Selection of electrodes is usually based on the chemical composition of steel, mechanical properties, crack resistance and other aspects of the requirements, while the shape of the welded structure, working conditions, such as the force situation to be fully considered, if necessary, weldability test to take certain technological measures, Ensure welding quality.
1, generally according to the steel strength level to select the corresponding electrode, taking into account the welding structure size, shape, groove, working conditions, the situation of force, a comprehensive analysis and selection of the required electrode and process measures.
2, the cooling speed of the weld quickly, so that the strength increased, easy to crack the weld situation, the choice of a lower strength than the parent metal welding rod.
3, case of multi-plate welding or normalizing after welding and other circumstances, to prevent the phenomenon of weld strength is too low.
4, the same strength level of acidic or alkaline electrode selection, the main consideration of the workpiece structure and shape, thickness, working conditions, the general requirements of good plasticity, high impact toughness, cracking ability, to use alkaline (low hydrogen )welding rod.
5, for carbon steel and low alloy steel or low alloy steel and low alloy steel between the dissimilar steel welding, the general use of lower strength grade steel corresponding to the electrode.
6, the welding of medium carbon steel, due to the higher carbon content of steel, increasing the tendency of welding cracks, the choice of low hydrogen electrode. And to take warm-up, slow cooling and after-heat measures.
7, cast steel welding, high carbon steel casting, and the thickness of large, complex shape, easy to produce welding cracks, when the cast steel is more prominent when the content of alloying elements, the general selection of low hydrogen electrode, must take pre Heat and the corresponding process measures.
8, to provide the current range of welding electrodes, for reference purposes only. Workpiece preheating can be 5% ~ 15% lower than normal current. When using DC, it can be about 10% smaller than AC. Vertical welding and back welding are about 10% ~ 15% smaller than welding current.