Magnetic Roller Submerged Arc Welding Numerical Simulation And Experimental Study On Heat Source

Submerged arc welding technology needs small equipments investment and easy to implement. For these advantages, many countries have used this technology to repair rollers. Columnar crystals become larger easily during submerged arc welding process, especially when multilayer surfacing welding , columnar crystals could cause bad damage, which reduce the cracking resistance. In this subject, heat source of submerged welding was studied based on numerical simulation and experiments.With the development of computer technology, numerical simulation of welding is already available for actual surfacing with optimized welding process parameters. Through the computer model, the input process parameters are obtained by analyzing welding temperature field, stress field distribution, and can view the internal nodes of the temperature and stress distribution. When the welding voltage U = 30V, welding current I = 340A, welding speed V = 397mm / min, magnetizing current I = 270A, frequency of the magnetic field f = 5Hz welding stress will be the smallest. Welding belongs to the local high temperature heating, while the heat is concentrated in the vicinity of the weld, causing sharp temperature change of high temperature zone formation of gradient, leading to larger residual stress after welding. Welding residual stress is the main cause of crack strength, so I use this group of optimal parameters for test. In order to improve the appearance of welding seam and welding quality, this thesis will introduce the low frequency magnetic field into the roller submerged arc welding process, according to the characteristics of big welding current, large pool and long duration in submerged arc welding process. The old electromagnetic stirring device is improved, output power is increased, the magnetic field parameters adjustment range is broaden. The improved electromagnetic stirring device can satisfy the requirement of submerged arc welding. Through the electromagnetic stirring change welding droplet transfer mode, the welding process can be improved, so can the performance of surfacing layer.When the welding current I = 340A, welding speed V = 397mm/min, magnetizing current I = 270A, frequency of the magnetic field f = 5Hz hardness will be the largest value, microstructures of surfacing layer get refinement most obviously and directivity of columnar crystals is disarranged. At the same time for verification on the morphology of weld, was relatively consistent results.