What is the difference between hydrogen bubbling, hydrogen embrittlement, and hydrogen corrosion?

Hydrogen bubbling occurs because atomic hydrogen diffuses into the metal, where it forms molecular hydrogen in the pores within the metal. Since hydrogen molecules cannot diffuse, they accumulate in the micropores, creating high internal pressures that cause the metal to bubble and even rupture. Hydrogen embrittlement occurs when atomic hydrogen enters the metal, causing severe deformation of the metal’s crystal lattice, which in turn reduces the metal’s toughness and ductility, leading to its embrittlement. Hydrogen corrosion occurs when atomic hydrogen penetrates into the metal and reacts with its components or elements; for example, hydrogen infiltrates carbon steel and reacts with the carbon in the steel to form methane, which reduces the toughness of the steel. Meanwhile, the removal of carbon from the steel leads to a decrease in its strength.