Strain-hardened floor plates and method of manufacture

Abstract

Floor plates and methods of manufacturing floor plates are presented herein. The method including hot rolling a steel slab in one or more hot rolling passes into a steel coil or plate, annealing the steel coil or plate after the hot rolling into an annealed steel coil or plate, and cold rolling or temper rolling the annealed steel coil or plate into the floor plate in one or more cold rolling or temper rolling passes of a rolling apparatus, wherein the rolling apparatus includes a top roller and a bottom roller and is structured to achieve a desired lug pattern and height with a gauge reduction using either hot-rolled and / or annealed steel.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No. 63 / 730,298, filed on Dec. 10, 2024, and titled “STRAIN-HARDENED FLOOR PLATES AND METHOD OF MANUFACTURE,” the entirety of which is incorporated by reference herein.TECHNOLOGICAL FIELD

[0002] The present disclosure relates to floor plates and methods of manufacturing floor plates.BACKGROUND

[0003] In conventional floor plate designs, the lugs formed on the plate surface often exhibit deficiencies resulting from production processes. Specifically, the lugs may soften during production, resulting in insufficient surface hardness and reduced durability. Additionally, surface decarburization frequently occurs, which further compromises the structural integrity and performance of the lugs. These factors collectively contribute to low yield strength, inadequate slip resistance, poor wear resistance, and an undesirable surface finish. Such shortcomings significantly limit the functionality and longevity of floor plates in demanding applications. Thus, there is a need for a method for producing floor plates with improved anti-slip, abrasion, and mechanical properties.BRIEF SUMMARY

[0004] The present disclosure relates to converting hot rolled steel (e.g., hot bands, hot-rolled plates, or the like) into floor plates, also known as steel diamond plate, checkered plate and tread plate. By introducing patterned work rolls in mills with a gauge reduction under stress-relieving temperatures, both surface texture and strain hardening may be achieved simultaneously through temper rolling or cold rolling processes for both carbon steel plates and high-strength and low-alloy floor steel plates. The cold (i.e., below room temperature) or warm (i.e., above room temperature, but below the stress-relieving temperature) deformation in the steel generates a permanent change to the crystalline structure of the metal, which improves the patterns for 4-way slip resistance, improves the mechanical properties of the plates, increases the hardness of lugs, and creates a finished surface. These features can be utilized to design lightweight deck structures, increase lug durability, and enable the floor plates to withstand heavy traffic.

[0005] In one aspect of the present disclosure, a method of manufacturing a floor plate is provided. The method may include cold rolling or temper rolling a hot rolled or annealed steel into the floor plate in one or more cold rolling passes or one or more temper rolling passes of a rolling apparatus, wherein the rolling apparatus may include a first roller and a second roller and is structured to form a plurality of lugs in the floor plate while achieving a gauge reduction in the floor plate of between 2% and 20%.

[0006] In some implementations, the cold rolling or the temper rolling is performed under stress-relieving temperatures of less than 675° C.

[0007] Additionally, or alternatively, in some implementations, the hot rolled steel may include 0.035-0.25 weight % carbon, 0.25-1.35 weight % manganese, with optional microalloy additions of one or more of vanadium (0.005-0.15 weight %), niobium (0.005-0.050 weight %), or titanium (0.005-0.040 weight %), and a remainder of iron and unavoidable impurities.

[0008] Additionally, or alternatively, in some implementations, the hot rolled or annealed steel may further include optional alloy additions of one or more of copper (0.20-0.40 weight %), nickel (0.20-0.50 weight %), or chrome (0.20-0.40 weight %).

[0009] Additionally, or alternatively, in some implementations, one of the first roller or the second roller may include a pattern, the pattern structured to form a plurality of lugs on the floor plate including lug heights ranging from between 0.5 mm and 0.9 mm.

[0010] Additionally, or alternatively, in some implementations, the hot rolled steel has a thickness between 4.50 mm and 31.75 mm, regardless of a minimum width and a maximum width of the hot rolled steel, prior to the cold rolling or the temper rolling.

[0011] Additionally, or alternatively, in some implementations, a plurality of notches of the first roller or the second roller defines the pattern, and wherein at least one of the plurality of notches has a depth of between 0.75 mm and 2 mm.

[0012] Additionally, or alternatively, in some implementations, at least one of the first roller and the second roller has a diameter of between 400 mm and 800 mm.

[0013] Additionally, or alternatively, in some implementations, the method may further include melting one or more charges of materials in an electric arc furnace into molten steel, and casting the molten steel into the steel slab.

[0014] Additionally, or alternatively, in some implementations, the method may further include hot rolling a steel slab in one or more hot rolling passes into a hot rolled steel, and annealing the steel between or after the one or more hot rolling passes into an annealed hot rolled steel.

[0015] In another aspect of the present disclosure, a floor plate is provided. The floor plate may include a base portion including a steel plate having a top surface and a bottom surface, a plurality of lugs extending from at least one surface of the steel plate, wherein the plurality of lugs are arranged to form a pattern, and wherein the plurality of lugs may include lug heights ranging from between 0.5 mm and 0.9 mm.

[0016] In some implementations, the steel plate may include 0.035-0.25 weight % carbon, 0.25-1.35 weight % manganese, with optional microalloy additions of one or more of vanadium (0.005-0.15 weight %), niobium (0.005-0.050 weight %), or titanium (0.005-0.040 weight %), and a remainder of iron and unavoidable impurities.

[0017] Additionally, or alternatively, in some implementations, the steel plate may further include optional alloy additions of one or more of copper (0.20-0.40 weight %), nickel (0.20-0.50 weight %), or chrome (0.20-0.40 weight %).

[0018] Additionally, or alternatively, in some implementations, the plurality of lugs are formed from cold rolling or temper rolling a hot rolled or annealed steel into the floor plate in one or more cold rolling passes or one or more temper rolling passes of a rolling apparatus, wherein the rolling apparatus may include a first roller and a second roller and is structured to form the plurality of lugs in the floor plate while achieving a gauge reduction in the floor plate of between 2% and 20%.

[0019] Additionally, or alternatively, in some implementations, the cold rolling or temper rolling is performed under stress-relieving temperatures of less than 675° C.

[0020] Additionally, or alternatively, in some implementations, the hot rolled or annealed steel has a thickness between 4.50 mm and 31.75 mm, regardless of a minimum width and a maximum width of the hot rolled steel, prior to being cold rolled or temper rolled.

[0021] Additionally, or alternatively, in some implementations, a plurality of notches of the first roller or the second roller defines the pattern, and wherein at least one of the plurality of notches has a depth of between 0.75 mm and 2 mm.

[0022] Additionally, or alternatively, in some implementations, the floor plate has a tensile strength of between 53 ksi and 95 ksi.

[0023] Additionally, or alternatively, in some implementations, the floor plate has a yield strength between 36 ksi and 85 ksi.

[0024] Additionally, or alternatively, in some implementations, the floor plate has an elongation percentage at a 2-inch gauge of between 12% and 40%.

[0025] Implementations of the present disclosure include textured steel plates with improved anti-slip, abrasion-resistant, and mechanical properties, and improved methods of manufacturing such textured steel plates. The improved method employs strain hardening (otherwise described as cold working or work hardening) under stress-relieving temperatures, such as through temper rolling or cold rolling processes, to improve plate strength, improve surface finish, and increase surface hardness for abrasion resistance. The improved floor plates, and the manufacturing thereof, may result in cost savings due at least in part to the reduction in the use of raw materials (e.g., scrap steel, direct reduced iron (DRI), iron ore, or the like) and / or alloying materials, and / or reduced manufacturing steps and / or manufacturing times for the production of the improved textured steel plate.

[0026] As will be described in further detail herein, the aspects of the improved textured steel plates and the improved methods of manufacturing described herein offers advantages over traditional floor plates formed from traditional hot-rolling and / or cold-stamping processes.

[0027] For example, the aspects of the present disclosure result in less surface wear of the floor plates. In traditional plates and methods, decarburization occurs during the reheating process (e.g., when slabs are reheated and hot-rolled). This typically results in a decarburization layer on the floor plates that is between 0.2 mm and 0.5 mm thick. The reduced carbon content in this decarburization layer leads to less formation of pearlite and microalloy carbide, decreasing surface hardness and abrasion resistance of the floor plates. Under the stress-relieving temperatures and cold / warm reduction of the present disclosure, an increase in the surface hardness of the decarburization layer due to strain hardening may be achieved.

[0028] Moreover, the mechanical properties of the floor plates may be improved. The mechanical properties of the steel are determined by the chemical composition and processing of the steel, such as the rolling, annealing, and cooling processes (e.g., the number of passes, temperatures, and / or duration thereof). As such, the processing of the floor plate, as described herein, in particular the strain hardening described herein can improve plate strength by 10, 15, 20, 25, 30, 35, 40, 45, or the like percent, thus allowing for reduced floor plate thickness and / or lower microalloy additions while maintaining equivalent load capacity.

[0029] Cold reduction in gauge of the floor plate while forming the lugs may also result in an improved surface finish compared to floor plates having lugs formed during hot-rolling. Cold-rolled floor plates may have less scale on the surface and a more uniform appearance, which can be coated (e.g., painted, or the like) directly for improved corrosion resistance.

[0030] The manufacturing of hot rolled steel (e.g., hot bands, hot-rolled plates, or the like) into floor plates in accordance with the present disclosure typically occurs in a single cold rolling stand, which improves the flexibility of the manufacturing of the floor plates. That is, the single cold rolling stand allows for improved scheduling for the production of small order quantities and timely delivery of orders. Consequently, the processing of the present disclosure results in improved efficiency that minimizes the storage of inventory (e.g., manufacturing flexibility allows for improved order fulfillment). Alternatively, traditional hot-rolled floor plates are produced by tandem strip mills with patterned work rolls in the last stand. These types of tandem strip mills sell hot rolled patterned coils to service centers, which then level and cut the coils into sheets and / or plates for small quantity end-users, causing the mills to accumulate multiple sizes and produce them only once or several times per month, thereby resulting in larger inventories.

[0031] Tandem strip mills in the USA (or in other countries) may be able to produce floor plates up to 84 inches wide. However, temper mills may allow for the formation of floor plates that are wider than 84 inches. For example, it is recognized that many temper mills may have widths between 48 inches and 120 inches, and cold mills may have widths between 48 inches and 84 inches, although larger and smaller temper mills and cold mills outside of these ranges are contemplated. As such, the use of temper rolling may allow for the conversion of hot-rolled steel (e.g., hot bands or hot-rolled plates) into floor plates having widths that may exceed 84 inches without the need to upgrade the tandem stirp mills to produce wider floor plates.

[0032] Furthermore, converting hot rolled steel (e.g., hot bands or hot-rolled plates) to floor plates using a temper mill in a cut-to-length (CTL) line does not slow down output. That is, unlike traditional processing, the floor plates can be processed into customized lengths in-line during processing. In traditional processing, such as during a cold-stamped method of producing floor plates, the cold stamping only produces floor plates of specific lengths (e.g., the stamping process stamps plates of the same size). As such, the process of the present disclosure (e.g., forming the floor plates during cold or temper rollers continuously) allows the floor plates to be formed into the desired lengths by cutting the patterned plate after cold or temper rolling. As such, aspects of the present disclosure offers significantly greater productivity and efficiency in the production of floor plates.

[0033] To assess the feasibility and performance of the process, this disclosure provides the floor plate pattern and rolling parameters, including lug pattern design, lug height, gauge reduction, roll force, and roll torque. These parameters may be optimized to ensure the desired surface characteristics and mechanical properties of the floor plates.BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Having thus described implementations of the disclosure in general terms, reference will now be made the accompanying drawings. The components illustrated in the Figures may or may not be present in certain implementations described herein. Some implementations may include fewer (or more) components than those shown in the Figures.

[0035] FIG. 1 illustrates a projected arc length in the roll bite, in accordance with implementations of the disclosure;

[0036] FIGS. 2A-2B illustrate floor plate patterns as recommended in ASTM A786 / A786M-15, in accordance with implementations of the disclosure;

[0037] FIG. 3 illustrates a geometric shape of a raised lug and the specific rolling force, in accordance with implementations of the disclosure;

[0038] FIG. 4 illustrates a geometric relationship in an asynchronous rolling process, in accordance with implementations of the disclosure;

[0039] FIG. 5 illustrates geometric parameters of a lug based on ASTM A786 / A786M-15, in accordance with implementations of the disclosure;

[0040] FIGS. 6A-6C illustrate a front view, section view along line A-A, and perspective view of a geometric relationship between grinding wheel and work roll axes, in accordance with implementations of the disclosure;

[0041] FIG. 7 illustrates a flowchart for determining temper rolling process parameters, in accordance with implementations of the disclosure;

[0042] FIG. 8 illustrates a surface appearance of a ground work roll, in accordance with implementations of the disclosure;

[0043] FIG. 9 illustrates geometric parameters of lugs and grinding wheel, in accordance with implementations of the disclosure;

[0044] FIG. 10 illustrates chemical compositions of floor plates, in accordance with implementations of the disclosure;

[0045] FIG. 11 illustrates mechanical properties of floor plates, in accordance with implementations of the disclosure;

[0046] FIG. 12 illustrates a floor plate exiting the temper mill, in accordance with implementations of the disclosure;

[0047] FIG. 13 illustrates a sampling plan and data acquisition sheet, in accordance with implementations of the disclosure;

[0048] FIGS. 14A-14B illustrate tensile properties for sizes of floor plates based on gauge reduction rate, in accordance with implementations of the disclosure;

[0049] FIGS. 15A-15D illustrates Vickers hardness numbers for sizes of floor plates based on gauge reduction rate, in accordance with implementations of the disclosure;

[0050] FIG. 16 illustrates results of 90-degree bending tests of floor plates, in accordance with implementations of the disclosure;

[0051] FIGS. 17A-17B illustrate graphs showing the relationship between lug height and gauge reduction rate, in accordance with implementations of the disclosure;

[0052] FIGS. 18A-18B illustrate graphs depicting the relationship between lug height and yield strength for floor plates, in accordance with implementations of the disclosure;

[0053] FIG. 19 illustrates surface appearances of the material after brushing, in accordance with implementations of the disclosure;

[0054] FIG. 20 illustrates a floor plate surface, in accordance with implementations of the disclosure; and

[0055] FIG. 21 illustrates a graph depicting the relationship between the ratio of the gauge reduction occurring on the bottom surface relative to the top surface and the entry gauge of the strip.DETAILED DESCRIPTION

[0056] Implementations of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, implementations of the disclosure are shown. Indeed, the disclosure may be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. Furthermore, the ranges discussed herein are inclusive ranges.

[0057] The history of floor plate manufacturing traces back to traditional designs where elastic and uniform lugs (sometimes referred to as “studs”) were projected into floor plates to prevent slipping on stairs and floors. By the late 19th century, steel's strength and durability made it a staple in construction, leading to the systematic production of floor plates with slip-resistant patterns like checkered or tread plates.

[0058] Post-World War II economic growth increased the demand for floor plates, with technological advancements allowing for more precise designs. While the large-scale production origins of tread plates via hot rolling remain somewhat unclear, early inventors concentrated on raised pattern designs. Some ornamental tread plate designs were introduced. Later, in the 1970s, designs featuring flat-topped circular protrusions with elongated convex projections were introduced. Subsequently, traditional methods for producing continuous cast metallic sheets with patterned surfaces were developed.

[0059] In 1981, ASTM International established the ASTM A786 standard, first approved in 1980, to ensure consistent quality for steel plates with raised patterns for slip resistance. This standard encompasses hot-rolled carbon steel, low-alloy steel, high-strength low-alloy steel, and alloy steel, primarily produced through hot-rolling processes.

[0060] The late 20th century saw innovations such as high-strength, low-alloy steels and improved corrosion resistance, alongside sustainable manufacturing practices. Castrip technology then emerged and methods for producing extra-thin hot-rolled floor plates using cast strips were developed, which could produce lug heights between 0.3 mm and 0.7 mm in a floor plate of less than 1.7 mm.

[0061] ASTM A786 / A786M-15, approved in 2021, regulates the minimum lug height, patterns with tear-drop and diamond styles, and dimensional tolerances for hot-rolled floor plates. The industry trend has been towards increasing the lug height for improved slip resistance.

[0062] Most floor plates are hot-rolled; however, some may be manufactured through cold-stamping or pressing. For instance, some traditional methods introduce a cold-stamped anti-slip pattern structure for metal sheets, with lug heights ranging from 2 mm to 6 mm.

[0063] Similarly, some traditional methods result in surface finishes rather than functional surface lugs with peak-to-peak heights of less than 0.1 mm. Other traditional methods use “cold impressing” with a pair of male and female work rolls that do not involve any gauge reduction of the base plates.

[0064] Other traditional methods include manufacturing components from austenitic-induced plasticity (TWIP) or transformation-induced plasticity (TRIP / TWIP) steel, which includes deformed indentations in a matrix of ductile material using a cold rolling technique. However, these methods focus on material thickness reduction rather than providing anti-slip or abrasion-resistant properties.

[0065] Structural steel floor plates fabricated from hot-rolled steel (e.g., hot bands, hot-rolled plates, or the like) by cold-rolling or temper rolling processes according to the present disclosure may exhibit improved slip resistance, wear resistance, mechanical properties, and surface finish relative to conventional floor plates.

[0066] The cold rolling or temper rolling processes described herein utilizes gauge reduction of the steel while forming the lugs in the floor plates (e.g., in the last rolling step). As such, the cold rolling or temper roller may induce a strain-hardening effect, which may improve yield strength. By utilizing plain carbon steel and the processing of the present disclosure, the floor plates of the present disclosure offer the same or improved properties and / or a lightweight solution, that is a cost-effective alternative when compared to floor plates formed from high-strength and low-alloy steel made from traditional processing.

[0067] Floor plates produced using the cold rolling or temper rolling processes of the present disclosure may produce various lugs having various lug heights, however, in particular implementations the lugs may meet the lug height and / or shape and / or layout specifications of ASTM A786 (or ASTM A786 / A786M-00b) Pattern No. 2, Pattern No. 4, Pattern No. 5, Pattern No. 6, or the like. The processes of the present disclosure may enable the formation of a uniform slip-resistant pattern with lug heights ranging between 0.5 mm (0.020 inches) and 0.9 mm (0.035 inches), which may provide four-way slip resistance. In particular implementations, reducing lug height may lower the risk of trips and improve comfort for pedestrian traffic, while still providing for the benefits of patterned floor plates. Moreover, the cold rolling or temper rolling processes of the present disclosure may disrupt surface oxide scale, which may simplify its removal during surface preparation for coatings, offering advantages over traditional floor plate manufacturing methods. The improved processes and resulting improved floor plate products will be described in detail herein.Production of Hot Rolled Steel (Hot Bands or Hot-Rolled Plates)

[0068] The present disclosure may be directed to a method for converting hot rolled steel (e.g., steel hot bands, hot-rolled plates, or the like) into floor plates using a cold rolling or temper rolling process.

[0069] As used herein, “hot bands” may refer to steel sheets or strips that have undergone the hot rolling process and exhibit a semi-finished surface. In the context of steelmaking, hot bands typically result from the reduction of slabs at elevated temperatures in a hot rolling mill, producing material with uniform thickness and improved workability. These bands may serve as intermediate products for further processing described herein. While “hot bands” may be referred to throughout the present disclosure, it shall be appreciated that hot-rolled plates may be subjected to the processes described herein to result in the desired floor plates.

[0070] The hot rolled steel may be produced by electric arc furnaces (“EAF”), which utilize scrap steel, direct reduced iron (DRI), or other input materials to produce molten steel for further processing. While the present disclosure may typically utilize EAF processing, in other implementations of the disclosure, other types of furnaces may also be used to produce molten steel, such as blast furnaces, HIsarna processing (e.g., utilizing HImelt and / or cyclone converter furnaces (CCF)), or other types of furnaces that produce molten steel from iron containing materials.

[0071] The molten steel may be transferred to a ladle for further processing. The molten steel in the ladle may undergo alloying additions to produce the desired composition of the steel in a ladle metallurgy facility, or other like system. Moreover, the molten steel may be decarburized by removing all, or substantially all, of the oxygen from the molten steel. The decarburized process step may be performed in a vacuum degasser, argon decarburizer, or other like system.

[0072] The alloyed molten steel from the ladle may be supplied to a tundish with the molten steel and the steel is cast into slabs. After being cast, the slabs may be sent through a tunnel furnace to maintain the desired temperature of the slab or a reheating furnace to heat the slab to the desired temperature. Upon exiting the tunnel furnace or the reheating furnace, the slabs may be sent directly to the rolling mill for hot rolling. In other implementations of the disclosure, the steel may be cast into slabs, allowed to cool, and thereafter, at a later time, sent to a reheating furnace at the rolling mill before being hot rolled. In still other implementations of the disclosure, the steel may be continuously cast into a thin steel sheet and thereafter sent for further processing.

[0073] The cast slabs (or thin cast strip) may be hot rolled into in one or more hot rolling passes through one or more sets of hot rollers. To control the hardenability and yield strength of hot-rolled steel, the finishing temperature at the exit of the last rolling pass may be set between 700° C. and 900° C. After rolling, the plates or coils may be cooled to room temperature using one or more of: (i) Air Cooling (“AC”), (ii) Laminar Flow Cooling (“LFC”), and (iii) Accelerated Cooling (“ACC”). The cooling process may target a temperature range of 500° C. to 700° C., with a cooling rate of less than 40° C. per second. Additionally, the flow rate ratio of the bottom cooling water to the top cooling water may be between 1 and 5 to encourage uniform cooling and desired mechanical properties. Moreover, the steel may be heated or cooled between the hot rolling passes, such as annealed (e.g., batch annealed, continuous annealed, or the like), slow-cooled (e.g., in a box pit, or the like) after the coiling process. Moreover, steel may be pickled in order to remove scale (e.g., iron oxide) from the steel.

[0074] In another implementation of the disclosure, the process may begin by utilizing thinner steel sheets at the beginning of the process. Instead of using steel slabs and hot rolling the steel slabs in one or more hot rolling passes to the desired thicknesses, continuously cast thin steel strips (e.g., thin strip cast steel) may be utilized in order to begin the process of the present disclosure with a thinner steel sheet.

[0075] Thin strip cast steel may be manufactured in the same or similar way as described herein, except that during casting a water cooled mold that is used to solidify the molten metal. In the mold a thin shell of metal is solidified near the walls of the mold while steel in the middle of the mold remains molten. As the metal exits the mold the metal has a hard shell with a molten interior, at this point the metal is called a strand. The strand is then passed through multiple pairs of water-cooled rollers, which support and cool the strand as the molten metal within the interior of the strand solidifies. The strand may also pass through a cooling chamber that sprays cooling liquid, such as water, on the strand to help further solidify the core of the strand. The strand may pass through various rolling operations to straighten, smooth, reduce the thickness, or the like of the strand and form a coil. In some implementations of the disclosure the thin strip cast steel produced by the continuous casting process may have a thickness less than or equal to 1, 1.2, 1.5, 1.7, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10 mm, or the like mm or other thickness described herein. In other implementations of the disclosure the ranges of the thicknesses of the thin strip cast steel may be within, overlap, or fall outside of these values. The thin strip cast steel sheet may be processed in the same or similar way as previously described herein, such as pickled, annealed, or the like.

[0076] While various steels, stainless steels, steel alloys, or the like are contemplated for use in the present disclosure, structural steels (including weathering steels) for use in the floor plates described herein may have a chemical composition of between 0.035-0.25 weight % carbon and 0.25-1.35 weight % manganese, with optional microalloy additions of vanadium (0.005-0.15 weight %), niobium (0.005-0.050 weight %), and / or titanium (0.005-0.040 weight %), and optional alloy additions of copper (0.20-0.40 weight %), or nickel (0.20-0.50 weight %), and / or chrome (0.20-0.40 weight %).

[0077] In particular implementations, hot rolled steel may have a thickness between 4.50 mm to 31.75 mm (0.177 to 1.250 inches), between 4.50 mm and 10.00 mm, between 10.00 mm and 20.00 mm, or between 20.00 mm and 31.75 mm. Other ranges may include 5.00 mm to 15.00 mm, or 7.50 mm to 25.00 mm (0.984 inches), or the like. The thickness of the steel sheet after hot rolling may be within, overlap, or be outside of these ranges.Cold Rolling or Temper Rolling

[0078] A cold-rolling or temper-rolling process may be carried out using patterned work rolls in single-stand mills or single pass of tandem mills to achieve a gauge reduction of between 2% and 20%, between 4% and 18%, between 6% and 16%, between 10% and 12%, between 4% and 10%, or the like. The gauge reduction of the steel during the one or more cold rolling passes may be within, overlap, or be outside of these ranges.

[0079] The cold-rolling or temper-rolling may be performed under stress-relieving temperatures of less than 675° C. (1250° F.). In some implementations, the stress-relieving temperature may be between 300° C. and 500° C., between 400° C. and 600° C., or between 500° C. and 675° C. Other ranges may include 450° C. to 550° C., or 350° C. to 450° C., or the like, depending on the composition and desired properties of the steel. In other implementations, the temperature may be within, overlap, or be outside of these ranges.

[0080] As a result of the temper rolling or cold rolling, strain-hardening of the floor plate may occur, and surface lugs may be formed with a minimum height of 0.50 mm (0.020 inch), 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, or the like.

[0081] As will be shown in the examples herein, floor plates subjected to the cold rolling or temper rolling process may result in improved mechanical properties, including improved surface hardness, yield strength (by up to 40%), and tensile strength.

[0082] To achieve the desired gauge reduction and pattern transfer, certain roll force may be required. In temper or cold rolling, the specific roll force (force per unit width) may be higher than in hot rolling, due to the material's higher flow stress and yield strength in its cold state. To manage this increased roll force, the work rolls in temper or cold rolling mills may be designed with a smaller diameter compared to those in tandem hot strip mills. One potential concern may be whether the temper or cold rolling mills can effectively roll hot rolled steel (e.g., hot bands or hot-rolled plates) to meet minimum lug height targets, particularly for the wide floor plates having widths greater than 84 inches. Therefore, the distribution of roll force, the main drive torque, and the allocation of thickness reduction between the top and bottom surfaces may be analyzed, as described below.

[0083] Under high rolling force, work roll flattening may be considered when calculating the projected arc length of the roll bite. FIG. 1 demonstrates the flattening deformation of work rolls within the roll bite. The original contour of the work roll (1) may be flattened to contour (2) in the roll bite. As depicted in FIG. 1, the roll radius within the roll bite may change from R to Ri due to flattening, and its center may shift from O to O1. The strip (3) may enter the roll bite at an initial gauge h0 and exit at a final gauge hi.

[0084] The projected arc length in the roll bite can be calculated using Hitchcock's expressions as follows:l1=R⁢Δ⁢h+x02+x0(1)x0=a⁢pm(2)a=8⁢R⁢1-v2π⁢E(3)Δ⁢u=2⁢l1⁢pm⁢1-v2π⁢E(4)where⁢ Δ⁢h=h0-h1⁢ (initial⁢ thickness⁢ h0⁢ minus⁢ final⁢ thickness⁢ h1),E=the⁢ Young’⁢s⁢ modulus⁢ of⁢ the⁢ work⁢ roll,v=the⁢ Poisson’⁢s⁢ ratio⁢ of⁢ the⁢ work⁢ roll,R=the⁢ work⁢ roll⁢ radius,pm=the⁢ average⁢ roll⁢ pressure⁢ over⁢ the⁢ projected⁢ ⁢arc⁢ length,Δ⁢u=the⁢ displacement⁢ of⁢ the⁢ roll⁢ contour.

[0085] A power-law relationship between true stress and true strain occurs for steels within the region of uniform plastic deformation, which extends from the yield strength to the tensile strength and hardness of Brinell. The mathematical relationships of the yield strength as, the tensile strength σb and Brinell hardness HB with respect to the relative reduction rate E may be expressed as:σs=σs⁢0+ks⁢εns(5)σb=σb⁢0+kb⁢εnb(6)HB=HB⁢0+kH⁢εnH(7)ε=Δ⁢hh0(8)where⁢ σs⁢0,σb⁢0⁢ and⁢ HB⁢0=the⁢ initial⁢ yield⁢ strength,tensile⁢ strength,and⁢ Brinell⁢ hardness⁢ without⁢ strain⁢ hardening,ks,kb⁢ and⁢ kH=constants⁢ for⁢ yield⁢ strength,tensile⁢ strength⁢ and⁢ Brinell⁢ hardness,ns,nb⁢ and⁢ nH=the⁢ strain-hardening⁢ exponents⁢ for⁢ yield⁢ strength,tensile⁢ strength⁢ and⁢ Brinell⁢ hardness.

[0086] These initial values, constants, and strain-hardening exponents may be determined through regression analysis of test results from multi-step cold reductions. The parameters may be categorized by chemical composition, rolling practice, and cooling scheme.

[0087] Rolling pressure models have been developed based on specific assumptions. Consequently, these models may be applicable under certain rolling conditions. For temper rolling operations, the gauge reduction rate may range from 0.5% to 6.0%. This slight reduction improves strip flatness and surface finish while avoiding strain hardening, which could reduce formability. For cold reversing rolling operations, the gauge reduction rate in the first pass targets 15% to 20% or more. For cold or warm-rolled floor plates, the gauge reduction rate ranges from between 2% and 20%, between 4% and 18%, between 6% and 16%, between 10% and 12%, between 4% and 10%, or the like.

[0088] It may be challenging to determine whether temper rolling or cold rolling models should be used. To simplify the model and consider the non-homogeneous deformation through thickness, a rolling pressure model without strip tension may be given as follows:pm=σc⁢m⁢eλ-1λ(9)l=R⁢Δ⁢h(10)λ=μ⁢l1hm(11)σc⁢m=1.1⁢55⁢ σs⁢m(12)hm=h0+h12(13)where⁢ σc⁢m,σsm=the⁢ average⁢ compressive⁢ and⁢ tensile⁢ yield⁢ strength⁢ between⁢ the⁢ entry⁢ and⁢ exit,μ=the⁢ friction⁢ coefficient⁢ in⁢ the⁢ roll⁢ bite.

[0089] In some implementations, the application of lubricants within the roll bite may reduce the separation force, roll torque, minimize roll wear, improve surface finish, or the like, by reducing friction of the roll bite. The use of lubrication may achieve higher lug heights while maintaining operation within the load and torque capacity limits of the mill. In some implementations, the application of lubricants may reduce the separating force and torque by approximately 5% to 10%, similar to the effect observed in cold rolling processes.

[0090] Commercial floor plates come in various patterns to provide slip resistance and aesthetic design for applications such as walkways, stair treads, and industrial flooring. FIGS. 2A and 2B illustrate two floor patterns recommended by ASTM A786 / A786M-15 (not to scale). Pattern No. 2 illustrated in FIG. 2A may be also known as the “tear-drop” pattern having lug 4 and base 5, while another common design may be the diamond pattern of FIG. 2B having lug 6 and base 7. Typically, these floor plates have a textured pattern on the top surface, with the bottom surface remaining flat and smooth. The ASTM A786 / A786M-15 specification regulates the minimum lug height, and the maximum lug height may be located at the center of the raised lug.

[0091] The diamond pattern, among other possible designs, may be used to illustrate the analysis of rolling parameters and pattern design. FIG. 3 depicts the geometric shape of a raised lug 8 and lug base 9 and the specific rolling force over one interval between two lugs. Assuming the specific load between the top of the lug and base of the lug in a parabolic distribution, the equilibrium force equation over the span from C to D may be as follows:qb⁢yb=qt(yb-2⁢yw3⁢cos⁢45⁢°-yr3⁢cos⁢45⁢°)⁢ or(14)qbqt=(1-2⁢2⁢yw3⁢yb-2⁢yr3⁢yb)=Ns(15)where⁢ qb,qt=the⁢ specific⁢ rolling⁢ forces⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,respectively,yw,yr=the⁢ top⁢ and⁢ bottom⁢ widths⁢ of⁢ the⁢ lug,yb=the⁢ transverse⁢ interval⁢ distance⁢ between⁢ lugs⁢ along⁢ the⁢ barrel⁢ length⁢ direction,Ns=a⁢ geometrical⁢ constant⁢ specific⁢ to⁢ the⁢ lug⁢ design,and⁢ Ns<1.

[0092] Equations (14) and (15) indicate that the specific rolling force on the top flat surface may be much higher than on the bottom surface, with the force ratio, Ns, for existing patterns ranging from 60% to 75% between the new machined roll and re-ground roll, given the same strip yield strength. This demonstrates that floor plate rolling may be an asynchronous rolling process with respect to the centerline of the thickness of the steel.

[0093] Total gauge reduction may be allocated between the top and bottom surfaces since lug height plays a role in slip and fall safety. These values may provide a basis for determining the notch depth of the work roll. FIG. 4 illustrates the geometric relationship in an asynchronous rolling process. In this process, the gauge reduction from the top work roll (e.g., first work roll) may be greater than that from the bottom work roll (e.g., second work roll) due to its higher specific rolling force (i.e., qb<qt). Thus, rolling a floor plate may be inherently an asynchronous process.

[0094] To simplify simulations, the asynchronous rolling can be modeled as a combination of two synchronous rolling processes due to heavy gauge, each acting independently on the top and bottom surfaces. The flat portion of the lug foot has more extension than the lug and the bottom surface, the flat portion suffers compression and the bottom surface, tension. By introducing tension factors ft and fb for the top and bottom surfaces, and using Equations (9) to (13), the rolling parameters for both surfaces can be expressed as follows:qb=pm⁢b⁢l1⁢b(22)qt=pmt⁢l1⁢t(17)pm⁢b=(1.1⁢5⁢5-fb)⁢σs⁢m⁢b⁢eλb-1λb(18)pmt=(1.1⁢5⁢5+ft)⁢σsmt⁢eλt-1λt(19)σs⁢m⁢b=1.1⁢5⁢5⁢(σs⁢0+12⁢ks⁢εbns)(20)σsmt=1.1⁢5⁢5⁢(σs⁢0+12⁢ks⁢εtns)(21)λb=μb⁢l1⁢bhm⁢b(22)λt=μt⁢l1⁢thm⁢t(23)l1⁢b=Rb⁢Δ⁢hb+(a⁢pm⁢b)2+a⁢pm⁢b(24)l1⁢t=Rt⁢Δ⁢ht+(a⁢pmt)2+a⁢pmt(25)hm⁢b=h0-12⁢Δ⁢hb(26)hmt=h0-12⁢Δ⁢ht(27)Δ⁢h=Δ⁢hb+Δ⁢ht2(28)where⁢ qb,qt=the⁢ specific⁢ rolling⁢ force⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,pmb,pmt=the⁢ unit⁢ rolling⁢ pressure⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,σsmb,σsmt=the⁢ average⁢ tensile⁢ yield⁢ strength⁢ of⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces⁢ between⁢ the⁢ entry⁢ and⁢ exit⁢ rolling⁢ pressure,fb,ft=the⁢ tension⁢ factors⁢ of⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,εb,εt=relative⁢ gauge⁢ reduction⁢ of⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,andεb=Δ⁢hb / h0,εt=Δ⁢ht / h0,l1⁢b,l1⁢t=the⁢ projected⁢ arc⁢ length⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,Rt,Rb=the⁢ top⁢ and⁢ bottom⁢ work⁢ roll⁢ radius,μb,μt=the⁢ friction⁢ coefficient⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces,Δ⁢hb / 2,Δ⁢ht / 2=the⁢ gauge⁢ reduction⁢ on⁢ the⁢ bottom⁢ and⁢ top⁢ flat⁢ surfaces.

[0095] Assuming the top and bottom work rolls have the same diameter and neglecting the difference of yield strength between the top and bottom surfaces, combining Equations (9), (15) to (17) yields:(1.1⁢5⁢5-fb)⁢σs⁢m⁢b⁢eλb-1λb⁢l1⁢b=Ns(1.1⁢5⁢5+ft)⁢σsmt(eλt-1λt⁢l1⁢t)(29)

[0096] Combining Equations (28) and (29), the solutions of Δhb and Δht can be obtained by using an iteration method. After determining Δhb and Δht, the specific rolling force on the bottom and top flat surfaces can be obtained, as shown in FIG. 7.

[0097] Another approach to determine Δhb and Δht may be to ignore the flattening of the work roll and stain-hardening difference between the top and the bottom surface. Substituting qb=(1.155−fb) σsm√{square root over (RΔhb)} and qt=(1.155+ft) σsm√{square root over (RΔht)} into Equation (15) produces:Δ⁢hbΔ⁢ht=[(1.1⁢5⁢5+ft)(1.1⁢5⁢5-fb)⁢Ns]2(30)

[0098] Since Equation (30) may not take into account the flattening of the work roll or the differences in hardening between the top and bottom surfaces, the ratio of Δhb to Δht may be lower. Consequently, the estimated lug height may be exaggerated, making this approach more applicable for softer materials.

[0099] For cold or warm rolled floor plates, the prediction of the separating force may play a role in determining the maximum lug height within the mill capability due to the high flow stress of the strip compared to hot rolling status. Since the distribution of the specific rolling force of the top work roll may be more complicated than that of the bottom work roll, the specific rolling force of the bottom work roll may be employed to calculate the total roll force as follows:P=qb⁢W(31)where⁢ W=strip⁢ width.

[0100] In an asynchronous rolling process, it may be beneficial to predict the torque of the top work roll since it may have more reduction than the bottom work roll. Also, the lugs on the top surface may restrict the strip slip forward. The forward slip rate of the top surface may be almost zero. The top and bottom work roll torques can be written as follows:Mt=Ψt⁢P⁢lt(32)Mb=Ψb⁢P⁢lb(33)where⁢ Mt,Mb=the⁢ torques⁢ of⁢ the⁢ top⁢ and⁢ bottom⁢ work⁢ rolls,respectively,Rt,Rb=the⁢ radii⁢ of⁢ the⁢ top⁢ and⁢ bottom⁢ work⁢ rolls,Ψt,Ψb=the⁢ roll⁢ force⁢ arm⁢ coefficients⁢ for⁢ the⁢ top⁢ and⁢ bottom⁢ work⁢ rolls.

[0101] In the rolling process, the forward slippage of the plate surface within the roll bite may increase with higher gauge reduction, greater roll surface friction, and a larger work roll radius, but decreases as the final plate thickness increases. On the top surface, when N3<1, the unraised portion may experience a greater reduction than the bottom surface, leading it to elongate more. However, the lugs in the notches of the work roll may help limit the forward slippage of this unraised portion.

[0102] Conversely, on the bottom surface, the neutral plane of the roll bite may shift toward the entry due to the drag exerted by the top surface, similar to the effect of added front tension. This shift may increase forward slippage on the bottom surface, which may redistribute the friction there.

[0103] Despite these variations in elongation, the bottom surface of the strip may move slightly faster than the work roll. This small speed differential may aid in keeping the strip relatively flat during rolling. The slightly quicker movement on the bottom surface may allow it to “catch up” with the top surface, balancing out the effects of differential friction and reduction across the strip's thickness. This balance may prevent “turn-up” or “turn-down” to assist in keeping the final product relatively flat and maintain the intended thickness profile.Surface Features of the Work Roll

[0104] A work roll may be provided with surface features to impart a lug pattern onto the floor plates. The ASTM A786 / A786M-15 specification establishes the minimum lug height but does not specify other dimensions such as lug length, intervals, or the widths of the lug's top surface and root. These particular dimensions may be defined by a manufacturer, a customer, or other entity, considering factors such as slip resistance, durability, appearance, and comfort.

[0105] According to full-scale pattern No. 4 in FIG. 2 of ASTM A786 / A786M-15, the geometric parameters of a lug may be measured as depicted in FIG. 5, with parameters defined in FIG. 3.

[0106] The axis of the grinding wheel (or cutter disc) 14 that forms the notches in the work roll may intersect the axis of the work roll 13 at a 45-degree angle, as illustrated in FIGS. 6a through 6c, which shows the geometric relationship between their axes. The notches within a work roll may be re-ground after a roll change (e.g., in order to continue to produce the specified lugs in the floor plate). In strip mills, notch depth may range from 1.524 mm (0.060 inch) to 1.905 mm (0.075 inch), between 0.75 mm and 1.2 mm, between 0.75 mm and 2.0 mm, between 1.2 mm and 2.0 mm, between 1.5 mm and 1.8 mm, between 1.6 mm and 1.7 mm, between 1.2 mm and 1.7 mm, between 1.0 mm and 1.7 mm, or the like. In other implementations, the notch depth may be within, overlap, or be outside of these ranges. The notch depth may be calculated using the following formula:g=R+r-R2-yl28-r2-yl24(34)where⁢ r=the⁢ radius⁢ of⁢ the⁢ grinding⁢ wheel,yl=the⁢ length⁢ of⁢ lug⁢ foot.

[0107] The width of the lug foot may be determined by:yr=yw,m⁢i⁢n +2⁢(g-Δ⁢g)⁢TAN⁡(β2)(35)where⁢ yw⁢ m⁢i⁢n=the⁢ edge⁢ height⁢ of⁢ the⁢ grinding⁢ wheel,Δ⁢g=the⁢ amount⁢ of⁢ re-ground;for⁢ the⁢ first⁢ time⁢ use,Δ⁢g=0,β=the⁢ taper⁢ angle⁢ of⁢ the⁢ grinding⁢ wheel.

[0108] The width of the top surface of the lug may be determined by:yw=yw⁢ m⁢i⁢n+2⁢(g-Δ⁢g-H)⁢TAN⁡(β2)(36)where⁢ H=the⁢ height⁢ of⁢ the⁢ lug,H=Δ⁢ht / 2.

[0109] In the experiment, and as illustrated in FIG. 21, it was found that a relationship exists between the ratio of the gauge reduction on the bottom surface to that on the top surface and the strip entry gauge when the total reduction is between 6.5% and 15%, and the lug height ranges from 0.019″ to 0.040″. This relationship may be expressed by the following regression equation:Δ⁢hbΔ⁢ht=c0+c1⁢h0(37)wherec0, c1=regression coefficients related to the steel's chemical composition and its hardenability.FIG. 21 illustrates that, as the entry gauge increases, a larger portion of the total gauge reduction occurs on the bottom surface compared to the top surface. In other words, for heavier gauges, a smaller fraction of the total gauge reduction may be transferred into lug heigh because the central region of the strip thickness accommodates a greater share of the compressive deformation. This finding may play a role in determining the tension factors of the bottom and top flat surface, fb and ft, respectively.Material and Mechanical Features of the Floor Plates

[0112] The mechanical properties of the floor plates produced as a result of the method disclosed herein may fall within the yield strength, tensile strength, and / or elongation percentage ranges of the standards illustrated in FIG. 11. However, other implementations may result in yield strength, tensile strength, and / or elongation percentage inside, outside, or overlapping the prescribed ranges of FIG. 11.

[0113] For example, the floor plate yield strength may range between 36 ksi and 80 ksi, 36 ksi and 85 ksi, 36 ksi and 65 ksi, 30 ksi and 70 ksi, 40 ksi and 60 ksi, 50 ksi and 70 ksi, 50 ksi and 85 ksi, 45 ksi and 75 ksi, 55 ksi and 65 ksi, 60 ksi and 80 ksi, 60 ksi and 85 ksi, 55 ksi and 85 ksi, 65 ksi and 75 ksi, or the like.

[0114] The tensile strength of the floor plates may range between 53 ksi and 95 ksi, 53 ksi and 60 ksi, 58 ksi and 95 ksi, 58 ksi and 80 ksi, 55 ksi and 85 ksi, 60 ksi and 75 ksi, 85 ksi, 80 ksi and 90 ksi, 75 ksi and 95 ksi, 70 ksi and 100 ksi, 80 ksi and 90 ksi, or the like.

[0115] The elongation percentage of the floor plates at a 2-inch gauge may range between 12% and 30%, 12% and 40%, 20% and 30%, 20% and 40%, 18% and 32%, 32% and 40%, 22% and 28%, 15% and 25%, 13% and 27%, 17% and 23%, 12% and 22%, 10% and 24%, 14% and 20%, or the like.

[0116] The lug heights of the floor plates produced as a result of the method disclosed herein may fall within the height ranges of the standards illustrated in FIG. 9 or other standard specifications. However, other implementations may result in lug heights inside, outside, or overlapping the prescribed ranges of FIG. 11. The lug height of the floor plate may be approximately 0.50 mm, approximately 0.60 mm, approximately 0.70 mm, approximately 0.80 mm, approximately 0.90 mm, approximately 1.00 mm, between 0.50 mm and 0.90 mm, between 0.60 mm and 0.80 mm, between 0.40 mm and 1.00 mm, between 0.2 mm and 0.5 mm, between 0.2 mm and 0.7 mm, or the like. The lug height may range between, overlap, or fall outside of any of the values and ranges described herein.

[0117] In some implementations, the lug heights may be substantially uniform across the floor plate. In other implementations, lug heights may vary across the length of the floor plate. Indeed, any pattern floor plate may benefit from the improvements in floor plate manufacturing disclosed herein.

[0118] The floor plate may conform to industry standards, including but not limited to, ASTM A1018 / A1018M-23a Structural Steel: Grades 36, 40, 45, 50, and 55, High-Strength Low-Alloy Steel under ASTM A1018 / A1018M-23a: Grades 45, 50, 55, and 60, ASTM A36 / A36M-19 Structural Steel, ASTM A572 / A572M-21e1 High-Strength Low-Alloy Steel: Grades 42, 50, 55, and 60, or the like, including any other equivalent structural steel or structural steels adhering to any domestic or international standards. Similarly, the lugs may meet the lug height and / or shape and / or layout specifications of ASTM A786 (or ASTM A786 / A786M-00b) Pattern No. 2, Pattern No. 4, Pattern No. 5, Pattern No. 6, or the like. In some implementations, the lugs may extend from one surface of the floor plate (e.g., the top surface or the bottom surface). In other implementations, the lugs may extend from opposing surfaces of the floor plate (e.g., the top surface and the bottom surface).

[0119] Moreover, the microstructure of hot-rolled steel or annealed steel of the floor plates may be based on pearlite-ferrite with a grain size coarser than No. 10 according to ASTM E112-13(2021). In addition, microalloy precipitates and alloy carbides may be present in the microstructure, contributing to strength and stability. The microstructure may largely resemble that of current hot-rolled floor plates. However, cold or temper rolling may increase the density of dislocations and modifies the aspect ratio of grains by elongating them, while the grain size number remains unchanged. This alteration may introduce anisotropy into the material without causing grain refinement or growth. These processing methods may improve mechanical properties such as strength and surface uniformity while preserving the microstructural characteristics.EXAMPLES

[0120] A Chromium Cast Iron work roll with a diameter of approximately 574.675 mm (22.625 inches) and hardness 85 to 90 ShC, was ground with diamond patterns, as illustrated in FIG. 8. The roll was pre-ground with a crown of 0.152 mm (0.006 inch) to compensate for the deflection of the roll stack due to high separating forces. While the Chromium Cast Iron work roll with a diameter of approximately 575 mm was chosen for the present example, other roller diameters are contemplated. For example, roll diameters between 300 mm and 900 mm, between 300 mm and 400 mm, between 300 mm and 500 mm, between 400 mm and 800 mm, between 400 mm and 500 mm, between 400 mm and 600 mm, between 500 mm and 600 mm, between 500 mm and 700 mm, between 550 mm and 600 mm, between 570 mm and 580 mm, between 575 mm and 590 mm, between 560 mm and 585 mm, between 565 mm and 595 mm, between 580 mm and 600 mm, between 580 and 800 mm, between 700 mm and 800 mm, between 800 mm and 900 mm, or the like are contemplated. While the work roll may be made out of Chromium Cast Iron (e.g., High Chromium Cast Iron of between 12 and 30% Cr), it should be understood that the work roll may be made out of other materials, such as but not limited to forged steel rolls, indefinite chilled double-poured (“ICDP”) cast iron rolls, high-speed tool steel rolls, or the like.

[0121] A total of fifty-seven notches were positioned around the circumference of the work roll at angles of 45° and −45°, with an interval distance of 31.674 mm (1.247 inches) relative to the roll axis. Along the barrel length, 83 notches were ground at a 45° angle, and 82 notches at a −45° angle with respect to the roll axis. The interval distance between adjacent lugs along the barrel length may be 31.75 mm (1.25 inches).

[0122] The geometric parameters of the lugs and the grinding wheel are shown in FIG. 9. A grinding wheel with a diameter of 106.680 mm (4.2 inches) and a taper angle of 118 degrees was selected. The ground notch depth may be 1.674 mm (0.066 inch) to 1.753 mm (0.069 inch) with notch length measuring around 25.781 mm (1.015 inches).

[0123] With a lug height set to 0.635 mm (0.025 inch), the predicted width of the lug's top surface may be 7.523 mm (0.296 inch), and the width of the lug root may be 9.637 mm (0.379 inch). If 0.762 mm (0.030 inch) may be re-ground after a roll change, the predicted widths adjust to 4.987 mm (0.196 inch) for the lug top surface and 7.101 mm (0.280 inch) for the lug root.

[0124] The chemical composition and mechanical properties of structural steels are shown in FIG. 10 and FIG. 11, respectively. ASTM A1018 SS36 and A36 mild carbon steels were selected for the trial; however, it should be understood that different types of steel compositions may be utilized having different types of compositions.

[0125] Two coils of each size, 9.525 mm (0.375 inch) and 12.700 mm (0.500 inch) by 2,438 mm (96 inches), were selected for temper-rolled floor plates. The temper mill line consists of an entry flattener, a 4-high temper mill, and a 5-over-6 leveler. All samples were collected after leveling. FIG. 12 illustrates the temper-rolled floor plate exiting the roll bite of the temper mill.

[0126] The sampling and testing plan is illustrated in FIG. 13. Four steps of roll forces were applied to the 12-foot front length of each coil. A transverse tensile sample 15 was collected for each step. Rolling parameters were collected from the Level 2 system. The lug height and gauge of the flat surface were measured using a depth meter and a micrometer.

[0127] According to ASTM A786 / A786M-15, tensile tests must be conducted on specimens with raised lugs, with thickness measured between these figures in unaffected areas. While percent elongation isn't required for rolled floor plates, it was included in the trials for the potential forming reference.

[0128] FIGS. 14A and 14B present the tensile properties of both sizes concerning gauge reduction rates. It shows that yield strength increases significantly with temper mill gauge reduction. The average yield strength gains for 9.525 mm and 12.700 mm (0.375 inch and 0.500 inch) gauges may be 115 MPa and 94 MPa (16.7 ksi and 13.6 ksi or 28.6% and 36.0% increase), respectively, and tensile strength gains may be 32 MPa and 16 MPa (4.7 ksi and 2.3 ksi, or 3.3% and 7.1% increase).

[0129] Indeed, average yield strength gains for 9.525 mm gauge may be approximately 115 MPa (16.7 ksi), between 114 MPa (16.5 ksi) and 115 Mpa (16.7 ksi), between 112 MPa (16.2 ksi) and 117 MPa (17.0 ksi), between 110 MPa (16.0 ksi) and 120 MPa (17.4 ksi), between 100 MPa (14.5 ksi) and 130 MPa (18.9 ksi), between 80 MPa (11.6 ksi) and 150 MPa (21.8 ksi), or the like, though the yield strength gains may be within, overlap, or be outside of these ranges.

[0130] Average yield strength gains for 12.700 mm gauge may be approximately 94 MPa (13.6 ksi), between 93 MPa (13.5 ksi) and 94 MPa (13.6 ksi), between 91 MPa (13.2 ksi) and 96 MPa (13.9 ksi), between 89 MPa (12.9 ksi) and 98 MPa (14.2 ksi), between 80 MPa (11.6 ksi) and 108 MPa (15.7 ksi), between 60 MPa (8.7 ksi) and 128 MPa (18.6 ksi), or the like, though the yield strength gains may be within, overlap, or be outside of these ranges.

[0131] Similarly, average tensile strength gains for 9.525 mm gauge may be approximately 32 MPa (4.6 ksi), between 31 MPa (4.5 ksi) and 32 MPa (4.6 ksi), between 30 MPa (4.4 ksi) and 34 MPa (4.9 ksi), between 28 MPa (4.1 ksi) and 36 MPa (5.2 ksi), between 20 MPa (2.9 ksi) and 44 MPa (6.4 ksi), between 10 MPa (1.5 ksi) and 54 MPa (7.8 ksi), or the like, though the tensile strength gains may be within, overlap, or be outside of these ranges.

[0132] Average tensile strength gains for 12.700 mm gauge may be approximately 16 MPa (2.3 ksi), between 15 MPa (2.2 ksi) and 16 MPa (2.3 ksi), between 14 MPa (2.0 ksi) and 18 MPa (2.6 ksi), between 12 MPa (1.7 ksi) and 20 MPa (2.9 ksi), between 10 MPa (1.5 ksi) and 22 MPa (3.2 ksi), between 5 MPa (0.7 ksi) and 26 MPa (3.8 ksi), or the like, though the tensile strength gains may be within, overlap, or be outside of these ranges.

[0133] In addition to the effect of lugs, strain hardening significantly contributes to this yield strength increase. Elongation percentage at a 2-inch gauge decreases by 10.3% and 6.9%, respectively, yet still meets ASTM A36's minimum elongation requirement (19%), despite floor plate elongation not being mandatory.

[0134] Higher yield strength improves the material's load-bearing capability, minimizing deformation under abrasive wear, as stronger materials tend to resist stress-induced deformation. In abrasive conditions, increased yield and tensile strength improve wear resistance while maintaining some ductility (or formability).

[0135] Hardness may be one measure for assessing wear resistance in the steel industry. In this study, Vickers hardness was measured with a 10 kg load, due to limitations on the top surface area of the lugs. FIGS. 15A-15D illustrate the relationship between Vickers hardness and both yield and tensile strengths for two sizes. As shown in the figure, hardness increases with higher yield and tensile strengths. Consequently, temper-rolled floor plates offer improved wear resistance compared to hot-rolled floor plates.

[0136] To assess formability, 90-degree transverse bending tests for both sizes were conducted (see FIG. 16). Two pin diameters, 38.1 mm and 50.8 mm (0.750 inch and 1.000 inch), were used to bend the 9.525 mm and 12.700 mm (0.375 inch and 0.500 inch) sizes, respectively-equivalent to a bending radius-to-thickness ratio of 2.0 (ASTM A36 allows a minimum of 2.25). No cracks were observed on the outer surface of the bent samples, as shown in FIG. 16.

[0137] Lug height plays a role in improving anti-slip performance and reducing trip hazards. FIG. 17A-17B illustrate the relationship between lug height and gauge reduction rate, providing guidance for ordering hot bands or plates with additional gauge for temper mill reduction, given that measuring the finished gauge at the temper mill may be challenging due to the presence of lugs. In addition to gauge reduction rate, FIGS. 18A-18B show that lug height may be correlated with the yield strength of the floor plates. Both FIGS. 17A-17B and FIGS. 18A-18B make it evident that as the gauge reduction rate and yield strength of the finished floor plates increase, so does the lug heightPost-Processing

[0138] Upon exiting the cold roll or tandem rolling operation, the floor plate, having the desired profile shape and lug pattern, may undergo one or more processing and handling steps, determined by the desired final properties and applications of the floor plate.

[0139] In some implementations, a coating may be applied to prevent corrosion from moisture, salts, and chemicals under the outdoor or high-wear environments, such as industrial plants and marine settings, etc. This may include galvanizing or electro-galvanizing, application of coatings such as aluminizing, organic paints, or polymer films, or the like.

[0140] In some implementations, scale removal prior to coating may be implemented. FIG. 19 compares the surface appearances after brushing, while FIG. 20 shows the surface of the final product. To assess the adhesion of scale on the steel surface, a steel brush wheel was used to remove the scale at a constant speed and contact pressure. As shown in FIG. 19, increasing the temper mill gauge reduction improves surface brightness since scale may be less ductile. The temper-rolled floor plate surface may be significantly easier to clean than the hot band surface. FIG. 20 highlights the uniform appearance of the finished floor plate.

[0141] In some implementations, floor plates destined for downstream industries may undergo custom cutting or slitting operations, where they are divided into narrower or shorter segments to meet specific customer flooring sizes or requirements.

[0142] Patterned work rolls in mills with a gauge reduction under stress-relieving temperatures (i.e., cold rolling or temper rolling) results in strain hardening (otherwise described as cold working or work hardening) that generates a permanent change to the crystalline structure of metal for floor plates. As a result, there is an improvement in the patterns for 4-way slip resistance, mechanical properties of the plates, hardness of lugs for abrasion resistance, and surface finish.

[0143] The improved floor plates, and the manufacturing thereof, may result in cost savings due at least in part to the reduction in the use of raw materials (e.g., scrap steel, direct reduced iron (DRI), iron ore, or the like) and / or alloying materials, and / or reduced manufacturing steps and / or manufacturing times for the production of the improved textured steel plate.

[0144] Aspects of the present disclosure result in less surface wear of the floor plates as compared to traditional plates. Under the stress-relieving temperatures and cold / warm reduction of the present disclosure, an increase in the surface hardness of the decarburization layer due to strain hardening may be achieved. In contrast, traditional plates and methods use hot-rolling reheating processes that result in a reduced-content decarburization layer on the floor plates that is between 0.2 mm and 0.5 mm thick, with less pearlite and microalloy formation as well as alloy carbides.

[0145] Aspects of the present disclosure result in improved mechanical properties of the floor plates when compared to traditional plates. The processing of the floor plate, as described herein, and in particular the strain hardening described herein, can improve plate strength by 10, 15, 20, 25, 30, 35, 40, 45, or the like percent, thus allowing for reduced floor plate thickness and / or lower microalloy additions while maintaining equivalent load capacity.

[0146] Aspects of the present disclosure result in improved surface finish of the floor plates when compared to traditional plates. Cold reduction in gauge of the floor plate while forming the lugs results in less scale on the surface and a more uniform appearance, which can be coated (e.g., painted, or the like) directly for improved corrosion resistance.

[0147] Aspects of the present disclosure result in improved manufacturing efficiency when compared to traditional plate manufacturing methods. A single cold rolling stand allows for improved scheduling for the production of small order quantities and timely delivery of orders. In contrast, traditional hot-rolled floor plates are produced by tandem strip mills that produce floor plates in high volumes only once or a few times per month, leading to cumbersome large inventories.

[0148] Aspects of the present disclosure result in improved manufacturing flexibility as compared to traditional plate manufacturing methods. The use of temper rolling may allow for the conversion of hot-rolled steel (e.g., hot bands or hot-rolled plates) into floor plates having widths that exceed 84 inches. In doing so, upgrading the tandem strip mills to produce such widths is avoided.

[0149] Furthermore, aspects of the present disclosure result in little-to-no impact to manufacturing output as compared to traditional plate manufacturing methods. The converting of hot rolled steel (e.g., hot bands or hot-rolled plates) to floor plates using a temper mill in a cut-to-length (CTL) line does not slow down output. In contrast, traditional processing methods, such as cold-stampeding methods of producing floor plates, result in floor plate production of predetermined length based on the stamp plates, which requires a slowing or stopping floor plate output during changeovers.

[0150] It should be understood that the steel composition in combination with the steel processing results in the properties of the steel. That is, using the same processing on steels having different compositions will result in different material properties. Additionally, using different processing (e.g., hot rolling passes, annealing types, annealing times and / or temperatures, cold rolling passes, pre-annealing, intermediate annealing, post annealing, or the like) on the same steel compositions will result in different steel properties. As such, the aspects of the present application, in particular, the steel processing alone or in combination with the composition of the steel results in the improved floor plates having the lugs, and the properties thereof.

[0151] While much of the foregoing has been described with reference to floor plates, it shall be understood that the present disclosure may have many other applications, including but not limited to wall and ceiling panels, vehicle and trailer surfaces such as truck beds and ramps, stair treads and landings, industrial equipment platforms and catwalks, decorative or architectural elements, dock and ship decking, protective covers and shields for cables or machinery, skid plates for automotive applications, shelving and storage, ramp construction, flooring mats, elevator floors, flooring or structural surfaces for bridges, tubes, pipes, or the like. Indeed, any application of traditional floor plates may benefit from the floor plates and method of manufacture disclosed herein. As such, it should be understood that the term floor plates described herein may be substituted with other types of products, whether or not specifically recited in this paragraph, and the patterned steel described herein and / or formed from the process described herein may be utilized for such application.

[0152] While certain exemplary implementations have been described herein, and shown in the accompanying drawings, it is to be understood that such implementations are merely illustrative of and not restrictive on the broad disclosure, and that this disclosure not be limited to the specific constructions and arrangements shown and described, since various other changes, combinations, omissions, modifications and substitutions, in addition to those set forth in the above paragraphs, are possible. Those skilled in the art will appreciate that various adaptations and modifications of the just described implementations can be configured without departing from the scope and spirit of the disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the disclosure may be practiced other than as specifically described herein.

Claims

1. A method of manufacturing a floor plate, the method comprising:cold rolling or temper rolling a hot rolled or annealed steel into the floor plate in one or more cold rolling passes or one or more temper rolling passes of a rolling apparatus, wherein the rolling apparatus comprises a first roller and a second roller and is structured to form a plurality of lugs in the floor plate while achieving a gauge reduction in the floor plate of between 2% and 20%.

2. The method of claim 1, wherein the cold rolling or the temper rolling is performed under stress-relieving temperatures of less than 675° C.

3. The method of claim 1, wherein the hot rolled steel comprises:0.035-0.25 weight % carbon;0.25-1.35 weight % manganese;with optional microalloy additions of one or more of vanadium (0.005-0.15 weight %), niobium (0.005-0.050 weight %), or titanium (0.005-0.040 weight %); anda remainder of iron and unavoidable impurities.

4. The method of claim 3, wherein the hot rolled or annealed steel further comprises:optional alloy additions of one or more of copper (0.20-0.40 weight %), nickel (0.20-0.50 weight %), or chrome (0.20-0.40 weight %).

5. The method of claim 1, wherein one of the first roller or the second roller comprises a pattern, the pattern structured to form a plurality of lugs on the floor plate comprising lug heights ranging from between 0.5 mm and 0.9 mm.

6. The method of claim 1, wherein the hot rolled steel has a thickness between 4.50 mm and 31.75 mm, regardless of a minimum width and a maximum width of the hot rolled steel, prior to the cold rolling or the temper rolling.

7. The method of claim 5, wherein a plurality of notches of the first roller or the second roller defines the pattern, and wherein at least one of the plurality of notches has a depth of between 0.75 mm and 2 mm.

8. The method of claim 1, wherein at least one of the first roller and the second roller has a diameter of between 400 mm and 800 mm.

9. The method of claim 1, further comprising:melting one or more charges of materials in an electric arc furnace into molten steel; andcasting the molten steel into the steel slab.

10. The method of claim 1, further comprising:hot rolling a steel slab in one or more hot rolling passes into a hot rolled steel; andannealing the steel between or after the one or more hot rolling passes into an annealed hot rolled steel.

11. A floor plate comprising:a base portion comprising a steel plate having a top surface and a bottom surface;a plurality of lugs extending from at least one surface of the steel plate, wherein the plurality of lugs are arranged to form a pattern, and wherein the plurality of lugs comprise lug heights ranging from between 0.5 mm and 0.9 mm.

12. The floor plate of claim 11, wherein the steel plate comprises:0.035-0.25 weight % carbon;0.25-1.35 weight % manganese;with optional microalloy additions of one or more of vanadium (0.005-0.15 weight %), niobium (0.005-0.050 weight %), or titanium (0.005-0.040 weight %); anda remainder of iron and unavoidable impurities.

13. The floor plate of claim 12, wherein the steel plate further comprises:optional alloy additions of one or more of copper (0.20-0.40 weight %), nickel (0.20-0.50 weight %), or chrome (0.20-0.40 weight %).

14. The floor plate of claim 12, wherein the plurality of lugs are formed from cold rolling or temper rolling a hot rolled or annealed steel into the floor plate in one or more cold rolling passes or one or more temper rolling passes of a rolling apparatus, wherein the rolling apparatus comprises a first roller and a second roller and is structured to form the plurality of lugs in the floor plate while achieving a gauge reduction in the floor plate of between 2% and 20%.

15. The floor plate of claim 14, wherein the cold rolling or temper rolling is performed under stress-relieving temperatures of less than 675° C.

16. The floor plate of claim 14, wherein the hot rolled or annealed steel has a thickness between 4.50 mm and 31.75 mm, regardless of a minimum width and a maximum width of the hot rolled steel, prior to being cold rolled or temper rolled.

17. The floor plate of claim 14, wherein a plurality of notches of the first roller or the second roller defines the pattern, and wherein at least one of the plurality of notches has a depth of between 0.75 mm and 2 mm.

18. The floor plate of claim 11, wherein the floor plate has a tensile strength of between 53 ksi and 95 ksi.

19. The floor plate of claim 11, wherein the floor plate has a yield strength between 36 ksi and 85 ksi.

20. The floor plate of claim 11, wherein the floor plate has an elongation percentage at a 2-inch gauge of between 12% and 40%.

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