Quenched and Tempered Steel
A carbon or alloy steel with a medium carbon content optimized for the combined quenching and tempering process to guarantee high toughness combined with good strength.
Quenched and tempered steel is a medium-carbon steel with some alloying elements that give it a good combination of strength and toughness after quenching and tempering. When welding, the main problem is that rapid cooling in the heat-affected zone can create hard, crack-prone microstructures. Therefore, you usually need to preheat the steel and slow down the cooling after welding, for example with a cover layer or in a furnace. If you cool the weld too fast, the material becomes brittle and can crack; if you cool it too slowly, you lose strength. The key is to hit the right preheat temperature and control the cooling rate – then the weld will hold.