Carbon steel bar is a kind of solid long steel, and the common ones are round steel, square steel, hexagonal steel, octagonal steel.

Seamless carbon steel pipe is a kind of capillary made of steel ingot or solid billet through perforation, and then made by hot rolling, cold rolling or cold drawing.

Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or strip steel after crimping and welding. Large-diameter or thicker welded pipes are generally made of steel billets directly, while small welded pipes and thin-walled welded pipes are generally made of steel strips directly welded. The production process of welded steel pipe is simple.