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Grade

The classification of the washer based on its material properties, such as strength and hardness, which determines its suitability for specific applications.

6/6

This is a specific designation of a polyamide or nylon plastic. This lightweight material doesn't have corrosion problems, is non-magnetic, non-corrosive, non-toxic, non-flammable and non-conductive. It is much weaker than the SAE standard grade 2, yet great in low strength applications where weight is at a premium.

18-8

A general designation for the most common and popular stainless steel, (300 Series) referring to the 18% chromium and 8% nickel. It's strength has a range from the middle to low end of the grade scale. All 300 series stainless steel share the ratio of chromium to nickel with varying other elements improving different properties. It has higher corrosion resistance than the 400 series stainless steels and it is non-magnetic.

316

The second most common stainless steel grade, this material is stronger than grade 2, slightly weaker than grade 5,or generally as strong as medium to low carbon steel. It is on the low middle end of the grade scale. It is used in more severe corrosive environments than 304 stainless steel, as such it is used in more industrial settings, like process chemicals, textiles, bleaches, salt water and rubber. It is also used in surgical implants. The DIN/ISO denotation for a very similar grade is A4-70.

A2

A type of the most common stainless steel grade. It is comparable in strength to grade 2 materials, yet slightly weaker and easy to weld. This grade is always metric. The ASTM denotation for very similar grade is 304. The corrosion resistance and ease of fabrication are why this grade is used in food industry machines, appliances, architectural trim and aquatic fasteners.

A4

The second most common stainless steel grade, this material is stronger than grade 2 and generally as strong as medium to low carbon steel. It is on the low middle end of the grade scale. This grade is always metric. The ASTM denotation for a very similar grade is 316.

A4-80

Made from the second most common stainless steel grade, this material is stronger than grade 2 and generally as strong as medium to low carbon steel. It is also slightly stronger than its A4-70 relative. It is on the low middle end of the grade scale. This grade is always metric. The ASTM denotation for a very similar grade is 316.

Alloy 20

A nickel alloy, this grade is similar to 316 stainless steel (A4-70), which is just below grade 5 on the SAE scale. This puts it on the middle to low end of the grade scale. It was developed to resist sulphuric acid and has good corrosion resistance as well. Applications include use in the food, pharmaceutical, and plastic industries.

C-110

This essentially pure copper grade is used for it pleasing red/pinkish coloring or for its heat transfer properties. It is a highly ductile and conductive.

Case Hardened

This surface hardening process allows the interior of the fastener to maintain fracture resistance, while increasing the outer shell strength of the steel. This process is used to increase strength of medium carbon steels.

HV300

This is a German designation of washer hardness. This grade offers a high degree of hardness with a Rockwell hardness of C29.8 to C40.8. Use with high strength cap screws and bolts.

Thru-Hardened

Although not a true "Grade" designation, this term is often used to denote a washer that is compatible with higher grades of steel such as Grade 5 or Grade 5 hex cap screws and nuts. This hardening process of heating and rapid quenching in water or brine requires the steel's composition to be greater than 0.30% carbon by mass. It makes the metal very strong, yet brittle.

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