The main ways for hydrogen to enter the liquid steel are: through the rust on the scrap steel surface (xFeO•yFe3O4•2H2O); Hydrogen in ferroalloy; Water in carburizer, deoxidizer, mulch, insulation, slagging agent (Ca(OH)2), bitumen and tar; Ladle, tundish and injection pipe undried; Spray coating of ingot mould; The mold seeps water and atmospheric water interacts with molten steel or slag to enter the steel.
The hydrogen in steel is in the form of a hydrogen atom. At high temperature, two hydrogen atoms can easily form a hydrogen molecule. Hydrogen atoms are very reactive, and in their natural state they form hydrogen molecules that are released slowly.
When hydrogen is more than 2ppm in cast iron, it is prone to porosity or general porosity, and such porosity caused by hydrogen will cause iron embrittlement. Hydrogen embrittlement occurs mainly in martensitic steel and is not very prominent in ferrite steel. In addition, hydrogen embrittleness generally increases with hardness and carbon content.
On the other hand, H can improve the permeability of steel, but also increase coerce and iron loss.
