Keyword: «welded joint»

The article studies the influence of low-frequency modulated current welding modes on the structure of welded joints of structural low-alloy steels. The welding process takes place in low climatic temperatures. For a comparative analysis of the structure, DC welding was also carried out. The structure was characterized by optical and scanning electron microscopy. The features of the influence of the modulation frequency of the welding current and the ambient temperature on the microstructure of welded joints have been revealed. Comparative structural analysis showed that the low-frequency range of pulsed changes in the energy parameters of the mode provides the most favorable structure of welded joints made of low-alloy steels. The optimal pulse repetition frequency (1.67 Hz) was revealed when welding with modulated current in a low-temperature environment (up to -45°C), at which the most favorable dispersed structure of the welded joint is formed.

Developed and proposed technology for welding a saddle branch to a polyethylene pipe makes it possible to work at low ambient temperatures without constructing temporary heated shelters. Experimental welding took place in the natural conditions of the city of Yakutsk. Quality control by pull-off tests of the obtained welded joints showed the effectiveness of the developed technology for welding a saddle branch to a polyethylene pipe.