... buildings, civil span. Structural steel tower masts and other friction-link project. I bolt steel companies choosing the material quality, production ... A490 A325M A490M1- Raw material : 40Cr,35Crmo2-Surface hardness: HRC:34-38,38-42,only for bolt3-Surface hardness ... 1 1/4'' 5.High tensile Description(TC bolt) Torshear type high strength bolts for steel structureMaterialAlloy steel ,carbon steel, ...