Grain Refinement via Nitrogen

Nitrogen acts as a ferrite former in weld metal and can prevent grain growth through the formation of finely dispersed nitrides. This has a positive effect especially in higher-alloyed steels because toughness is maintained. Too much nitrogen, however, is counterproductive – then the weld tends to porosity and cracking. So you have to keep an eye on nitrogen input via shielding gas and filler material, then it'll be fine.