Vetyembrittämistä

Vetyembrittämistä, a Finnish term, translates to "hydrogen embrittlement" in English. It describes a process where certain metals, particularly high-strength steels, absorb hydrogen atoms. This absorption can significantly reduce the ductility and toughness of the metal, making it prone to brittle fracture under stress, even at relatively low stress levels.

The hydrogen atoms can enter the metal through various mechanisms. One common source is during electroplating processes, where hydrogen is generated as a byproduct. Acid pickling, a process used to clean metal surfaces, can also introduce hydrogen. In some high-temperature applications, hydrogen may be present in the operating environment. Once inside the metal, hydrogen atoms can migrate to areas of stress concentration, such as microvoids or grain boundaries.

The presence of these hydrogen atoms interferes with the normal deformation mechanisms of the metal. They can pin dislocations, hindering plastic deformation, and can also weaken the atomic bonds between metal grains. This leads to a premature and often catastrophic failure without significant yielding. The severity of hydrogen embrittlement depends on factors like the type of metal, its strength, the presence of stress, the temperature, and the concentration of absorbed hydrogen. Mitigation strategies include careful material selection, controlled manufacturing processes to minimize hydrogen absorption, post-treatment processes like baking to remove absorbed hydrogen, and the use of protective coatings.