Hydrogen embrittlement is a process which leads to the decrease in the ductility of a metal due to the presence of hydrogen atoms. It is caused by the diffusion of hydrogen atoms into the metal and their subsequent absorption into the metal lattice, resulting in the formation of atomic hydrogen within the metal crystal structure. This process can lead to the weakening of material strength, cracking, and fractures in the metal, as well as a decrease in the metal’s ductility.