The effect of sulfur on the weldability for P355GH steel plate

Sulfur often exists in the form of iron sulfide in P355GH steel plate, and distributed in a network at the grain boundaries, thus significantly reducing the toughness of P355GH steel.

The eutectic temperature of iron plus iron sulfide is low (985°C). Therefore, during hot working, since the start temperature of processing is generally 1150-1200°C, and the eutectic of iron and iron sulfide has been melted, resulting in cracking during processing, this phenomenon called "hot brittleness of sulfur".

This property of sulfur causes hot cracks in P355GH steel during welding. Therefore, the content of sulfur in P355GH steel is generally strictly controlled. The main difference between ordinary carbon steel, high-quality carbon steel and advanced high-quality steel lies in the amount of sulfur and phosphorus.