Cold-Work Tool Steel

Cold work steel has plenty of carbon in it, which makes it hard and wear-resistant. When welding, that's the classic: the heat ruins the hardness. If the part gets too hot, the structure coarsens and the cutting edge is done for. You have to keep heat input as low as possible and let the steel cool slowly after welding. If the component gets hot in service later, you're on the wrong track with this material anyway.