Nitrogen diffusion in the heat-affected zone

Nitrogen in steel is a double-edged sword: it increases strength, but also makes the structure brittle and prone to cracking. When welding, you must be careful not to introduce too much nitrogen into the weld pool, otherwise you'll get hard, brittle spots in the weld. When working with nitrogen-alloyed steels, use a filler material that matches the base material in nitrogen content. And remember: the hotter the weld pool, the more nitrogen it can absorb, so keep the heat input in check.