Grain Growth Inhibition Phase

When welding, it's important that the grains formed during cooling stay fine. You achieve this by keeping the heat input under control and not staying too long in the critical temperature zone. If the grains become too coarse, the material loses toughness and becomes brittle. Especially with higher-strength steels, you need to pay attention to proper cooling to avoid coarse structures. If you run the weld too hot and too slow, you'll quickly get a coarse structure and the risk of cracking increases.