High carbon steel has high carbon content and poor weldability. Its welding has the following characteristics:
(1) The thermal conductivity is poor, and a significant temperature difference is generated between the welded portion and the unheated portion. When the molten pool cools rapidly, internal stresses generated in the weld are likely to form cracks.
(2) It is more sensitive to quenching, and the martensite structure is easy to form in the near seam area. Due to the effect of the tissue stress, cold cracks are generated in the near seam region.
(3) Due to the influence of high temperature welding, the grain growth is fast, the carbide tends to accumulate on the grain boundary, the weld is weak, and the strength of the welded joint is lowered.
(4) High carbon steel is more susceptible to hot cracking than medium carbon steel when welded.