Cause Analysis of Continuous Pore and Iron Bean in Spiral Submerged Arc Welded Steel Pipe

After pickling, it was found that the position of the air hole iron bean is mostly located in the inner welding root. It is the inner part of the unit with a wider door. The 1 hole lacks the weld seam. The fracture morphology of the weld 12 is found by comparison. Even, no pores exist, and the bottom line of the weld pool at the root of the weld in the unit is relatively undulating, full of pores, 1 defect. After long-term observation, it is believed that the formation of the intermediary chain state is closely related to the formation of pores.

23 Forming joint state For thicker materials, we use internal welding planing. If there is no influence of the forming vertical roller extrusion thickness and other factors on the edge shape, the ideal forming joint state 3, however, due to the squeeze or roll of the pharyngeal roll Improper side roller pressure disc shear blade is not perpendicular to the edge of the steel strip shear welding roller roller or planing angle is not suitable, etc. The forming process is easily formed due to the influence of the 4 forming joint state foot large groove root formation Small bevels or similar to Xiao Yilian's evaluation of the weld seam will be followed. If the gap between the molding gaps is slightly larger or the position of the raw material changes when the head enters the pinch machine, the strip edge will be thickened or rolled. The edge roller is damaged, the gap on the cutting edge is not suitable, and the table 5 appears on the edge of the plate. These conditions will exacerbate this narrow gap phenomenon and the thicker the raw material, the more obvious this narrow gap phenomenon. The existence of this narrow gap phenomenon is extremely detrimental to welding, it is the continuous welding holes in the inner welding section. Tiedou 24 welding metallurgical analysis Let's take a look at the welding characteristics of this forming seam condition. The internal welding penetration of double-sided spiral submerged arc welding is made by two parts.

Part of it is formed by the mountain arc welding and blowing of the mother village, part of it is formed by the superheated molten pool gold, and the molten mother village is formed 6, and the welding molten pool is crystallized under motion. The welding arc cannot be directly blown due to the narrow gap of the inner welding root. The root of the groove is melted by the superheated molten pool metal. When the superheated molten pool metal melts the base material, when encountering the above-mentioned narrow gap of the root, due to lack of sufficient support, some liquid molten pool metal has a narrow root. gap. Furthermore, due to the strong magnetic properties of the forming bite seam, this narrow root gap often entrains the above-heated liquid solder pool gold with flux particles and flux iron oxide powder. It will be partially or completely melted into the liquid molten pool. The formation of inclusions and the occurrence of oxidization and reduction reaction with the dissolution pool, the reaction product 1 partly floated to the surface of the molten pool, and some remained in the molten pool. At a decrease of 6, near the crystallization temperature, the iron oxide and carbon in the molten pool metal undergo a violent redox reaction, resulting in a large amount of inclusions that do not float into the molten pool and become nucleated particles of carbon oxide pores. The nucleation of carbon oxide bubbles in the nucleus is inevitable. In the floating process, the position of 1 is deeper, lack of arc stirring, the viscosity of the Jichi continues to increase, and the floating of the bubbles is hindered by the dendrites of the inner welding root. , Part of the surface of the molten pool. There is also one part that stays in the inner weld and the root of the inner weld, forming 2 air holes and air hole cavities. , The gas nucleates on the inclusions, and the phenomenon of 2 inclusions in the pores appears, which is what we call iron. When this kind of defect passes through the outer welder, if the mining position is shallow, the outer welding will be burned and welded. It floats out of the outer welding pool; if the location is deep, or even a continuous pore is formed in the penetrating seam, this is the root cause of the porosity of the iron bean 1. The penetration depth formed by the arc directly blowing the base material 2 is overheated The melting depth of the molten pool metal is formed by melting the base metal 3.1. Starting from the state of forming the joint, eliminating or reducing the narrow gap at the root of the inner weld seam. First adjust the forming equipment such as forming stand, curling roller, disc shear, pad roller, etc. To make the edge of the strip steel flat, avoid squeezing or minimize squeezing, and avoid scratches and tables, which reach or approach the ideal forming joint state. Secondly, strengthen the inner welding or evening welding planing to reduce the narrow gap at the root of the inner welding. 3.2 Start from the steel belt docking position, align each pair of heads, try to eliminate the crescent, to reduce the change of the raw material position when the head enters the pinch machine In order to stabilize the joint quality of the forming seam, 3.3 adjust the welding parameters according to the shape of the edge of the forming seam. Appropriately increase the internal welding current to reduce the external welding current or appropriately reduce the internal welding current to increase the external welding current to reduce defects such as iron pores at the root of the weld. 3.4 From the perspective of molten pool metallurgy, use a flux with strong deoxidizing ability to enhance the deoxidation of the weld ability.

Jade 5 adjusts the position where the flux is fed so that it is as close as possible to the solder joint to reduce flux entrainment.

16Adjust the position of the inner welding point so that the inner welding point deviates from the bite point as much as possible to reduce the influence of the forming seam change, so that the weld point is in a stable seam state. Practice has proved that the above solutions are effective. Except for a few single stomata iron beans before and after the production, defects such as continuous stomata iron beans are completely eliminated, which also fully shows that the narrow gap phenomenon of the inner welding root is the small main root of the continuous stomata iron beans produced by the weld. , Zhang Wenyue. Welding metallurgy and metal weldability. Beijing, Machinery Industry Press, 1980, continued from page 40 and written in menus 03.15 and 03.16 respectively. Calculate the overload multiple cutoff value and overcurrent protection value of the motor according to the rated current of the motor, and write it to 04.05 respectively. If the quadrant is running, it should also be set. The same value of 4., 6 and 4., 5 and 03.12 and 03.13 for 05.06 Select the feedback method. If you select the code wheel feedback method, you should also write the mark factor of the juice to 03.14. Set the forward acceleration time and deceleration time to 02.04 and 2, 05. Then according to the use of the controller terminals, the signal flow between the controllers is logically related to the voltage and current configuration. At regular time, when the main circuit of the device is disconnected and the excitation of the motor is released, the magnetic field must be closed to enable 06.13 = 0 to close the magnetic detection 10. Block 1 password is open. 17 = 0, finished. When the left circuit is turned on, the current is automatically output to the rated and overcurrent, and it is automatically turned off after a few milliseconds before and after this time. The loaded current will measure the current interruption point parameter, 5.12, when the current is continuous, parameter, 5.131 parameter 05.14 , Motor constant 05.15, automatic storage, current loop parameter auto-tuning ends, set 06.13 = 1 into excitation setting. The core is fixed excitation 06.07 = 1000, so that 0608 = tuner rated excitation Tuning current; if it is weak magnetic system 06.07 = tuning machine rated Tuning weakening starting point, the minimum excitation current of 06.10 should be set. After passing the above series of menu parameters Of imitation. The system will operate according to the process requirements we set. 0142, the operation results of the spiral welded pipe machine also show that this all-digital DC speed controller has excellent performance, flexible configuration, convenient debugging, and faults. The characteristic of low rate is more and more favored by users and engineering technicians. With the improvement of performance and price ratio, it will be more widely applied in industry and other fields.

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