19 jul. 2017
Some nitrogen has been present in steel as long as steel-making has taken place. This has been unintentional and, in practice, there have been no means of removing or controlling the nitrogen concentration. It was not until the advent of modern process metallurgical techniques such as AOD, VOD and CLU during the 1970’s that nitrogen could be added to the steel melt in a controlled way and nitrogen, therefore, became an important alloying element.