A welding method for argon arc welding of 10CR17 ferritic stainless steel

Abstract

This invention relates to the field of butt welding technology for pickled 400 series 10Cr17 ferritic stainless steel coils, specifically disclosing a welding method for argon arc welding of 10Cr17 ferritic stainless steel. The process involves: transporting the pickled 400 series 10Cr17 ferritic stainless steel coil to the uncoiler; conveying the 10Cr17 lead strip to the welding position via a suction cup from the lead strip storage stack to the lead strip platform; threading the pickled 400 series 10Cr17 ferritic stainless steel coil to the welding machine; pressing down with the uncoiler's pressure rollers; rotating the uncoiler; and guiding the lead strip of the pickled 400 series 10Cr17 ferritic stainless steel coil through a five-roll straightener, a head cutter, and a clamping roller to the welding machine's inlet clamp; welding machine operation; and after welding, cooling at room temperature. The weld seam is then cut with a crescent shear to remove any defective edges. This invention reduces the cost of the lead strip, minimizes changes in the microstructure of the surrounding base material, and effectively improves the success rate of argon arc welding of stainless steel.

Description

Technical Field

[0001] This invention relates to the field of butt welding technology for pickled white sheet 400 series 10Cr17 ferritic stainless steel, specifically to a welding method for argon arc welding of 10Cr17 ferritic stainless steel. Background Technology

[0002] 10Cr17 ferritic stainless steel is a general-purpose steel with good corrosion resistance, high mechanical properties, and high thermal conductivity. In addition to the good corrosion resistance of austenitic stainless steel, it has a significant price advantage and has gained widespread recognition for its high cost-performance ratio. Some domestic steel mills have shifted from cold rolling of austenitic stainless steel to cold rolling of 400 series stainless steel to expand the application market. In the production of 400 series stainless steel, 10Cr17 ferritic stainless steel, with its unique plate texture and material characteristics, increases the production difficulty of each process in cold rolling. In particular, the pickled white skin coil of 10Cr17 ferritic stainless steel is difficult to weld in the preparation unit, and the fracture rate after welding reaches more than 40%, which seriously affects the production rolling.

[0003] Currently, in the production of 10cr17 ferritic stainless steel pickled white steel coils in China, the main methods to control the breakage rate after welding are either welding austenitic stainless steel strips or not welding the strips, in order to reduce the impact on subsequent rolling processes. Some manufacturers also use laser welding machines for welding, but there has been no significant breakthrough in argon arc welding of 10cr17 ferritic stainless steel. For example, when producing 500 pieces, the breakage rate is >25%.

[0004] The specific composition of 10Cr17 ferritic stainless steel is as follows: C: 0.03-0.05%; Si: 0.20-0.50%; Mn: 0.30-0.50%; P: 0.035%; S: 0.006%; Ni: 0.30%; Cr: 16-16.5%; N: 0.020-0.050%; with the balance being Fe. Because 10Cr17 ferritic stainless steel has low toughness at room temperature, the weld joint will experience high-temperature embrittlement during welding, leading to high-temperature cracks under certain conditions. This is mainly because the thermal cycling of the weld joint causes rapid grain growth and coarsening in the near-weld zone, resulting in embrittlement in the temperature range of 400-540℃. To address this, companies typically reinforce the weld by patching the weld after welding to prevent breakage. While this method effectively improves welding quality, it is labor-intensive and reduces production efficiency. The main production method is to use 304 welding wire, welding current of 230A-270A, welding voltage of -5V-7V, and a fixed voltage and current control method. After welding, patch welding is performed longitudinally on the upper surface of the weld joint. The patch size is 3.0mm×70mm×150mm. Two patches are applied for a thickness of 3.0mm-4.0mm, and three patches are applied for a thickness greater than 4.0mm.

[0005] Technical analysis of the fracture phenomenon after welding of 10Cr17 ferritic stainless steel revealed intergranular fracture. The microstructure of the heat-affected zone of the samples was entirely Widmanstätten structure in extremely poor condition. The performance parameters of the weld and the matrix on both sides of the weld differed significantly. Specifically, tensile and bending tests were conducted on the samples. The samples showed no obvious yield strength, with a yield strength of 333-366 MPa and an elongation of 0.5-2%, far below the normal elongation of 22-30% for pickled 10Cr17 stainless steel. Bending tests showed that when the upper surface was on the weld side, a 100° bend did not crack; however, when the upper surface was on the opposite side of the weld, significant cracking occurred within a bend of no more than 10°. After grinding and polishing the sample weld section and etching it with ferric chloride solution, microhardness testing was performed. The hardness of the matrix and heat-affected zone on the cracked side was significantly lower. The hardness of the weld was 225-243 HV, the hardness of the matrix and heat-affected zone on one side was 160-187 HV, and the hardness of the matrix and heat-affected zone on the other side was 190-219 HV.

[0006] Therefore, it is necessary to design a welding method for argon arc welding of 10CR17 ferritic stainless steel to solve the problem of weld fracture in the existing stainless steel cold rolling process. Summary of the Invention

[0007] In view of the problems existing in the prior art, the purpose of this invention is to provide a welding method for argon arc welding of 10CR17 ferritic stainless steel, which reduces the investment cost of the lead strip, reduces the microstructure changes of the surrounding base material, and effectively improves the success rate of argon arc welding of stainless steel.

[0008] The technical solution adopted by this invention to solve its technical problem is: a welding method for argon arc welding of 10CR17 ferritic stainless steel, comprising the following steps:

[0009] S1. Pickled white sheet rolls are transported to the uncoiler: Control the thickness and width range of 10CR17 ferritic stainless steel welding, and transport the pickled white sheet rolls from the loading trolley to the uncoiler drum of the preparation unit.

[0010] S2, 10CR17 lead belt conveyed to the welding position: The uncoiler guide plate is raised, and the 10CR17 lead belt is lifted from the lead belt storage stack to the lead belt platform by the suction cup, and then conveyed to the outlet clamp of the argon arc welding machine by the idler roller conveying device and the clamping roller device of the lead belt platform.

[0011] S3. Pickled white leather roll is threaded to the welding machine: The uncoiler pressure roller is pressed down, the uncoiler is rotated, and the strip of the pickled white leather roll is threaded through the five-roll straightener, the head cutter, and the pinch roller to the inlet clamp of the welding machine.

[0012] S4. Welding machine operation: The welding machine is an argon arc welding machine, and the welding method is double gun welding. The welding machine is equipped with a front and rear centering device, a sleeve picking device, a crescent shear, and a weld annealing function.

[0013] The centering device of the welding machine is used to complete the centering of the strip and the pickled white strip. The buttons on the touch screen are used to complete the three tasks of pressing down the clamps at the outlet and inlet, cutting the strip, and splicing.

[0014] Input the lead strip thickness and pickled white sheet thickness via the touchscreen, input welding parameters, and adjust the power welding mode; after setting the parameters, complete the welding by pressing the motor welding button, and then sequentially complete the weld annealing.

[0015] S5. After welding, use room temperature cooling. After the measured temperature is below 400 degrees, use compressed air to cool down. After the plate surface temperature is below 80 degrees, pull the strip steel and let the weld enter the crescent shear to cut the crescent and cut off the unqualified parts on the edge.

[0016] Specifically, in step S1, the 10CR17 ferritic stainless steel has a thickness range of 2.75-5.5mm and a width range of 1000-1350mm. The pickled white sheet roll has a thickness of 3.0-5.0mm and a width of 900-1280mm. After the pickled white sheet roll is transported to the uncoiler drum, it is centered and the uncoiler drum is tightened.

[0017] Specifically, the 10CR17 lead tape in step S2 has a thickness of 3.0-5.5 mm, a width of 1000-1300 mm, and a length of 9-12 m.

[0018] Specifically, the welding machine used in step S4 is model NZ500C-1550T, and the welding wire used is model 309LSi. The chemical composition of the welding wire by mass percentage is as follows: C: ≤0.03%; Si: 0.65-1.0%; Mn: 1.0-2.50%; P: ≤0.030%; S: ≤0.015%; Ni: 12-14%; Cr: 23-25%; Mo: ≤0.050%; Cu: ≤0.75%.

[0019] Specifically, the input welding parameters in step S4 are as follows: front welding torch current 190-244A; rear welding torch current 190A-244A; front welding torch voltage 23.2-26.3V; rear welding torch voltage 23.2-26.3V; welding speed 562-630mm / min; annealing power 28-49KW; annealing speed 1.7-2.3m / min; and joint value 1.1-1.48mm.

[0020] Specifically, the adjustment of the power supply welding mode in step S4 is as follows: select the welding wire mode as 300 series stainless steel welding wire; select the power supply as dual pulse; adjust the parameters as follows: dual pulse frequency 1-3HZ, low pulse ratio 15-43%, low pulse current 35-60A, use argon gas with a purity of 98%, turn on the power supply heating function, adjust the pressure to 12-13mpa, and the gas output flow rate >18L / min.

[0021] Specifically, in step S4, the weld annealing process is judged by the visual appearance of the plate surface turning red, and dark red is not allowed.

[0022] The present invention has the following beneficial effects:

[0023] The argon arc welding method for 10CR17 ferritic stainless steel designed in this invention produces welds of high quality, less prone to cracking, with a fracture rate reduced to below 9%. Weld testing also demonstrates stability during the rolling process. Test results show: weld hardness of 320-360 HV, hardness of one side of the base material and one side of the heat-affected zone of 190-220 HV, and hardness of the other side of the base material and heat-affected zone of 180-220 HV. After rolling tests on a 20-roll mill under a starting tension of 20-27 tons, 13 passes were completed normally without any fractures.

[0024] After the weld formed by the argon arc welding method for 10CR17 ferritic stainless steel designed in this invention is stabilized, taking a 4.0mm thick, 1250mm wide, 20-ton pickled white steel coil as an example, 4 meters are cut off, and the yield is 99.1%. Compared with the previous method of cutting off 16 meters due to unstable weld, the yield is increased by 2.2%.

[0025] The argon arc welding method for 10CR17 ferritic stainless steel designed in this invention reduces the cost of lead wire, reduces the microstructure changes of the surrounding base material, and effectively improves the success rate of argon arc welding of stainless steel. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be described clearly, completely, and in further detail below. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] To address the weld fracture problem during the cold rolling process of stainless steel and reduce the input cost of the lead strip, a welding process for argon arc welding of 10CR17 ferritic stainless steel was invented. This process reduces the microstructure changes of the surrounding base material and effectively improves the success rate of argon arc welding of stainless steel. The welding wire used is 309LSi, with the following chemical composition: C: ≤0.03%; Si: 0.65-1.0%; Mn: 1.0-2.50%; P: ≤0.030%; S: ≤0.015%; Ni: 12-14%; Cr: 23-25%; Mo: ≤0.050%; Cu: ≤0.75%.

[0029] To achieve the above objectives, the technical solution adopted in this invention is: a welding process for argon arc welding of 10CR17 ferritic stainless steel, which is completed by the following steps:

[0030] 1. Pickled white stainless steel rolls are transported to the uncoiler: The pickled white stainless steel rolls are made of 10CR17 ferritic stainless steel with a thickness range of 2.75-5.5mm and a width range of 1000-1350mm. A pickled white stainless steel roll with a thickness of 3.0-5.0mm and a width of 900-1280mm is transported from the upper winding trolley to the uncoiler drum of the preparation unit, and the centering position is completed. The drum is then tightened.

[0031] 2. 10CR17 guide belt conveyed to the welding position: The uncoiling machine guide plate is raised, and a 10CR17 guide belt with a thickness of 3.0-5.5mm, a width of 1000-1300mm, and a length of 9-12m is lifted from the guide belt storage stack to the guide belt platform by a suction cup. The guide belt platform is then conveyed to the outlet clamp of the argon arc welding machine by the idler roller conveying device and the clamping roller device.

[0032] 3. Passing the pickled white leather roll to the welding machine: The uncoiler pressure roller presses down, and the uncoiler rotates to pass the end of the pickled white leather roll through the five-roll straightener, the head cutter, and the pinch roller to the inlet clamp of the welding machine.

[0033] 4. Welding machine operation: The welding machine is an argon arc welding machine, model NZ500C-1550T. The welding method is double gun welding. The welding machine is equipped with front and rear centering devices, sleeve picking devices, crescent shears and weld annealing function.

[0034] The centering device of the welding machine is used to complete the centering of the strip and the pickled white strip. The buttons on the touch screen are used to complete the three tasks of pressing down the clamps at the outlet and inlet, cutting the strip, and splicing.

[0035] Input the lead-in strip thickness and pickled white sheet thickness via the touchscreen. Input the welding parameters as follows: front and rear gun current, front and rear gun voltage, front and rear gun welding speed, annealing power, annealing speed parameters, and joint gap. See Table 1 for detailed data.

[0036] Table 1: Welding Parameter Table

[0037]

[0038] Adjust the power supply welding mode: Select welding wire mode: 300 series stainless steel welding wire; power supply selection: dual pulse; adjust parameters as follows: dual pulse frequency 1-3HZ, low pulse ratio 15-43%, low pulse current 35-60A. See Table 2 for detailed data.

[0039] Table 2: Power Supply Adjustment Parameter Table

[0040] 3.0 1 43 35 3.5 1 36 37 4.0 2 29 44 4.5 2 20 52 5.0 3 15 60

[0041] Use 98% pure argon gas, turn on the power and heat the device, adjust the pressure to 12-13 MPa, and the gas output flow rate is >18 L / min.

[0042] After setting the parameters, welding is completed by pressing the welding button on the motor, and the weld annealing is completed sequentially. During the weld annealing process, the red color of the board surface is used as the criterion for judgment, and dark red phenomena are not allowed.

[0043] After welding, the strip is cooled to room temperature. Once the temperature is below 400 degrees Celsius, compressed air is used for cooling. When the plate surface temperature is below 80 degrees Celsius, the strip is pulled and the weld is cut into the crescent shear to remove any unqualified parts at the edges.

[0044] Example 2: 10CR17 ferritic stainless steel pickled white sheet roll with a thickness of 3.5mm, a strip thickness of 3.5mm, and a width of 1250mm.

[0045] 1. After selecting a strip with a thickness of 3.5mm and a width of 1250mm, the strip is lifted from the storage stack to the strip conveying platform of the preparation unit by a suction cup crane. The strip is then conveyed to the welding machine outlet clamping plate through the conveying rollers and the strip clamping rollers.

[0046] 2. The 3.5mm thick pickled white leather roll is transported from the upper winding trolley to the uncoiling machine mandrel. After measurement and alignment are completed, the uncoiling machine rotates forward to transport the lead of the pickled white leather roll to the welding machine inlet clamp.

[0047] 3. Lead Welding Operation: The centering device of the welding machine is used to center the lead strip and the pickled white strip. The touchscreen is used to operate the buttons to perform three tasks: pressing down the clamps at the inlet and outlet, shearing the strip, and splicing. The lead strip thickness and pickled white strip thickness are input via the touchscreen. The welding parameters are: front and rear gun current, front and rear gun voltage, front and rear gun welding speed, annealing power, annealing speed parameters, and splice gap. Detailed data is shown in Table 3.

[0048] Table 3: Welding Parameter Table

[0049]

[0050] Adjust the power supply welding mode: Select welding wire mode: 300 series stainless steel welding wire; power supply selection: dual pulse; adjust the dual pulse frequency, low pulse ratio, and low pulse current. See Table 4 for detailed data.

[0051] Table 4: Power Supply Adjustment Parameter Table

[0052] 3.5 1 36 37

[0053] After confirming the parameters, click "Cut and Join". The welding machine will cut and join the seam. Position the welding torch and click "Start Welding" to complete the welding of the front and rear welding torches. After welding, perform weld annealing. After weld annealing, use the button to transport the strip to the cooling position and allow the weld to cool naturally for 1 minute. Then, turn on compressed air to purge and cool down the temperature to 60 degrees Celsius before using crescent shears for cutting.

[0054] 4. Using the control panel buttons, feed the head guide belt into the coiler, press down the three-roll tension device of the preparation unit, establish the uncoiling and coiling tension of the preparation unit, and complete the production operation of the steel coil. After the steel coil is uncoiled, the tail end detaches from the coiler, falls down through the straightening rollers of the uncoiler to flatten the tail end, and is then conveyed to the rear pressure plate of the welding machine.

[0055] 5. The strip steel is loaded onto the coiler via the control panel. The unloading trolley then transports the coil from the coiler to the saddle, completing the coil bundling process and finishing the coil production.

[0056] This invention is not limited to the above-described embodiments. Anyone should know that any structural changes made under the guidance of this invention, and any technical solutions that are the same as or similar to this invention, fall within the protection scope of this invention.

[0057] The technologies, shapes, and structures not described in detail in this invention are all known technologies.

[0058] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A welding method for argon arc welding of 10CR17 ferritic stainless steel, characterized in that, Includes the following steps: S1. Pickled white sheet rolls are transported to the uncoiler: Control the thickness and width range of 10CR17 ferritic stainless steel welding, and transport the pickled white sheet rolls from the loading trolley to the uncoiler drum of the preparation unit. S2, 10CR17 lead belt conveyed to the welding position: The uncoiler guide plate is raised, and the 10CR17 lead belt is hoisted from the lead belt storage stack to the lead belt platform by the suction cup, and then conveyed to the outlet clamp of the argon arc welding machine by the idler roller conveying device and the clamping roller device of the lead belt platform. S3. Pickled white leather roll is threaded to the welding machine: The uncoiler pressure roller is pressed down, the uncoiler is rotated, and the strip of the pickled white leather roll is threaded through the five-roll straightener, the head cutter, and the pinch roller to the inlet clamp of the welding machine. S4. Welding Machine Operation: The welding machine is an argon arc welding machine, using a double-gun welding method. It is equipped with front and rear alignment devices, a sleeve-picking device, crescent shears, and weld annealing function. The welding machine model is NZ500C-1550T, and the welding wire type is 309LSi. The chemical composition (mass percentage) of the welding wire is: C: ≤0.03%; Si: 0.65-1.0%; Mn: 1.0-2.50%; P: ≤0.030%; S: ≤0.015%; Ni: 12-14%; Cr: 23-25%; Mo: ≤0.050%; Cu: ≤0.75%. The centering device of the welding machine is used to complete the centering of the strip and the pickled white strip. The buttons on the touch screen are used to complete the three tasks of pressing down the clamps at the outlet and inlet, shearing the strip, and splicing. Input the thickness of the lead strip and the thickness of the pickled white sheet through the touch screen. Input the welding parameters as follows: front welding torch current 190-244A; rear welding torch current 190A-244A; front welding torch voltage 23.2-26.3V; rear welding torch voltage 23.2-26.3V; welding speed 562-630mm / min; annealing power 28-49KW; annealing speed 1.7-2.3m / min; joint gap 1.1-1.48mm; adjust the power supply welding mode as follows: select 300 series stainless steel welding wire mode; select dual pulse power supply; adjust the parameters as follows: dual pulse frequency 1-3HZ, low pulse ratio 15-43%, low pulse current 35-60A, use 98% pure argon gas, turn on the power heating function, adjust the pressure to 12-13MPa, and the gas output flow rate >18L / min; after setting the parameters, complete the welding by pressing the motor welding button, and then complete the weld annealing sequentially. S5. After welding, use room temperature cooling. After the measured temperature is below 400 degrees, use compressed air to cool down. After the plate surface temperature is below 80 degrees, pull the strip steel and let the weld enter the crescent shear to cut the crescent and cut off the unqualified parts on the edge.

2. The welding method for argon arc welding of 10CR17 ferritic stainless steel according to claim 1, characterized in that, In step S1, the thickness of the 10CR17 ferritic stainless steel ranges from 2.75 to 5.5 mm and the width ranges from 1000 to 1350 mm. The thickness of the pickled white sheet roll is 3.0 to 5.0 mm and the width is 900 to 1280 mm. After the pickled white sheet roll is transported to the uncoiler drum, it is centered and the uncoiler drum is tightened.

3. The welding method for argon arc welding of 10CR17 ferritic stainless steel according to claim 1, characterized in that, The thickness of the 10CR17 lead tape in step S2 is 3.0-5.5 mm, the width is 1000-1300 mm, and the length is 9-12 m.

4. The welding method for argon arc welding of 10CR17 ferritic stainless steel according to claim 1, characterized in that, In step S4, the weld annealing process is judged by the red color of the plate surface as observed by the naked eye, and dark red phenomena are not allowed.

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