660 Studs, non-magnetic in the annealed condition, but may become slightly magnetic by welding. Although it has the same high strength and corrosion resistance as other steels, ASTM A453 Gr. 660 Hex Head Bolts produce stronger welds due to their low carbon content. ASTM A453 Grade 660 Studs are suitable for temperature applications. This grade of fasteners is divided into A, B, C, D grades. Materials are carbon, manganese, phosphorus, sulfur, silicon, nickel, chromium, molybdenum, titanium, aluminum, vanadium, boron. ASTM A453 Grade 660 Bolts derive their strength and corrosion resistance from a combination of materials.