A high-reliability large-scale welded H-shaped steel production method

Abstract

The application discloses a high-reliability production method of large-scale welded H-shaped steel, which comprises the following steps: slab production: adopting 210-ton top and bottom combined blowing converter smelting and LF and RH vacuum refining, adopting low superheat casting, stable speed steel drawing and slab light pressing down technology, ensuring that the slab low multiple segregation is lower than C class 1.5 grade and no internal crack; the slab heating temperature is 1100-1180 DEG C, the heating time is 9-14 min / cm; the tapping temperature is 1090-1180 DEG C; T-shaped steel rolling: after the slab is discharged and descaled, the slab is rolled on a plurality of profile rolling mills in multiple passes, the rolling starting temperature is 1120 DEG C, and the final rolling temperature is 810-850 DEG C; H-shaped steel combined welding: the middle vertical plate of the straightened T-shaped steel is processed to be flush at the position 50 mm away from the root of the wing plate, and a V-shaped groove is formed; the strip steel plate cut from the plate with the same quality grade and thickness is used as the connecting plate in the middle of the H-shaped steel web, the clean groove and the nearby area are cleaned, and then the H-shaped steel is combined and butt-jointed in the horizontal position, after the combined welding and flaw detection and straightening, the size and shape of the H-shaped steel meet the relevant quality requirements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metallurgy, and particularly relates to a high-reliability production method of large-specification welded H-shaped steel. BACKGROUND

[0002] H-shaped steel is an important material in the construction industry and is usually used as a main component such as a load-bearing column or a frame beam. H-shaped steel currently includes rolled H-shaped steel and welded H-shaped steel. Rolled H-shaped steel is widely recognized as having high structural reliability because it is formed by rolling cast blanks and has no welds. However, due to the huge investment in production line equipment for rolled H-shaped steel, and the limitations of blank weight, rolling mill pass combination, and rolling mill capacity, some large, heavy, or special-specification H-shaped steels cannot be produced. Furthermore, due to the complex shape of H-shaped steel, it is difficult to achieve uniform cooling during rolling, so the strength grade of H-shaped steel that can be produced by rolling is greatly limited, and the yield strength grade is generally 345 MPa or below. Welded H-shaped steel has flexible size combinations and is not limited by blank weight and rolling equipment. It can be formed by welding plate strips of different sizes as webs and flanges to produce H-shaped steel as needed. The corner connection welds of the web and flange are the key load-bearing parts and are required to be the most stringent, with very high requirements for welding quality. At the same time, the welds are located at the corners, and the welding quality cannot be guaranteed. The welds and their surrounding areas are affected by welding heat cycles and welding material melting, and the corrosion resistance and fatigue life of the welded joint parts are lower than those of the base material area, which often leads to premature failure of the welded parts. Due to the above contradictions, welded H-shaped steel is considered to have much lower reliability than rolled H-shaped steel, and is generally only used in light and low-load steel structure workshops and buildings, greatly limiting its range of use.

[0003] Patent No. CN202110671604.9 "Hot-rolled H-shaped steel and production method thereof" can meet the production requirements of hot-rolled H-shaped steel with unequal thicknesses on both sides of the flanges, avoid side bending during rolling, control the difference between the metal flow rates of the flanges on both sides within a certain range during rolling, and thus stably produce hot-rolled H-shaped steel with unequal thicknesses on both sides of the flanges.

[0004] Patent No. CN202011243693.9 "A low-cost 460MPa excellent low-temperature toughness hot-rolled H-shaped steel and its production method" includes the following components by weight percentage: C: 0.03%~0.06%, Si: 0.20%~0.40%, Mn: 1.40%~1.60%, P≤0.01%, S≤0.005%, V: 0.07%~0.09%, Ni: 0.10%~0.25%, Cr: 0.10%~0.25%, N: 0.008%~0.010%, the rest is Fe and unavoidable impurities, the content ratio of V and N is 8:1-10:1; the content of Ni+Cr is 0.30%~0.40%, and the range of Ni:Cr is 1:1~1:2; the carbon equivalent CEV of the H-shaped steel is ≤0.38%, the welding crack sensitivity index Pcm is ≤0.18%, wherein the flange thickness of the H-shaped steel ranges from 30mm to 50mm, the yield strength of the H-shaped steel is 480MPa~540MPa; the tensile strength is 580MPa~680MPa, the elongation is 21%~28%, the low temperature impact toughness KV2 at-40℃ is ≥120J; the microstructure of the H-shaped steel flange is ferrite, pearlite and bainite, the grain size of the microstructure is 10~11, the ferrite grain size is 5μm~18μm, the volume of ferrite accounts for 70%~75% of the total volume, and the volume of bainite accounts for 10%~15% of the total volume.

[0005] Patent No. CN202010896072.4 A welding method for H-shaped steel submerged arc welding, how does the mechanical mechanism fix and position the web plate and implement welding during the welding process.

[0006] Patent No. CN202011242946.0 A thick heavy hot-rolled H-shaped steel for inhibiting grain growth and its production method, the thick heavy hot-rolled H-shaped steel includes the following components by weight percentage: C: 0.05%~0.20%; Si: 0.10%~0.50%, Mn: 0.80%~1.60%; Nb: 0.02%~0.04%; Ti: 0.008%~0.015%; N: 0.003%~0.005%, the balance is iron and other impurities; the flange thickness of the finished hot-rolled H-shaped steel prepared by using the thick heavy hot-rolled H-shaped steel ranges from 50mm to 150mm; wherein the preparation process of the finished hot-rolled H-shaped steel includes the following production steps: molten steel smelting, continuous casting of casting blank, heating furnace heating, cogging mill rough rolling, universal mill finishing, and cooling bed cooling, wherein the cooling speed of the continuous casting blank during the continuous casting process is controlled to be less than 5℃ / s, the volume fraction of TiN, NbC, Ti+Nb composite particles precipitated inside the casting blank after continuous casting is ensured to be 0.010%~0.060%, and the average diameter of the corresponding second phase particles is 10nm~45nm.

[0007] Patent CN202110361080.3, entitled "A Device for Solving the Problem of Inward Collision of the Lower Flange of H-beams During Hot Rolling," discloses a device for solving the problem of inward collision of the lower flange of H-beams during hot rolling. A wedge-shaped straightening structure is installed at the exit of the bridge after the roughing mill. On the projection of the wedge-shaped straightening structure onto the bridge base plate, the wedge-shaped straightening structure has its pointed end facing the H-beam entrance. The two sides of the wedge-shaped straightening structure form outwardly convex arc surfaces. The width of the wedge-shaped straightening structure reaches its maximum size at the H-beam exit. This technical solution reduces the amount of raw material removed by the flame cutting machine due to inward collision of the lower flange, reducing material waste and improving the yield rate. Simultaneously, the wedge-shaped straightening structure is connected to the bridge base plate by bolts, resulting in a simple structure that allows for quick replacement, improving work efficiency and reducing labor intensity. The structure can be adjusted as needed to meet the production requirements of different product specifications.

[0008] Existing patents are all about hot-rolled H-beam production methods, product development, and mechanical devices and straightening equipment for welding H-beams, but there are no highly reliable large-size welded H-beam production methods. Summary of the Invention

[0009] The purpose of this invention is to provide a highly reliable method for producing large-size welded H-beams.

[0010] The technical solution adopted by this invention to solve its technical problem is: a highly reliable method for producing large-size welded H-beams, comprising the following steps:

[0011] 1) Billet production: The billet meets the composition requirements of Q235D or Q345D, with the remainder being Fe and unavoidable impurity elements; it is smelted in a 210-ton top and bottom blowing converter and LF and RH vacuum refining. The refined molten steel has N≤0.0060% and S≤0.005%. Low superheat casting, steady speed steel pulling and billet light reduction technology are adopted to ensure that the low magnification segregation of the billet is lower than Class C 1.5 and there are no internal cracks; after the billet is placed on the ground, it is stacked and slow cooled for more than 48 hours.

[0012] 2) Billet heating: The billet heating temperature is 1100~1180℃, and the heating time is 9~14min / cm; the tapping temperature is 1090~1180℃;

[0013] 3) T-shaped steel rolling: after the casting blank is discharged and descaled, it is continuously rolled on a multi-pass profile mill, the rolling starting temperature is 1120 DEG C, the finish rolling temperature is 810-850 DEG C, the thickness of each part of the finished steel is between 10-40 mm, the cross-section compression ratio of the blank and the finished product is above 10, water cooling is used during rolling, and the finished product is uniformly cooled by using a water cooling device, the water cooling speed is controlled at 3-20 DEG C / s, the deformation of each part of the T-shaped steel is reduced, and the root of the convex wing plate of the vertical plate of the T-shaped steel after rolling is ensured to be not less than 60 mm, and the width of the wing plate of the T-shaped steel is not less than 150 mm;

[0014] 4) H-shaped steel combined welding: the vertical plate of the T-shaped steel after straightening is processed to be flush at a position 50 mm away from the root of the wing plate, and a V-shaped groove is opened; a strip steel plate cut from a plate of the same quality grade and thickness is used as a connecting plate in the middle of the web of the H-shaped steel, the connecting plate is combined and butt-jointed in a horizontal position after the groove and the surrounding area are cleaned, and the width of the web after combined welding meets the size requirements of the H-shaped steel; the welding method is submerged arc welding or gas shielded welding, and the welding material is a welding material matching the strength and quality grade of the base material;

[0015] 5) flaw detection and straightening: after welding and cooling, the weld of the H-shaped steel is detected, and the weld quality meets the requirements of ISO5817 B grade; then the H-shaped steel that passes the detection is straightened to ensure that the welded H-shaped steel meets the requirements of GB / T33814.

[0016] The present application has the following beneficial effects:

[0017] 1) The T-shaped steel and the plate are combined by welding to form the H-shaped steel, and the T-shaped steel and the plate have high quality;

[0018] 2) The T-shaped steel and the plate have simple shapes and are easy to produce by using temperature and cooling control processes, and have stable performance;

[0019] 3) The butt weld of the H-shaped steel is in a horizontal position, which is convenient for welding, and the weld quality is easy to guarantee; the weld is far away from the root of the intersection of the wing plate and the web, and the stress condition of the weld during use of the H-shaped steel is greatly improved, so the reliability and safety of the welded H-shaped steel of this form are greatly improved, and the use range of the welded H-shaped steel is greatly expanded. DETAILED DESCRIPTION

[0020] The present application will be further described in detail.

[0021] A high-strength and high-reliability large-size welded H-shaped steel production method, comprising the following steps:

[0022] 1) Casting blank production: The casting blank meets the composition requirements of GB / T 1591-2018 Q235D or Q345D, and the rest is Fe and inevitable impurity elements. A 210-ton top and bottom combined blown converter is used for smelting and LF, RH vacuum refining, and the refined molten steel N≤0.0060%, S≤0.005%. Low superheat casting, stable speed steel drawing and casting blank light pressing technology are used to ensure that the macrosegregation of the casting blank is below the C class 1.5 level, and there is no internal crack; the casting blank is stacked and slowly cooled after falling to the ground, and the slow cooling time is more than 48 hours.

[0023] 2) Casting blank heating: The casting blank heating temperature is 1100-1180℃, and the heating time is controlled according to 9-14min / cm; the tapping temperature is 1090-1180℃.

[0024] 3) "T" shaped steel rolling: After the casting blank is discharged and descaled, it is sent to a multi-pass profile mill with suitable pass to continue rolling. The rolling start temperature is 1120℃, the rolling end temperature is 810-850℃, the thickness of each part of the finished steel is between 10-40mm, the cross-section compression ratio of the blank and the finished product is more than 10, and water cooling can be used during rolling. After rolling, the water cooling device is used for cooling control, the water cooling speed is controlled at 3-20℃ / s, the deformation of each part of the "T" shaped steel is reduced, and the root of the convex wing plate of the vertical plate of the "T" shaped steel after rolling is not less than 60mm, and the width of the wing plate of the "T" shaped steel is not less than 150mm.

[0025] 4) H-shaped steel combined welding: The middle plate of the straightened "T" shaped steel is processed to be flush at a position about 50mm away from the root of the wing plate, and a V-shaped groove is opened; a strip-shaped steel plate cut from a medium plate with the same quality grade and thickness as the middle plate is used as a connecting plate in the middle of the H-shaped steel web. After cleaning the bevel and the surrounding area, the horizontal position is combined and connected, and the width of the web after combined welding meets the size requirements of H-shaped steel. The welding method is submerged arc welding or gas shielded welding, and the welding material is matched with the strength and quality grade of the base material.

[0026] 5) Flaw detection and straightening: After welding and cooling, the weld of the H-shaped steel is inspected, and the weld quality meets the requirements of ISO5817 B level; then the H-shaped steel that passes the flaw detection is straightened to ensure that the welded H-shaped steel size and shape meet the requirements of GB / T33814.

[0027] Example 1:

[0028] a) Casting billet production: using 210 tons top and bottom combined blowing converter smelting and LF, RH vacuum refining, the refined molten steel N≤0.0060%, S≤0.005%, using low superheat casting and stable speed steel, billet light pressing technology, to ensure that the casting billet low times segregation is lower than C class 1.5 level, no internal crack; after the casting billet landing, stacking and slow cooling, slow cooling time is more than 48 hours; billet size 2600mm, width 2200mm, thickness 300mm.

[0029] Table 1 smelting ingredients (%)

[0030] C Si Mn P S Als Ti N 0.14 0.35 1.45 0.018 0.004 0.030 0.015 0.004

[0031] b) Billet heating: the casting billet heating temperature is 1180℃, the heating holding time is 4.5 hours; the tapping temperature is 1150~1175℃;

[0032] c) "T" steel rolling: after the casting billet is descaled, it is sent to a multi-pass profile mill with suitable pass to continue rolling, the rolling starting temperature is 1090~1150℃, the finishing rolling temperature is 810~830℃, the cross-section compression ratio of the billet and the finished product is more than 10, water cooling can be used in the rolling process, the water cooling speed after rolling is controlled at 5~8℃ / s, and the deformation of each part is reduced. The height of the convex wing plate of the "T" steel after rolling is 75mm, the width of the wing plate of the "T" steel is 400mm, and the thickness of the vertical plate and the wing plate of the "T" steel is 16mm.

[0033] d) H-shaped steel combined welding: the vertical plate of the straightened "T" steel is processed to be flush at a position about 50mm away from the root of the wing plate, and a double-sided V-shaped groove is opened; a strip-shaped steel plate cut from a medium plate with the same quality grade and thickness is used as a connecting plate in the middle of the web of the H-shaped steel, and after cleaning the groove and the surrounding area, the horizontal position is combined and butt-jointed, and after combined welding, the web width meets the size requirements of the H-shaped steel.

[0034] Specific welding parameters: the welding groove is opened with a double-sided V-shaped groove, the V-shaped groove angle is 50~60℃, the gap is 1~3mm, the root face height is 2~3mm, and before welding, the rust, moisture and the like within 10mm range on both sides of the welding groove surface and the front and back surfaces are removed, and the metal gloss is exposed. The welding method uses CO2 shielded welding, direct current reverse connection, the gas pressure is not less than 1MPa, the welding wire H08Mn2SiA, the diameter is ψ1.2~ψ1.6mm, the welding wire extension length is 8~15mm, the welding voltage is 18~26V, the welding current is 170~210A, and the welding speed is 15~25m / h.

[0035] e) Flaw detection and straightening: after the welding cooling is completed, the weld is detected, and the weld quality meets the ISO5817 B level. The H-shaped steel that passes the detection is straightened to ensure that the size and shape of the H-shaped steel meet the requirements of GB / T33814.

[0036] Example 2:

[0037] a) Casting blank production: using a 210-ton top and bottom combined blowing converter to smelt and LF, RH vacuum refining, the refined molten steel N≤0.0045%, S≤0.003%, using low superheat casting and stable speed steel drawing to ensure that the macrosegregation of the casting blank is below the C class 1.5 level, and there is no internal crack; after the casting blank falls, it is stacked and slowly cooled for more than 48 hours; the blank is 2800mm long, 2195mm wide, and 300mm thick.

[0038] Table 2 Melting composition (%)

[0039] C Si Mn P S Als Nb Ti 0.12 0.38 1.35 0.015 0.003 0.036 0.025 0.017

[0040] b) Blank heating: the casting blank heating temperature is 1170℃, and the heating holding time is 4.6 hours; the tapping temperature is 1165℃.

[0041] c) "T" shaped steel rolling: after the casting blank is discharged and descaled, it is sent to a multi-pass profile mill with appropriate pass to continue rolling, the rolling start temperature is 1150℃, the rolling end temperature is 820~840℃, the cross-section compression ratio of the blank and the finished product is more than 10, water cooling can be used during rolling, the water cooling speed after rolling is controlled at 7~10℃ / s, and the deformation of each part is reduced. The protruding height of the center vertical plate of the "T" shaped steel after rolling is 80mm, the wing plate width of the "T" shaped steel is 450mm, and the thickness of the wing plate and the center vertical plate is 22mm.

[0042] d) H-shaped steel combined welding: the center vertical plate of the straightened "T" shaped steel is trimmed at a position about 55mm away from the root of the wing plate, and a V-shaped groove is opened; a strip-shaped steel plate cut from a medium plate with the same quality grade and thickness as the center vertical plate is used as the connecting plate in the middle of the H-shaped steel to ensure that the web width after combined welding meets the size requirements of the H-shaped steel. The groove is opened with a double-sided V-shaped groove, the V-shaped groove angle is 50~60℃, the gap is 2~3mm, the root face height is 3~4mm, and the rust, moisture and the like within a range of 10mm on both sides of the groove surface and the groove front and back before welding are removed, and the metal gloss is exposed. After welding 3 layers on one side, the other side is welded after turning over, and the welding root is polished before welding the other side. The welding adopts horizontal position submerged arc welding, direct current reverse connection, welding material ψ4.0mm welding wire H10Mn2 and welding agent J431, welding voltage 30~40V, welding current 380-500A, welding speed 40~50cm / min, and the distance between the welding electrode and the workpiece is 20~30mm.

[0043] e) Flaw detection and straightening: after the welding cooling is completed, the weld is subjected to flaw detection inspection, and the weld quality requirement meets ISO5817 B level. The H-shaped steel qualified after the flaw detection is straightened to ensure that the H-shaped steel appearance size meets the requirement of GB / T33814.

[0044] The present application is not limited to the above-mentioned embodiments, and any person should know that the structural changes made under the inspiration of the present application, any technical solution with the same or similar to the present application, falls within the protection scope of the present application.

[0045] The technology, shape, structure part not described in detail in the present application are all known technology.

Claims

1. A high-reliability production method of a large-scale welded H-shaped steel, characterized by, Comprising the following steps: 1) Casting blank production: the casting blank meets the component requirements of Q235D or Q345D, the rest is Fe and impurity elements; a 210-ton top and bottom combined blowing converter is used for smelting and LF, RH vacuum refining, the refined molten steel N≤0.0060%, S≤0.005%, low superheat casting, stable speed steel drawing and casting blank light pressing technology are used to ensure that the casting blank low multiple segregation is below C class 1.5 level, and there is no internal crack; after the casting blank falls, it is stacked and slowly cooled for more than 48 hours; 2) Casting blank heating: the casting blank heating temperature is 1100~1180℃, the heating time is 9~14min / cm; the tapping temperature is 1090~1180℃; 3) "T" shaped steel rolling: after the casting blank is discharged and descaled, it is continuously rolled on a multi-pass profile mill, the rolling starting temperature is 1120℃, the finishing rolling temperature is 810~850℃, the thickness of each part of the finished steel is between 10~40mm, the cross-section compression ratio of the blank and the finished product is more than 10, water cooling is used during rolling, uniform cooling is used after rolling, the water cooling speed is controlled at 3~20℃ / s, the deformation of each part of the "T" shaped steel is reduced, and the height of the root of the convex wing plate of the "T" shaped steel after rolling is not less than 60mm, the width of the wing plate of the "T" shaped steel is not less than 150mm; 4) H-shaped steel combined welding: the vertical plate of the straightened "T" shaped steel is processed to be flush at a position 50mm away from the root of the wing plate, and a V-shaped groove is opened; a strip steel plate cut from a medium plate with the same quality grade and thickness is used as a connecting plate in the middle of the H-shaped steel web, and the connecting plate is combined and butt-jointed in the horizontal position after cleaning the groove and the surrounding area; the welding method is submerged arc welding or gas shielded welding, and the welding material is matched with the strength and quality grade of the base material; 5) Flaw detection and straightening: after welding and cooling, the weld of the H-shaped steel is detected and inspected, and the weld quality meets the requirements of ISO5817 B level; then the H-shaped steel that passes the detection is straightened to ensure that the welded H-shaped steel meets the requirements of GB / T33814.