الکترود-WELDING ELECTRODE

الکترود ،سیم جوش، 
 

AWS - E6013

الکترود


When selecting welding electrodes, one should do according to the requirements of their chemical composition, mechanical properties, crack-resistance performance and, at the same time, analyze comprehensively all kinds of factors like welding structures, steel plate thickness, working conditions, stress status, welder performance, etc. If necessary, do some welding experiments, work out corresponding technical measures, and then decide and select the right kinds of welding electrodes

 

 To weld carbon steel, the electrodes whose strength corresponds with the steel are generally selected. And if the steel is complex-structured, thick, rigid, dynamic-loaded and hard-to-weld, low-hydrogen electrodes with good plasticity, high impact toughness and good crack-resistance are generally selected. If the welding position has already been specified, special electrodes should be selected, such as electrodes for vertical down position welding, electrodes for backing weld, etc. In order to improve welding efficiency, iron powder electrodes can be selected 

 If the weld cools quickly, its strength increases and cracks easily appear, the electrodes whose strength is one degree lower than the base metal can be selected. For dissimilar steel welding between low-carbon steel and low-alloy steel, the electrodes corresponding with the steel at low strength grade are generally selected. And, to take low-alloy steel into consideration, low-hydrogen type is suitable

 

 To weld medium-carbon steel, due to the high carbon content of steel, which increases the welding crack tendency, low-hydrogen electrodes are generally selected, with some measures like preheating and slow cooling and corresponding welding technology adopted

 

Cast steel is hard-to-weld, with high carbon content, thick and big, complex-structured, which easily leads to its high crack tendency, especially when there are quite a number of alloying elements in the cast steel. Low-hydrogen electrodes are generally selected, with some measures like preheating and slow cooling and corresponding welding technology adopted

 

 

 In order to guarantee welding quality, weld bonds of work pieces should be cleaned and oil stains, rust, moisture, paint, smut and so on. Should not be left, which is especially significant for using low-hydrogen electrodes

 

 

 For low-hydrogen electrodes, they must be baked under 350℃ for an hour before welding and used as soon as baking is completed, or some flaws like blowholes, slag inclusions, cracks will appear. Generally cellulose type electrodes do not need baking. If they are affected with damp, they should be baked before welding under the temperatures specified in the specification. However, high temperatures will damage their welding performance

 

The welding currents specified in the specification are reference values, however, in actual operations, they can vary according to different situations. For example, for the preheating of work pieces, the welding current can be 5%~15% lower than the normal current. The currents of vertical position welding and overhead position welding can be 10%~15% lower than that of downhand welding. Direct currents can be about 10% lower than alternating currents. When using direct current welders, pay attention to the polarity of welding specified in the specification. Otherwise, it will influence the welding technology

  

 Generally low-hydrogen electrodes should not be baked over and over again so as to prevent the coating becoming crisp and falling off