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This post was last edited by B0SS on 2018-8-30 at 18:13. k-TIG welding technology is a new type of high-current TIG welding technique that emerged around the year 2000, developed by CSIRO in Australia. The k-TIG welding process builds on traditional welding techniques by using a high current (>300A) to create a high arc pressure; this pressure achieves a relative balance with the surface tension of the molten metal in the weld pool, thereby forming a hole that enables deep penetration welding. During welding, the arc penetrates deep into the base metal, forcing the molten metal to the side walls of the weld pool and creating keyholes. If the arc pressure, the reactive force from the vapor generated by the evaporation of metal from the walls of the hole, and the surface tension of the liquid metal are in dynamic equilibrium with the internal pressure of the liquid metal, then the hole will remain stable. As the arc moves forward, the molten pool metal converges behind the arc and cools and solidifies to form a weld; the entire process is very similar to the plasma (pore) welding method. The welding process produces stable, fine ripples, resulting in an attractive weld shape; the microstructure and mechanical properties of the weld are superior to those obtained with TIG welding. There are many factors that affect the quality of K-TIG welding, including welding process parameters, tungsten electrode structure, gas shielding, and the external environment. 1. The geometric shape of the tungsten electrode; the maximum thermodynamic value density emitted by the cathode is related to the surface temperature of the tungsten electrode as well as its geometric parameters. The area from which thermions are emitted by the tungsten electrode is related to the welding current, the angle at the tip of the tungsten electrode, and the diameter of the tungsten electrode. Therefore, sinhttp://www.maihanji.com/bbs/%3CI%3Efile:%3C/I%3E///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wpsCEE6.tmp.png=Ad/Ac, where Ad is the cross-sectional area at the point where the largest diameter of thermions is produced, and Ac is the surface area over which thermions are emitted from the tungsten electrode; 2http://www.maihanji.com/bbs/%3CI%3Efile:%3C/I%3E///C:/Users/ADMINI~1/AppData/Local/Temp/ksohtml/wpsCEF6.tmp.png represents the angle at the tip of the tungsten electrode. 2. Types of shielding gas and gas flow rate. K-TIG welding typically uses pure argon as the shielding gas, and the gas flow rate during welding must be high enough to ensure that the shielding gas has sufficient integrity and improved resistance to interference. However, if the gas flow rate is too high, the turbulence of the shielding gas increases, drawing in external air into the welding area and reducing the effectiveness of shielding; this can result in pores forming in the weld during welding. Therefore, for k-TIG welding, a gas flow rate of 20 ml/min is generally sufficient to achieve good shielding effects. 3. A high-precision fixture and the proper coordination of welding process parameters (welding speed, welding current, arc voltage, etc.). During welding, the welding speed should be adjusted first, followed by the welding current. The welding speed is inversely proportional to the thickness of the plate. When the current exceeds 250A, arc pressure becomes a key factor in the formation and maintenance of a stable pore. In K-TIG welding, the behavior of these pores in the molten pool is a crucial factor affecting the shape of the weld seam and the quality of the welded joint. To achieve high-quality welded joints, it is necessary to study arc pressure and the factors that contribute to its formation. The following factors are related to the arc pressure in k-TIG welding: (1) Welding current: The welding current I is the main factor affecting the arc pressure F; (2) The tip angle of the tungsten electrode and the diameter of the tungsten electrode – a decrease in the tip angle or an increase in the electrode diameter results in an increase in arc pressure. For example, if the tip angle is reduced from 90 degrees to 30 degrees, the arc pressure will increase by 12%; if the tungsten electrode diameter is increased from 2.4 MM to 6 MM, the arc pressure will increase by around 9%. (3). Arc voltage: As the arc voltage increases, the heat generated by the arc increases as well, and the arc pressure rises. (4) Radius of the tungsten electrode boss: Reducing the radius of the boss will lower the arc voltage and increase the heat input. k-TIG welding apparatus. The K-TIG welding current is generally between 300A and 1000A, and it is mainly used for flat welding. Its system consists of the following components: (1) Welding control interface. (2) Welding power supply: DC input of 600–1000A; the welding current is proportional to the thickness of the metal plate being welded. A heat-start device is required to provide a surge current for starting the arc. This involves one 650A inverter, as well as another 1000A rectifier to supply higher currents. (3) Gas control system: Used for providing protection during welding, after welding (using a shield), and on the back side of the metal plate. (4). Circulating cooling system: Due to its high-power nature, a refrigeration water tank for air cooling is required. (5) Wire feeding system: Since the covering layer may not be very full, a wire feeder can be used to apply the cover layer. (6) Arc control system: The arc is a key factor in maintaining stability during welding. I. Functional features of the welding system for high penetration welders: 1. Automation of the welding process. 2. It is simple to operate; operators can perform tasks independently after two days of training. 3. Fast welding speed, 5-10 times faster than that of conventional TIG/GTAW. 4. At a certain thickness, welding the workpiece without the need for beveling allows for single-sided welding that results in a double-sided finished surface; the welds appear attractive, there is minimal deformation, and it is not necessary to clean the back side of the workpiece. 5. The width of the back weld seam is 2–3 millimeters, while the width of the front weld seam is usually around 1.5 times the thickness of the plate. 6. Single-sided welding with double-sided formation; convex welds can be achieved without the need for beveling or additional welding material, and surfacing can be carried out simultaneously if necessary. 7. It has a high welding tolerance; at a certain thickness, the gap and misalignment in the welded parts can reach 2 millimeters. 8. Welding covers materials such as carbon alloy steel, stainless steel, titanium alloys, nickel-based alloys, cobalt alloys, and zirconium, ensuring exceptional welding speed and quality. 9. The welding process is protected by argon gas. 10. High welding efficiency and low energy consumption. The equipment maintenance cost is low. Application areas 1: Petrochemical industry. 2. Food and pharmaceutical industries. 3. Water treatment industry. 4. Power plants (including the nuclear power industry). 5. Aerospace. 6. Shipbuilding. 7. Boilers and pressure vessels (mainly including: pipelines, heat exchangers, pressure vessels, storage tanks, cylindrical structures, reactors, etc.; welding of straight welds and circumferential welds during the manufacturing process of these pressure vessels and pipelines under normal and high pressures). 8. Prefabrication of pipes and assembly of panels in large-scale infrastructure construction