Fortune Hardware Co., LTD

Standard:  DIN125/DIN126, GB/T97.2-1985/GB/T97.2-1985, ISO7089/ISO7090

Material： SUS301,304,18/8,0Cr18Ni9,X5CrNi1810,X10Cr13,410S21,if you need to use other stainless steel, please let us know.

Heat Treatment: None for normal, If you have special hardness requirement, please let us know.

Surface Hardness：220HV is Normal, 750HV max after Quench with SUS410

Finish：None.

Refer to document as below:
    
Stainless Steel Flat Washer.pdf 
 

 Stainless Steel Flat Washer intended for the general use under the head of a bolt or nut in order to provide a smooth bearing surface and distribute the fastener load over a wider surface area. Available in many sizes, specifications, grades, and finishes.

 

"Stainless Steel" - With the addition of 12% chromium to iron, stainless steel is formed. The chromium protects the iron against most corrosion or red colored rust; thus the term "stainless steel". The ability of stainless to form a thin layer of protection on its outside surface, called a "passive film", is its most important characteristic in preventing corrosion.

 

"18-8" - 300 series stainless steel having approximately (not exactly) 18% chromium and 8% nickel. The term "18-8" is used interchangeably to characterize fasteners made of 302,302HQ,303,304,384, XM7, and other variables of these grades with close chemical compositions. There is little overall difference in corrosion resistance among the 18-8 types, but slight differences in chemical composition do make certain grades more resistant than others against particular chemicals or atmospheres.

 

Austentic - Refers to 300 series stainless, the most popular of the stainless alloys accounting for 85%-90% of stainless fasteners sold Named for sir Robert Williams Austen, an English metallurgist, austentic stainless is a crystal structure formed by heating steel, chromium, and nickel to a high temperature where it forms the characteristics of 300 series stainless steel.