Washers provide a smooth bearing surface and are used under the head of a bolt and/or a nut. The chemical, mechanical, and dimensional requirements for hardened washers are covered under the ASTM specification F436. These washers are through hardened or carburized to add strength, but are physically smaller than a standard F844 flat washer. They are the recommended washer for any fastener other than a low carbon steel bolt.

ASTM F436 covers the chemical and mechanical requirements for hardened washers in diameters ranging from 1/4″ to 4″ inclusive. These heat treated washers are for general purpose and structural use and are suitable for use with A325 and A490 structural bolts. Additionally, they are used with bolts per A449, A354, A193, A320, F1554 and whenever specified.

ASTM F436 Grades

Type 1 F436 Carbon Steel
Type 3 F436 3 Weathering Steel

F436 Styles

Circular Round SAE pattern Sizes 1/4" through 4"
Beveled Beveled Slope 2 in 12 or 9.5 degrees for use with American standard beams Sizes 1/2" through 1-1/2"
Clipped Circular or Beveled Sizes 1/2" through 1-1/2" beveled, 1/4" through 4" circular
Beveled F436 washers are normally not available above 1". Clipped bevel washers are only usually available as specials.

F436 Mechanical Properties

Plain Finish Hot Dip Galvanized
Rockwell Hardness 38 to 45 HRC Rockwell Hardness 26 to 45 HRC

F436 Chemical Requirements

Element Type 1 Type 3
Phosphorous, max 0.040% 0.040%
Sulfur, max 0.050% 0.050%
Silicon - 0.15 - 0.35%
Chromium - 0.45 - 0.65%
Nickel - 0.25 - 0.45%
Copper - 0.25 - 0.45%