The Manufacture Of Multiple Concentric Cored Underwater Electrode

At present, the underwater wet welding arc is used widly for it’s economical and pracrical in underwater welding. The most common defects in wet underwater welding are hydrogen-induced cracking and poor weld, but due to the reason of environment and equipment, the submerged arc which is with good formability can not be applied to underwater welding. Existing underwater electrode protection requirement is strict for drug skin and needs to be removed waterproof layer before used. In view of the above problems, multi-strand concentric underwater cored electrode is developed based on the principle of SAW, after the room-temperature onshore and underwater flat welding test, discussing the performance characteristics of this new type of electrode and determine the scope of the optimum flux ratio after the comparation of the ordinary electrode THJ422,TS202 and self-made results in welded joints metallographic observation and hardness measurement.The following main conclusions are reached:1. Self-made welding arc continuty is slightly lower than TS202 in the underwater wet welding,but with the increase of the number of flux cored wires that the stability of arc has gradually improved. In the same parameters, the decrease of flux ratio will lead to increase weld coefficient, the difference between self-made welding and TS202 is 0.02 to 0.36. The optimum flux ratio is in the range of 70% to 77% according to the results of test.2. Compared with the TS202, the seam width of self-made electrode increases 1.1～2.2mm, the penetration increases 0.1～0.6mm. In the reinforcement of seam value, self-made electrode is slightly lower than the TS202.3. In the metallurgical analysis, with the increase of self-made cored electrode in number, in the weld, the martensite decrease,, in hot zone, the toughness is improved with the increase of granular bainite, in the grain region, the grain size of self-made rod is uneven.In the weld zone, the TS202 hardness is highest, the average hardness of 338HV, self-made cored wires increase lead to the hardness value decrease from 280HV to 192HV in the weld zone, but higher than the base metal hardness. The maximum hardness of welded joints appears in coarse grain area, changes in the value is erratic.4. The current needs to increase with the increase of the number of flux corde wire. The length of rod decreaes with the number of wire increase, the purpose is to avoid porosity defects and increase density of flux in the manufacturing process.