Processing technology of a solid wire for gas shielded welding of high manganese austenitic cryogenic steel

Abstract

The invention discloses a processing technology for a solid wire used in gas shielded welding of high manganese austenitic cryogenic steel, which relates to the technical field of steel production. By formulating a multi-pass drawing and multiple annealing process, it solves the problems of severe work hardening caused by the high alloy composition of high manganese austenitic cryogenic steel, and the reduction of hot plasticity in a certain temperature range, resulting in easy wire breakage and difficult forming during the wire drawing process of the wire. It can produce solid wires for gas shielded welding of high manganese austenitic cryogenic steel with two specifications of φ1.6mm and φ1.2mm, making up for the deficiency of the wire drawing process after rolling in the processing of solid welding materials for gas shielded welding of high manganese austenitic cryogenic steel.

Description

Technical Field

[0001] The present invention relates to the technical field of steel production, and particularly relates to a processing technology for a solid wire used in gas shielded welding of high manganese austenitic cryogenic steel. Background Art

[0002] Liquefied natural gas (LNG) is usually stored in storage tanks at -162°C. At present, the steel used for LNG storage tanks is commercial 9Ni steel. Due to the high nickel content of up to 9%, the price of steel plates is expensive. In order to save Ni resources, reduce the cost of steel materials, and energy storage and transportation costs, researchers around the world are actively developing high manganese austenitic cryogenic steel.

[0003] In China, some universities and steel enterprises have taken the lead in jointly carrying out some theoretical and experimental research, and developed high manganese austenitic cryogenic steel suitable for LNG storage tanks. In the process of applying high manganese austenitic cryogenic steel to build storage tanks, welding is the key technology. Gas metal arc welding is a commonly used welding method, and a gas shielded welding solid wire matching with high manganese austenitic cryogenic steel is required to ensure the high quality of welded joints.

[0004] At present, there are two problems in the development of solid wires for gas shielded welding of high manganese austenitic cryogenic steel: First, wire drawing is the key process. There are existing technologies regarding wire rolling processes, but there is no wire drawing process after rolling. Second, due to the high alloy composition of high manganese austenitic cryogenic steel, its work hardening is serious, and there are problems such as a decrease in hot plasticity within a certain temperature range, which brings great difficulties to the research and formulation of wire drawing processes. Summary of the Invention

[0005] In view of the above technical problems, the present invention overcomes the shortcomings of the prior art and provides a processing technology for a solid wire used in gas shielded welding of high manganese austenitic cryogenic steel, including the following steps:

[0006] (1) Perform the first wire drawing on a raw material high manganese austenitic steel coil of a certain size;

[0007] (2) Put the coil after the first wire drawing into a pit furnace for the first annealing. The annealing temperature is 1050 - 1180°C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0008] (3) Perform the second wire drawing on the coil after the first annealing;

[0009] (4) Put the coil after the second wire drawing into an annealing furnace for the second annealing. The annealing temperature is 850 - 1170°C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0010] (5) The wire rod after the second annealing is subjected to a third drawing, and then polished 3 times to process it into a polished wire rod one.

[0011] (6) The polished wire rod one is put into a vacuum annealing furnace for the third annealing. The annealing temperature is 800 - 850 °C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100 °C before opening the furnace.

[0012] (7) The wire rod after the third annealing is subjected to a fourth drawing, and then subjected to 2 - 3 surface polishing treatments to process it into a polished wire rod two.

[0013] (8) The polished wire rod two is put into a vacuum annealing furnace for the fourth annealing. The annealing temperature is 800 - 850 °C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100 °C before opening the furnace.

[0014] (9) The wire rod after the fourth annealing is copper - plated to become a copper - plated wire.

[0015] (10) The copper - plated wire is wound in layers to obtain a finished product of a solid wire for gas - shielded welding with the required size.

[0016] The further limited technical solution of the present invention is:

[0017] The processing technology of the solid wire for gas - shielded welding of high - manganese austenitic low - temperature steel described above is used to produce solid wires for gas - shielded welding of high - manganese austenitic low - temperature steel with specifications of φ1.6mm and φ1.2mm.

[0018] The processing technology of the solid wire for gas - shielded welding of high - manganese austenitic low - temperature steel described above includes the following steps:

[0019] (1) The high - manganese austenitic steel wire rod with a diameter of φ7.0 - 7.5mm as raw material is drawn to φ6.0mm.

[0020] (2) The φ6.0mm wire rod is put into a pit furnace for the first annealing. The annealing temperature is 1050 - 1180 °C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100 °C before opening the furnace.

[0021] (3) The wire rod after the first annealing is drawn to φ4.5mm.

[0022] (4) The φ4.5mm wire rod is put into an annealing furnace for the second annealing. The annealing temperature is 850 - 1170 °C, the heat preservation time is 1 - 1.5 hours, and it is cooled in the furnace to 100 °C before opening the furnace.

[0023] (5) The wire rod after the second annealing is drawn to φ3.0mm, and then polished 3 times to process it into a φ2.8mm wire rod.

[0024] (6) Put the φ2.8mm wire rod into a vacuum annealing furnace for the third annealing. The annealing temperature is 800 - 850°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0025] (7) Draw the wire rod after the third annealing to φ1.8mm, and then perform 2 - 3 surface polishing treatments to process it into a φ1.5mm wire rod;

[0026] (8) Put the φ1.5mm wire rod into a vacuum annealing furnace for the fourth annealing. The annealing temperature is 800 - 850°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0027] (9) Copper - plate the wire rod after the fourth annealing to become a φ1.6mm copper - plated wire rod;

[0028] (10) Wind the copper - plated wire rod to obtain a finished product of a gas - shielded welding solid wire with a diameter of φ1.6mm.

[0029] The processing technology of the above - mentioned solid wire for gas - shielded welding of high - manganese austenitic low - temperature steel includes the following steps:

[0030] (1) Draw the high - manganese austenitic steel wire rod with a diameter of φ7.0 - 7.5mm as raw material to φ6.0mm;

[0031] (2) Put the φ6.0mm wire rod into a pit - type furnace for the first annealing. The annealing temperature is 1050 - 1180°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0032] (3) Draw the wire rod after the first annealing to φ4.5mm;

[0033] (4) Put the φ4.5mm wire rod into an annealing furnace for the second annealing. The annealing temperature is 850 - 1170°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0034] (5) Draw the wire rod after the second annealing to φ3.0mm, and then perform 3 polishings to process it into a φ2.8mm wire rod;

[0035] (6) Put the φ2.8mm wire rod into a vacuum annealing furnace for the third annealing. The annealing temperature is 800 - 850°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace;

[0036] (7) Draw the wire rod after the third annealing to φ1.8mm, and then perform 2 - 3 surface polishing treatments to process it into a φ1.1mm wire rod;

[0037] (8) Place the φ1.1mm wire rod into a vacuum annealing furnace for the fourth annealing. The annealing temperature is 800 - 850°C, the holding time is 1 - 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace.

[0038] (9) Copper-plate the wire rod after the fourth annealing to obtain a φ1.2mm copper-plated wire.

[0039] (10) Layer-wind the copper-plated wire to obtain a finished product of a gas shielded welding solid wire with a diameter of φ1.2mm.

[0040] For the processing technology of the above-mentioned solid wire for gas shielded welding of high manganese austenitic low-temperature steel, the chemical composition and mass percentage of the raw material high manganese austenitic steel wire rod are as follows: C: 0.30% - 0.55%, Mn: 24% - 26%, Ni: 6.4% - 8.2%, W: 2.5% - 4.0%, P ≤ 0.002%, S ≤ 0.001%, and the balance is Fe and inevitable impurities.

[0041] The beneficial effects of the present invention are as follows:

[0042] (1) The present invention can produce two specifications of solid wires for gas shielded welding of high manganese austenitic low-temperature steel, namely φ1.6mm and φ1.2mm, making up for the lack of the wire drawing process after rolling in the processing of solid welding materials for gas shielded welding of high manganese austenitic low-temperature steel, and meeting the current production requirements for solid wires for gas shielded welding that match high manganese austenitic low-temperature steel.

[0043] (2) By formulating a multi-pass wire drawing and multiple annealing process, the present invention solves the problems of severe work hardening caused by the high alloy composition of high manganese austenitic low-temperature steel, and the reduction of hot plasticity in a certain temperature range, resulting in easy wire breakage and difficult forming during the wire drawing process of the wire.

[0044] (3) The advantages of the processing technology design of the present invention are as follows:

[0045] The high-manganese austenitic low-temperature steel material has severe work hardening, so it is necessary to design multiple passes of drawing to avoid wire breakage during the drawing process due to excessive single-pass deformation; annealing treatment is carried out after each drawing to eliminate residual stress and improve its processing performance; the thermal conductivity of high-manganese steel is relatively low, about 1 / 3 of that of carbon steel. In order to make the core of the wire fully heated, the designed holding time is 1 to 1.5 hours; since the solidus temperature of this material is 1215 - 1290 °C, which is much lower than that of ordinary low-alloy steel, the heating and holding temperatures cannot be too high. Therefore, the highest heat treatment temperature designed in the present invention is 35 °C lower than the solidus; the high-manganese austenitic low-temperature steel has a problem of reduced hot plasticity in a certain temperature range and needs to be avoided. So the designed annealing temperatures are 1050 - 1180 °C, 850 - 1170 °C, and 800 - 850 °C; since the high-manganese austenitic low-temperature steel has poor oxidation resistance and is prone to generating oxide scale on the surface after annealing, the present invention designs two polishing treatment processes to ensure drawing accuracy and surface quality. Embodiment Example

[0046] The processing technology of a solid wire for gas shielded welding of high-manganese austenitic low-temperature steel provided in this example, the chemical composition and mass percentage of the raw material φ7.5mm high-manganese austenitic steel coil are as follows: C: 0.30% - 0.55%, Mn: 24% - 26%, Ni: 6.4% - 8.2%, W: 2.5% - 4.0%, P ≤ 0.002%, S ≤ 0.001%, and the balance is Fe and unavoidable impurities.

[0047] It includes the following steps:

[0048] (1) Draw the raw material φ7.5mm high-manganese austenitic steel coil to φ6.0mm;

[0049] (2) Put the φ6.0mm coil into a pit furnace for the first annealing, the annealing temperature is 1070 ± 10 °C, the holding time is 1.5 hours, and it is cooled in the furnace to 100 °C and then the furnace is opened;

[0050] (3) Draw the coil after the first annealing to φ4.5mm;

[0051] (4) Put the φ4.5mm coil into an annealing furnace for the second annealing, the annealing temperature is 1070 ± 10 °C, the holding time is 1.5 hours, and it is cooled in the furnace to 100 °C and then the furnace is opened;

[0052] (5) Draw the coil after the second annealing to φ3.0mm, and then carry out 3 times of polishing to process it into a φ2.8mm coil;

[0053] (6) Place the φ2.8mm wire rod into a vacuum annealing furnace for the third annealing. The annealing temperature is 840 ± 10°C, the holding time is 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace.

[0054] (7) Draw the wire rod after the third annealing to φ1.8mm, and then perform 2 surface polishing treatments to process it into a φ1.5mm wire rod.

[0055] (8) Place the φ1.5mm wire rod into a vacuum annealing furnace for the fourth annealing. The annealing temperature is 840 ± 10°C, the holding time is 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace.

[0056] (9) Copper-plate the wire rod after the fourth annealing to become a φ1.6mm copper-plated wire.

[0057] (10) Wind the copper-plated wire to obtain a finished product of a gas-shielded welding solid wire with a diameter of φ1.6mm, which is suitable for building a high-manganese austenitic low-temperature steel LNG storage tank. Example

[0058] The processing technology of a solid wire for gas-shielded welding of high-manganese austenitic low-temperature steel provided in this example includes the following steps as in Example 1:

[0059] (1) Draw the high-manganese austenitic steel wire rod with a diameter of φ7.5mm as the raw material to φ6.0mm.

[0060] (2) Place the φ6.0mm wire rod into a pit furnace for the first annealing. The annealing temperature is 1060 ± 10°C, the holding time is 1 hour, and it is cooled in the furnace to 100°C before opening the furnace.

[0061] (3) Draw the wire rod after the first annealing to φ4.5mm.

[0062] (4) Place the φ4.5mm wire rod into an annealing furnace for the second annealing. The annealing temperature is 860 ± 10°C, the holding time is 1 hour, and it is cooled in the furnace to 100°C before opening the furnace.

[0063] (5) Draw the wire rod after the second annealing to φ3.0mm, and then perform 3 polishings to process it into a φ2.8mm wire rod.

[0064] (6) Place the φ2.8mm wire rod into a vacuum annealing furnace for the third annealing. The annealing temperature is 810 ± 10°C, the holding time is 1.5 hours, and it is cooled in the furnace to 100°C before opening the furnace.

[0065] (7) Draw the wire rod after the third annealing to φ1.8mm, and then perform 3 surface polishing treatments to process it into a φ1.1mm wire rod.

[0066] (8) Put the φ1.1mm wire rod into a vacuum annealing furnace for the fourth annealing. The annealing temperature is 810 ± 10 °C, the holding time is 1 hour, and it is cooled in the furnace to 100 °C before opening the furnace;

[0067] (9) Copper plate the wire rod after the fourth annealing to become a φ1.2mm copper-plated wire rod;

[0068] (10) Layer wind the copper-plated wire rod to obtain a finished product of gas shielded welding solid wire with a diameter of φ1.2mm, which is suitable for building a high manganese austenitic low temperature steel LNG storage tank.

[0069] In addition to the above embodiments, the present invention may also have other implementation manners. All technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A processing technology for a solid wire used in gas shielded welding of high manganese austenitic low temperature steel, characterized in that: Used for producing solid cored wires for gas shielded welding of high manganese austenitic low temperature steel with specifications of φ1.6mm and φ1.2mm, including the following steps: (1) Drawing the high manganese austenitic steel wire rod with a diameter of φ7.0 - 7.5mm as raw material to φ6.0mm; (2) Placing the φ6.0mm wire rod into a pit furnace for the first annealing, with the annealing temperature of 1050 - 1180°C, the heat preservation time of 1 - 1.5 hours, and cooling in the furnace to 100°C before opening the furnace; (3) Drawing the wire rod after the first annealing to φ4.5mm; (4) Placing the φ4.5mm wire rod into an annealing furnace for the second annealing, with the annealing temperature of 850 - 1170°C, the heat preservation time of 1 - 1.5 hours, and cooling in the furnace to 100°C before opening the furnace; (5) Drawing the wire rod after the second annealing to φ3.0mm, and then performing 3 times of polishing to process it into a φ2.8mm wire rod; (6) Placing the φ2.8mm wire rod into a vacuum annealing furnace for the third annealing, with the annealing temperature of 800 - 850°C, the heat preservation time of 1 - 1.5 hours, and cooling in the furnace to 100°C before opening the furnace; (7) Drawing the wire rod after the third annealing to φ1.8mm, and then performing 2 - 3 times of surface polishing treatment to process it into a φ1.5mm or φ1.1mm wire rod; (8) Placing the φ1.5mm or φ1.1mm wire rod into a vacuum annealing furnace for the fourth annealing, with the annealing temperature of 800 - 850°C, the heat preservation time of 1 - 1.5 hours, and cooling in the furnace to 100°C before opening the furnace; (9) Copper plating the wire rod after the fourth annealing, the φ1.5mm wire rod becomes a φ1.6mm copper - plated wire coil, and the φ1.1mm wire rod becomes a φ1.2mm copper - plated wire coil; (10) Spooling the copper - plated wire coils, the φ1.6mm copper - plated wire coil gets the finished product of φ1.6mm solid cored wire for gas shielded welding, and the φ1.2mm copper - plated wire coil gets the finished product of φ1.2mm solid cored wire for gas shielded welding.

2. The processing technology of a solid wire for gas shielded welding of high manganese austenitic low temperature steel according to claim 1, characterized in that: The chemical composition and mass percentage of the raw material high manganese austenitic steel wire rod are as follows: C: 0.30% - 0.55%, Mn: 24% - 26%, Ni: 6.4% - 8.2%, W: 2.5% - 4.0%, P≤0.002%, S≤0.001%, and the balance is Fe and unavoidable impurities.