Weld Mold 621 description: Weld Mold 621 is used as an overlay on parts subject to oxidizing and reducing atmospheres at temperatures up to 2100F. Excellent resistance to metal on metal wear, oxidation and thermal cycling. Hot work tools including impressions in forging dies, trimming dies, high temperature valves, punches, shear blades and extrusion dies. 621 will perform well on flat and contoured surfaces of dies subject to high temperature, impact and long production runs.