1100 mpa-grade ultra-high-strength wire rod and preparation method therefor

Abstract

Disclosed in the present invention is a 1100 MPa-grade ultra-high-strength wire rod, comprising the following components in percentage by weight: C: 0.065-0.18 wt%, Si: 1.13-1.82 wt%, Mn: 1.59-1.97 wt%, Cr: 0.41-0.98 wt%, Ni: 3.25-4.62 wt%, Mo: 0.41-0.98 wt%, Cu: less than or equal to 0.12 wt%, Ti: 0.04-0.10 wt%, P: less than or equal to 0.002 wt%, S: less than or equal to 0.015 wt%, V: less than or equal to 0.5 wt%, and the balance of Fe and inevitable impurities. Also disclosed is a preparation method for the wire rod. In the present invention, the strength can reach 1100 MPa while low-temperature toughness at -40°C is satisfied, a gas‑shielded solid welding wire of a corresponding strength grade is prepared and used for welding with Q1100E, and the cost is low.

Description

1100MPa grade ultra-high strength wire rod and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the field of steel materials, in particular to a 1100MPa grade ultra-high strength wire rod and a preparation method thereof. BACKGROUND

[0002] The demand for high-strength steel plates is increasing year by year because they are light in weight and high in strength, enabling the manufacture of large-scale and long-span equipment. In 2012, the state issued the GB / T 28909-2012 standard, which included Q1100E in the specification. However, when actually welding, there is no matching strength welding material, and only the existing highest strength 960MPa grade welding wire can be used for welding, so the manufacturing unit needs to avoid joint bearing in design, and the utilization rate of the steel plate performance is low, or the butt welding is abandoned and other connection methods are used, which greatly affects the application of the steel plate.

[0003] In the field of engineering machinery, due to the complex connection form of components, a convenient solid gas shielded welding wire is often used for welding. The core technology of this welding material lies in the development of wire rod composition, so in recent years, many researchers have been committed to developing high-strength smelting compositions. "CN115673597A" designs a high-strength composition with high strength and good ductility by targeting the deposited structure of ferrite, but its tensile strength is only 950MPa, which is difficult to match Q1100E for welding; "CN114799611B" discloses a composition with a strength of up to 1300MPa, but it contains 6% to 8% Ni, which is too high in manufacturing cost, and the cold crack sensitivity of welding is high, which is not conducive to mass production.

[0004] Therefore, it is necessary to develop a new type of ultra-high strength wire rod to meet the requirements of-40℃ low temperature toughness and strength of 1100MPa, and to reduce the cost.

[0005] SUMMARY

[0006] The present application provides a 1100MPa grade ultra-high strength wire rod and a preparation method thereof, which meets the requirements of-40℃ low temperature toughness and strength of 1100MPa, and prepares a solid gas shielded welding wire of the corresponding strength level, which is matched with Q1100E for welding, has low cost, and good processability.

[0007] Technical solution: The 1100MPa-grade ultra-high strength wire rod of the application is characterized in that the following components are included in the weight percentage: C is 0.065wt%-0.18wt%, Si is 1.13wt%-1.82wt%, Mn is 1.59wt%-1.97wt%, Cr is 0.41wt%-0.98wt%, Ni is 3.25wt%-4.62wt%, Mo is 0.41wt%-0.98wt%, Cu≤0.12wt%, Ti is 0.04wt%-0.10wt%, P≤0.002wt%, S≤0.015wt%, V≤0.5wt%, and the balance is Fe and inevitable impurities.

[0008] The preparation method of the 1100MPa-grade ultra-high strength wire rod of the application is characterized in that: the raw materials are smelted into molten steel, and then the square billets are made by the mode of die casting and forging rolling, the square billets are ground on the surface, heated in a heating furnace, and then sent to a wire rod rolling unit to be rolled into Φ6.5mm wire rods at a temperature of 910℃-930℃; after rolling, air cooling is performed, and the wire rods are placed in a hydrogen protection annealing furnace for cooling, and then taken out of the furnace for slow cooling to room temperature, so that the wire rods are prepared.

[0009] The wire rod is drawn by an uncoiling machine, and the surface oxide skin is removed, and then reduced in diameter from Φ6.5mm to Φ3.2mm by three drawing processes, and then annealed, and then reduced in diameter from Φ3.2mm to Φ1.4mm by three drawing processes again, and then secondary annealed, and finally fine-drawn to Φ1.2mm, and then plated with copper to prepare the solid gas shield welding wire.

[0010] The square billet has a side length of 150mm.

[0011] The square billet is ground on the surface to a depth of not less than 5mm, and chamfered.

[0012] The heating temperature in the heating furnace is 650℃, and the preheating time is 4h.

[0013] The cooling temperature in the annealing furnace is 550℃, and the cooling time is 4h.

[0014] The solid gas shield welding wire is protected by Ar+CO2 gas.

[0015] The solid gas shield welding wire is protected by 80% Ar+20% CO2 gas.

[0016] The tensile strength of the deposited metal obtained after welding of the solid gas shield welding wire reaches 1100MPa, and the impact toughness at-40℃ is good.

[0017] Beneficial effects: Compared with the prior art, the present application has the following remarkable advantages: the present application can prepare a solid gas shield welding wire of a corresponding strength level after simple drawing, meets the low temperature toughness of-40 DEG C, and the strength can reach 1100MPa, prepares a solid gas shield welding wire of a corresponding strength level, matches Q1100E for welding, has low cost, good process, and promotes the popularization and application of Q1100E. DETAILED DESCRIPTION

[0018] The technical solutions of the present application are further described below in combination with specific embodiments.

[0019] Embodiment 1:

[0020] The chemical components of the 1100MPa grade ultra-high strength wire rod of the present embodiment are as follows: C is 0.065wt%, Si is 1.53wt%, Mn is 1.97wt%, Cr is 0.98wt%, Ni is 4.15wt%, Mo is 0.98wt%, Cu≤0.12wt%, Ti is 0.04-0.10wt%, P≤0.002wt%, S≤0.015wt%, V≤0.5wt%, and the balance is Fe and inevitable impurities.

[0021] The above chemical components are used for molten steel smelting, and a 150mm square billet is prepared by mold casting and forging rolling. The square billet needs to be surface ground with a depth of not less than 5mm, and chamfered. After the surface grinding, the square billet is placed in a heating furnace at 650 DEG C for 4 hours, and then sent to a wire rod rolling mill at a temperature of 910-930 DEG C to be rolled into a Φ6.5mm wire rod. After rolling, air cooling is performed, and the wire rod is placed in a hydrogen protection annealing furnace at 550 DEG C for 4 hours, and then taken out and slowly cooled to room temperature, to obtain the wire rod.

[0022] The wire rod is drawn by an uncoiling machine to remove the surface oxide skin, and then reduced in diameter from Φ6.5mm to Φ3.2mm by three drawing processes, and then annealed, and then reduced in diameter from Φ3.2mm to Φ1.4mm by three drawing processes again, and then annealed again, and finally fine drawn to Φ1.2mm, and then plated with copper to prepare a solid gas shield welding wire.

[0023] The above gas shield welding wire is subjected to deposited metal detection.

[0024] With 80% Ar+20% CO2 protection, the strength of the obtained weld metal is 1177MPa, 1169MPa, and the low temperature impact at-40 DEG C is 48J, 48J, 52J, 46J, 39J.

[0025] Embodiment 2:

[0026] The chemical composition of the 1100 MPa grade ultra-high strength wire rod of this example is: C 0.12 wt%, Si 1.82 wt%, Mn 1.76 wt%, Cr 0.61 wt%, Ni 4.62 wt%, Mo 0.61 wt%, Cu≤0.12 wt%, Ti 0.04-0.10 wt%, P≤0.002 wt%, S≤0.015 wt%, V≤0.5 wt%, the balance being Fe and unavoidable impurities.

[0027] The above chemical composition is used to smelt the molten steel, and a 150 mm square billet is made by the mode of die casting and subsequent forging and rolling. The square billet needs to be surface ground to a depth of not less than 5 mm and chamfered. After surface grinding, the square billet is placed in a heating furnace at 650°C for 4 hours and then sent to a wire rod rolling mill to be rolled into a Φ6.5 mm wire rod at a temperature of 910-930°C. After rolling, air cooling is performed, and the wire rod is placed in a hydrogen-protected annealing furnace at 550°C for 4 hours, and then taken out of the furnace and slowly cooled to room temperature to obtain the wire rod.

[0028] The wire rod is drawn by an uncoiling machine to remove the surface oxide skin, and then reduced in diameter from Φ6.5 mm to Φ3.2 mm by three drawing processes, and then annealed, and then reduced in diameter from Φ3.2 mm to Φ1.4 mm by three drawing processes again, and then annealed again, and finally fine-drawn to Φ1.2 mm, and then plated with copper to obtain a solid flux-cored welding wire.

[0029] The above flux-cored welding wire is subjected to deposited metal detection.

[0030] The obtained weld metal has a strength of 1197 MPa and 1186 MPa, and a low-temperature impact at -40°C of 59 J, 62 J, 62 J, 76 J and 69 J under 80% Ar+20% CO2 protection.

[0031] Example 3:

[0032] The chemical composition of the 1100 MPa grade ultra-high strength wire rod of this example is: C 0.12 wt%, Si 1.82 wt%, Mn 1.76 wt%, Cr 0.61 wt%, Ni 4.62 wt%, Mo 0.61 wt%, Cu≤0.12 wt%, Ti 0.04-0.10 wt%, P≤0.002 wt%, S≤0.015 wt%, V≤0.5 wt%, the balance being Fe and unavoidable impurities.

[0033] The steel is smelted by using the above chemical components, and is made into 150mm square billets by die casting and subsequent forging and rolling. The square billets need to be surface ground with a depth of not less than 5mm, and are chamfered. After the surface grinding, the square billets are placed in a heating furnace at 650 DEG C for 4 hours, and are then sent to a wire rod rolling unit to be rolled into Φ6.5mm wire rods at a temperature of 910-930 DEG C. After the rolling, the wire rods are air cooled, and are then placed in a hydrogen-protected annealing furnace at 550 DEG C for 4 hours, and are then taken out of the furnace and slowly cooled to room temperature, so as to obtain the wire rods.

[0034] The wire rods are drawn by an unwinding machine to remove the surface oxide skin, and are then reduced in diameter from Φ6.5mm to Φ3.2mm by three drawing processes, and are then annealed, and are then reduced in diameter from Φ3.2mm to Φ1.4mm by three drawing processes again, and are then annealed again, and are finally drawn to Φ1.2mm, and are then plated with copper to obtain the solid flux-cored welding wire.

[0035] The above flux-cored welding wire is subjected to a deposited metal test.

[0036] The welding metal obtained by using 80% Ar+20% CO2 protection has a strength of 1221MPa and 1216MPa, and a low-temperature impact at-40 DEG C of 31J, 32J, 35J, 29J and 34J.

[0037] The present application reduces the addition of other alloys by reasonably designing the components of C, Mn, Cr, Ni and Mo to meet the requirement of strength of 1100MPa, and reduces the cost. The Zr alloy element is added in the present application to refine the grain of the welding seam and improve the strength, and the addition amount is low to be unable to achieve the effect, and the addition amount is too high to cause the cost to increase. In the present application, the square billets are placed in a heating furnace at 650 DEG C for 4 hours, and are then sent to a wire rod rolling unit, so as to ensure the temperature homogenization of the square billets, and to avoid the rolling defects caused by the large temperature difference of different positions in the subsequent heating and rolling process. In the present application, the wire rods are rolled into Φ6.5mm wire rods at a temperature of 910-930 DEG C, which is the best temperature range for the plasticity of the composition, and the wire rods are air cooled after the rolling, so as to effectively prevent the precipitation of carbides. In the present application, the wire rods after the rolling are placed in a hydrogen-protected annealing furnace at 550 DEG C for 4 hours, and are then taken out of the furnace and slowly cooled to room temperature, so as to control the shape of the surface oxide skin, and facilitate the removal of the oxide skin and the drawing process.

Claims

1. A 1100 MPa grade ultra-high strength wire rod, characterized by: The steel wire rod comprises the following components in the following weight percentage: C 0.065wt%-0.18wt%, Si 1.13wt%-1.82wt%, Mn 1.59wt%-1.97wt%, Cr 0.41wt%-0.98wt%, Ni 3.25wt%-4.62wt%, Mo 0.41wt%-0.98wt%, Cu≤0.12wt%, Ti 0.04wt%-0.10wt%, P≤0.002wt%, S≤0.015wt%, V≤0.5wt%, and the balance of Fe and inevitable impurities.

2. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 1, characterized by: The raw material is subjected to molten steel smelting, and then is forged and rolled to form a square billet, and the square billet is ground on the surface, heated in a heating furnace, and then sent to a wire rod rolling unit to be rolled into a Φ6.5mm wire rod at a temperature of 910-930℃; after rolling, the wire rod is air-cooled and placed in a hydrogen-protected annealing furnace to be cooled, and then is taken out of the furnace to be slowly cooled to room temperature, so as to obtain the wire rod.

3. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 2, characterized by: The wire rod is drawn by an unwinding machine to remove the surface oxide skin, and then is drawn in three passes to reduce the diameter from Φ6.5mm to Φ3.2mm, and then is annealed, drawn in three passes again to reduce the diameter from Φ3.2mm to Φ1.4mm, annealed again, and finally drawn to Φ1.2mm, and then plated with copper to form a solid flux-cored welding wire.

4. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 2, characterized by: The square billet has a side length of 150mm.

5. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 2, characterized by: The square billet is ground on the surface to a depth of not less than 5mm, and is chamfered.

6. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 2, characterized by: The heating temperature in the heating furnace is 650℃, and the preheating time is 4h.

7. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 2, characterized by: The cooling temperature in the annealing furnace is 550℃, and the cooling time is 4h.

8. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 3, characterized by: The solid flux-cored welding wire is protected by Ar+CO2 gas.

9. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 8, characterized by: The solid flux-cored welding wire is protected by 80% Ar+20% CO2 gas.

10. The process for producing 1100 MPa grade ultra-high strength wire rod according to claim 3, characterized by: The tensile strength of the deposited metal obtained after welding of the solid flux-cored welding wire reaches 1100MPa.