and sizing the quenched and tempered superposed steel plate, namely cutting off the width allowance and the length allowance of the superposed steel plate, and separating the upper layer steel plate and the lower layer steel plate to finally obtain 4 transverse thickness-difference quality-adjusting steel plates with required dimension specifications shown in the figure 1.
For the new 2-layer differential thick steel plate, the basic manufacturing process is basically the same as that of the new 1-layer differential thick steel plate, and only the following differences exist:
Ta-T2-17 mm, Tb-T1-22 mm, thickness difference of 5mm, thickness difference ratio of 1.38:1, and full width difference thickness ratio of 1: 894. Ta + Tb 39 mm;
the maximum thickness of the intermediate billet is Hb (H2) ═ 22 × 6 ═ 132mm, the minimum thickness is Ha (H1) ═ 17 × 6 ═ 93mm, the length Lp of the laminated billet is 4300mm, the width Wp of the laminated billet is 4630mm, and the thickness Hp of the laminated billet is 226 mm; the quenching time of a laminated steel plate made of the laminated blank is 87(min), and the heat preservation time is 68 (min); the tempering in-furnace time of the laminated steel plate is 106(min), and the heat preservation time is 76 (min).
Compared with the existing steel plate design of 06Ni9DR quenched and tempered steel plates for the lowest 3 layers of tank walls of large-scale LNG storage tanks, the differential thickness steel plate designed in the embodiment and the manufacturing method thereof have the advantages that:
1) in the embodiment, only 2 steel plates are used, the sum of the single weights is 18.527 tons, 3 steel plates in the original design are replaced, the sum of the single weights is 19.369 tons, and the steel can be saved by 4.35 percent, namely the dead weight is reduced by 4.35 percent. Meanwhile, 3 tailor-welded blanks are replaced by 2 differential thick steel plates, and 1 welding seam is reduced.
2) In the embodiment, the existing heating, steel rolling, straightening, quenching furnace, quenching machine, tempering furnace, hoisting and other equipment are utilized, and the mature heating, rolling, straightening, quenching and tempering heat treatment processes are adopted, so that the transverse thickness-difference quality-adjusting steel plate can be economically produced in batches.
3) The manufacturing method provided by the embodiment can not generate the limit of the process window of quenching and tempering heat treatment due to the thickness difference of the steel plate.
4) The width and length of the differential thickness steel plate in the embodiment reach the normal range of a flat quenched and tempered steel plate, for example, the maximum width can reach 4470mm, and the maximum length (multiple length) can reach 24000 mm.
Example 2
In the embodiment, a transverse variable-thickness A514Gr.F wide quenched and tempered steel plate and a preparation process thereof are designed for the A514Gr.F quenched and tempered steel plate for a certain ocean platform structure.
In the existing design, the ocean platform structure needs to be formed by welding three A514Gr.F quenched and tempered steel plates with the same width and length but different thicknesses, and the size specifications of the quenched and tempered steel plates are 50 multiplied by 1460 multiplied by 10000mm, 45 multiplied by 1460 multiplied by 10000mm and 40 multiplied by 1460 multiplied by 10000mm respectively. In fact, according to the load condition borne by the platform, the A514Gr.F wide-width quenched and tempered steel plate which has the width of 4380mm, the length of 10000mm, the thickness of 50mm and 35mm can be completely adopted theoretically, and the thickness of the quenched and tempered steel plate is gradually reduced along the width direction.
Therefore, in the embodiment, one transverse thickness difference modulation plate A514Gr.F is designed for the 3 steel plates with different thicknesses, the dimension specification is (35-50) × 4380 × 10000mm, the maximum thickness difference of the whole plate is 15mm, and the maximum thickness difference ratio is 1.43: 1. As shown in fig. 5, 1 is a transverse differential thickness steel plate, 11 is a differential thickness surface, 12 is a slope surface, W is a width of the differential thickness steel plate, L is a length of the differential thickness steel plate, Ta is a minimum thickness of the steel plate, Tb is a maximum thickness of the steel plate, and Tx is a thickness of the steel plate at a certain width position. The differential thickness surface 11 is rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately displaced, and then the differential thickness surface and the original differential thickness surface 11 are stacked together to form a rectangular parallelepiped, and the height of the rectangular parallelepiped is Ta + Tb, and the width of the rectangular parallelepiped is W.
In this example, W is 4380mm, L is 10000mm, and Ta is 35 mm; tb is 50mm, the thickness difference is 15mm at most, the difference thickness ratio is 1.43:1, and the difference thickness ratio is 1: 292. Ta + Tb 85mm, not greater than the ultimate thickness of an equal thickness steel sheet of 514gr.f (normally, the ultimate thickness of an equal thickness, 514gr.f quenched and tempered steel sheet is 100 mm).
To produce the above-described differential thickness steel sheet, an intermediate blank having a differential thickness in the transverse or longitudinal direction is first prepared. In this embodiment, a common continuous casting slab is selected and rolled into an intermediate slab as shown in fig. 6 by the existing longitudinal thickening rolling technology. In fig. 6, 3 is the middle blank, 32 is the slope surface, 31 is the differential thickness surface, Lp and Wp are the length and width of the middle blank respectively, W is the width of the differential thickness steel plate, W0 is the trimming margins on the left and right sides, Ha is the minimum thickness of the blank, and Hb is the maximum thickness of the blank. The difference surface 31 may be formed into a rectangular parallelepiped by being rotated by 180 ° in each of the horizontal direction and the vertical direction and appropriately shifted, and then the height Ha + Hb and the width Wp of the rectangular parallelepiped may be stacked on the original difference surface 31.
In this embodiment, Lp is 4500mm, Wp is 4540mm, W is 4380m, and W0 is 80mm, and the compression ratio on the thicker side is set to 5, that is, Hb is 250 mm; the compression ratio on the thinner side was set to 4.8, i.e., Ha ═ 168 mm. Hx is the thickness of the blank at a certain width position, and the ratio of Hx to the thickness Tx of the steel plate at the corresponding position is set to be 4.8 to 5.
The chemical composition of the intermediate blank is that of an A514Gr.F steel plate which is about 85mm thick and flat.
The two intermediate blanks are subjected to shot blasting treatment and groove processing, a parting agent is coated on the slope surface of one of the two intermediate blanks, then the other intermediate blank is turned over by 180 degrees and is aligned and overlapped with the former, and finally the two intermediate blanks are welded intermittently along the grooves of the two blanks to form a overlapped blank shown in figure 7. In the figure, 3 and 4 are two intermediate blanks after surface treatment and groove processing respectively, 5 is a discontinuous welding seam between the two intermediate blanks, 31 and 41 are different thickness surfaces of the two intermediate blanks respectively, Ha is the minimum thickness of the intermediate blank, Hb is the maximum thickness of the intermediate blank, H3x and H4x are the thicknesses of the two intermediate blanks at a certain width position respectively, and Lp, Wp and Hp are the length, width and thickness of the two intermediate blanks which are overlapped and welded into an overlapped blank respectively. In this example, Ha is 168mm, Hb is 250mm, and Hp is greater than Ha + Hb in consideration of a spacer and the like, and hence Hp is 420mm, Wp is 4540mm, and Lp is 4500 mm.
The laminated blank is heated by a continuous heating furnace by the existing heating process, and then rolled into the laminated differential thick steel plate shown in the figure 8 by a 5000mm wide thick plate rolling mill by the existing rolling process of a flat A514Gr.F steel plate. In the figure, 1 and 2 are the double-length steel plates of two transverse differential thick steel plates, 11 and 21 are the differential thick surfaces of the two differential thick steel plates, Wz, Lz and Tz are the width, length and thickness of the superposed differential thick steel plates, Ta is the minimum thickness of the differential thick steel plates, Tb is the maximum thickness of the differential thick steel plates, and T1x and T2x are the thicknesses of the two steel plates at certain width positions. In this embodiment, Ta is 35mm, Tb is 50mm, Wz is 4540mm, Lz is 22500mm, a length twice as large as 12000mm, Tz is 86mm, and a length slightly larger than Ta + Tb is 85 mm.
The steel plate is sent into a quenching heat treatment furnace and a quenching machine for quenching treatment before necessary hot straightening, cold straightening, trimming and sizing.
The quenching process of the differential thickness steel plate is the same as the quenching process of the A514Gr.F steel plate with similar thickness except for quenching and tempering time parameters such as furnace time, heat preservation time and the like. In the quenching treatment, the furnace time and the heat preservation time of the differential thickness steel plate depend on the thickness Tz of the laminated steel plate to be 89 mm:
the furnace time is A x 86(min), and the heat preservation time is B x 86 (min);
taking A as 2.3 and B as 1.8, then the furnace time of quenching is 198(min), and the heat preservation time is 156 (min);
and (4) feeding the laminated steel plate into a tempering heat treatment furnace for tempering treatment.
Except tempering heat treatment parameters such as furnace time, heat preservation time and the like, the tempering process of the differential thickness steel plate is the same as that of the A514Gr.F steel plate with similar thickness. In the tempering treatment, the furnace time and the heat preservation time of the differential thickness steel plate depend on the thickness Tz of the laminated steel plate to be 89 mm:
the furnace time is A x 86(min), and the heat preservation time is B x 86 (min);
taking A as 2.8 and B as 2.0; then the tempering furnace time is 241(min), and the heat preservation time is 172 (min);
and (3) trimming and sizing the quenched and tempered laminated steel plate, namely cutting off the width allowance and the length allowance of the laminated steel plate, and separating an upper layer steel plate and a lower layer steel plate to obtain four A514Gr.F quenched and tempered steel plates with the size specification of (35-50) multiplied by 4380 multiplied by 10000mm for the ocean platform structure.
Compared with the existing design of the A514Gr.F quenched and tempered steel plate for the ocean platform structure, the differential thick steel plate designed in the embodiment and the manufacturing method thereof have the advantages that:
1) in the embodiment, only 1 steel plate is used, the single weight is 15.472 tons, 3 steel plates in the original design are replaced, the sum of the single weights is 14.613 tons, and the steel can be saved by 5.56 percent, namely the dead weight is reduced by 5.56 percent. Meanwhile, 3 tailor-welded blanks are replaced by 1-piece differential thick steel plate, and 2 welding seams are reduced.
2) In the embodiment, the existing heating, steel rolling, straightening, quenching furnace, quenching machine, tempering furnace, hoisting and other equipment are utilized, and the mature heating, rolling, straightening, quenching and tempering heat treatment processes are adopted, so that the transverse thickness-difference quality-adjusting steel plate can be economically produced in batches.
3) The manufacturing method provided by the embodiment can not generate the limit of the process window of quenching and tempering heat treatment due to the thickness difference of the steel plate.
4) The width and length of the differential thickness steel plate in the embodiment reach the normal range of a flat quenched and tempered steel plate, for example, the maximum width can reach 4380mm, and the maximum length (multiple length) can reach 20000 mm.
Claims (4)
1. A transversely variable thickness wide width quenched and tempered steel plate is characterized in that the thickness of the steel plate is monotonously and linearly increased or decreased in sections in the width direction; one of the upper and lower surfaces of the steel plate is a slope surface which is a non-horizontal surface with sectional inclination, and the other surface is a horizontal surface; the longitudinal section of the steel plate is rectangular, the cross section of the steel plate is a right trapezoid or consists of a plurality of right trapezoids and a rectangle, after one steel plate with the section is rotated by 180 degrees in the horizontal direction and the vertical direction, the slope surface of the steel plate can be attached to the slope surface of the other steel plate with the same section, and the two steel plates are overlapped to form a cuboid, namely a overlapped differential thick steel plate; the difference between the maximum plate thickness and the minimum plate thickness of the steel plate is not more than 15mm, the ratio of the maximum plate thickness to the minimum plate thickness is not more than 2:1, and the ratio of the difference between the maximum plate thickness and the minimum plate thickness to the width is not more than 1: 200.
2. The method for manufacturing a transversely variable thickness quenched and tempered steel sheet as claimed in claim 1, comprising the steps of:
1) preparation of superimposed blanks
The device is formed by overlapping two intermediate blanks with the same shape and size, wherein one of the upper surface and the lower surface of the intermediate blank is a non-horizontal plane with a slope surface, namely a slope surface, while the other surface is a horizontal plane; among the cross section and the longitudinal section, the geometric shape of one section is a right trapezoid or a polygon formed by a plurality of right trapezoids and rectangles, namely a differential thickness surface, and the geometric shape of the other section is a rectangle; the ratio of the thickness Hx of the middle blank at a certain point in the width direction to the thickness Tx of the finished differential thickness steel plate at the corresponding position, namely the compression ratio, is controlled to be 2-6 times, wherein the compression ratio of the thicker side is larger than that of the thinner side; for hot continuous rolling and steckel rolling mills, the width Wp of the intermediate blank is greater than the width W of the finished product differential thick steel plate, and the reversible wide and thick plate rolling mill has no limitation;
2) the slope surfaces of the two intermediate blanks are flattened and subjected to surface cleaning treatment to remove macroscopic cracks, slag inclusions, pit surface defects and high-temperature iron scales, so that the finished poor-thickness steel plate is ensured to obtain good surface quality;
3) the peripheries of the two middle blanks are subjected to groove processing, and a slope surface of one of the two blanks is coated or covered with a separant; after the other blank is rotated by 180 degrees in the horizontal direction and the vertical direction respectively, the slope surface of the other blank is jointed with the slope surface of the blank coated or covered with the separant to form a superposed blank;
4) carrying out discontinuous welding on the superposed blank along the middle groove gap;
5) manufacture of differential thickness steel plate
Heating, rolling and straightening the superposed blank by the same heating, rolling and straightening processes as those of a flat quenched and tempered steel plate of the same steel type to obtain a superposed differential thick steel plate, wherein the thickness Tz of the superposed differential thick steel plate is larger than the sum of the maximum thickness and the minimum thickness of the differential thick steel plate, the width Wz of the superposed differential thick steel plate is larger than the width W of the differential thick steel plate, and the length Lz of the superposed differential thick steel plate is larger than the length L of the differential thick steel plate;
carrying out necessary hot straightening and cold straightening on the overlapped differential thick steel plate by adopting the existing mature technology, and before trimming and sizing, conveying the steel plate into a quenching heat treatment furnace and a quenching machine through lifting equipment for quenching treatment; the quenching process of the differential thickness steel plate is the same as that of a flat steel plate of the same steel type except for the in-furnace time and the heat preservation time; during quenching treatment:
the furnace time is A Tz, the heat preservation time is B Tz, and the unit of min is obtained;
wherein A is a furnace time thickness coefficient, and is 1.8-4.0 in unit of min/mm;
b is a heat preservation time thickness coefficient, and the unit min/mm is 1.2-3.0;
tz is the thickness of the laminated steel plate and the unit mm;
6) conveying the overlapped differential thick steel plate into a tempering heat treatment furnace for tempering treatment through lifting equipment; except for the furnace time and the heat preservation time, the tempering process of the differential thickness steel plate is the same as that of the flat steel plate of the same steel type; and (3) tempering:
the furnace time is A Tz, the heat preservation time is B Tz, and the unit of min is obtained;
wherein A is a furnace time thickness coefficient, and A is 2.5-8.0, unit min/mm;
b is a heat preservation time thickness coefficient, and the unit min/mm is 1.5-7.0;
tz is the thickness of the laminated steel plate and the unit mm;
7) and (3) trimming and sizing the quenched and tempered superposed steel plate, namely cutting off the width allowance and the length allowance, and separating the upper layer steel plate and the lower layer steel plate to finally obtain two transverse thickness-difference quality-adjusting steel plates with required dimension specifications.
3. The method for manufacturing a transversely variable-thickness wide quenched and tempered steel plate as claimed in claim 2, wherein the intermediate slab is directly cast into a steel ingot with the differential thickness surface by a die casting process; or a rectangular blank is obtained by a continuous casting process, and is rolled into an cogging material with the differential thickness surface by longitudinally changing the thickness of the rectangular blank through a wide and thick plate rolling mill.
4. The method for manufacturing a transversely variable thickness quenched and tempered steel sheet as claimed in claim 2, wherein in step 3), the laminated blank is combined in multiple sizes in the longitudinal direction or in multiple sizes in the width direction to form a laminated blank of a larger single weight in multiple sizes or multiple widths.
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| JPS58187228A (en) * | 1982-04-24 | 1983-11-01 | Kobe Steel Ltd | Manufacture of metallic plate having different thickness in width direction |
| CN107999536A (en) * | 2017-12-20 | 2018-05-08 | 东北大学 | A kind of ply rolling method that horizontal Varying Thickness Plates band is prepared using point-symmetry property |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58187228A (en) * | 1982-04-24 | 1983-11-01 | Kobe Steel Ltd | Manufacture of metallic plate having different thickness in width direction |
| CN107999536A (en) * | 2017-12-20 | 2018-05-08 | 东北大学 | A kind of ply rolling method that horizontal Varying Thickness Plates band is prepared using point-symmetry property |
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