Key points of basic knowledge of welding process

Low hydrogen type welding rod, also known as alkaline welding rod. Alkaline welding rod has strong desulfurization and dephosphorization capabilities, and the coating has a dehydrogenation effect. The hydrogen content of the welded joint is very low, so it is also called low hydrogen type welding rod. The weld of the alkaline welding rod has good crack resistance and mechanical properties, but the process performance is poor. It is generally welded with a DC power supply and is mainly used for welding important structures (such as boilers, pressure vessels and alloy structural steel, etc.).

What preparations should be made before the first layer of flat welding with alkaline low-hydrogen electrodes?
(1) The electrodes need to be dried at 350~380 degrees and constant temperature for 1 hour. The electrodes should be placed in an insulation tube and taken out at any time.
(2) Before welding, the oil stains in the weld groove should be purged with a flame. For the larger gap section of the groove and the weld nodules on the inner side of the positioning weld outside the weld groove, grinding wheels should be used.
(3) The welding current should be connected to the positive electrode and the weldment to the negative electrode. When the DC is reversed, the electrode is the anode and the molten pool is the cathode. The electrode melts quickly and the penetration depth is small. The blowing force of the arc is soft, the combustion is stable, and the metal transition molten pool splashes less, which can avoid the generation of hydrogen pores. If the DC positive connection is used, the electrode is at the cathode and the weldment is at the anode. The weldment molten pool area is deep and the temperature is high. The metal transition molten pool is unstable, the blowing force of the arc is large, the combustion is unstable, the metal transition molten pool splashes more, and the tendency to generate pores increases.