Hex Bolts Fastener Mart Bolts, Screws, Nuts, Anchors ...
Grade 2 flat washers should only be used with Grade A307 and Grade 2 hex bolts. Use hardened flat washers with bolt Grades 5 and 8. Because Grade 2 flat washers are made of soft, low carbon steel, they will "yield" (compress, cup, bend, etc.) under the higher torque values normally associated with Grade 5 and 8 bolts.