ASTM F436 thru hardened structural flat washers are used under bolt heads or nuts to increase the bearing surface area, or to offer protection so that the nut or bolt can be rotated without distortion of the bearing surface. They are designed for general purpose and structural use with bolts, nuts, studs, and other internally and externally threaded fasteners. Dimensional specifications are governed by ASTM F436. Dimensionally comparable to the low carbon SAE Washer, but manufactured from a higher grade of steel and heat treated. F436 washers are suitable for use with many fastener grades including B7, B16, L7, and A325 and A490 structural bolts. Also used with fasteners covered in A354 and A449.