... , switch & crossing bolts, high tensile strength bolts for rail bridges etc.3, Various type and sizes of tie plates, clamps, fastenings, gauge ... ,12.Bolts and nuts:Mechanical Properties1, Material: 40 Cr.2, Tensile strength: Mpa quartile 1220 (magnitude 12.9) .3, Tension loading: N ... hardness:HRC:29-33 only for nut4- There shall be no crack and harmful defect on bolt and nut5-Surface dealing : Black, ...