International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

The steel for the production of welded pipes must possess good weldability to achieve high efficiency and effectiveness of the production process in production lines (in line) and ground, during welding of pipes in long distance pipelines and in lower temperature conditions. The main focu of this research was on weldability assessment of API Grade X52 steel at low temperature (0°C), which is used for the production of welded pipes, respectively pipelines. Carbon equivalent (C_E), mechanical testing and metallographic analysis of the welded joint were conducted in order to assess the weldability. The results of mechanical tests and metallographic analysis show that steel API Grade X52, at low temperature (0°C) has excellent weldability, so the pipes produced can be welded in long distance pipelines, easy and unhindered, thereby ensuring high production efficiency and effectiveness.

Investigation of low carbon microalloyed API 5L X80 steels for electric-welded pipes applied in building of metallic structures of different complexity. Problems of weldability of these steels and effect of technological and structural factors on mechanical properties of weld seams have been considered. Also mechanical characteristics at cyclic loading of the steels are considered.