Common Fastener Abbreviations

Fasteners often include a variety of abbreviations in their product descriptions and specifications. This guide breaks down the most common abbreviations used across screws, bolts, nuts, and washers. Whether you're shopping for stainless steel, trying to understand strength grades, or just deciphering a product label, this glossary is your go-to source.

Material Abbreviations

Abbreviation	Meaning
18-8	Stainless Steel with 18% Chromium and 8% Nickel – also referred to as 304 or A2.
A2	General-purpose stainless steel (304) used for most non-marine applications.
A4	Marine Grade Stainless Steel (316), ideal for high-corrosion environments.
AS	Alloy Steel
Ti	Titanium – Lightweight and extremely corrosion-resistant.

Specification Codes (ASTM, DIN, ISO)

Abbreviation	Meaning
ASTM	American Society for Testing and Materials
ASME	American Society of Mechanical Engineers
DIN	Deutsches Institut für Normung – Metric fastener standard (Germany)
ISO	International Organization for Standardization
RoHS	Restriction of Hazardous Substances – Environmental compliance standard
A194	Specifications for Carbon, Alloy and Stainless Steel nuts
A307	Relates to carbon, alloy and stainless steel nuts for bolts
A325	Relates to Heavy Hex Structural Bolt, similar to Grade 5
A490	Relates to alloy steel Heavy Hex Structural Bolt, similar to Grade 8
A449	Relates to Steel Hex Cap screws, bolts and studs
A563	Specification for Carbon and Alloy steel nuts
A574	Specifications for Alloy Steel Socket Head Cap screws
F436	Specifications for US and Metric Hardened Steel Washers
F594	Specifications for Stainless Steel Nuts
F835	Specifications for Alloy Steel Button Head and Flat Countersunk Socket Cap screws
F836M	Specifications for Metric 'Style 1' stainless steel nuts
F837	Specifications for Stainless Steel Socket Head Cap Screws
F912	Specifications for Alloy Steel Socket Set Screws
DIN 84	Slotted Cheese Head Machine Screw
DIN 85	Slotted Pan Head Machine Screw
DIN 94	Cotter Pin
DIN 125A	Flat Washer (without Chamfer)
DIN 125B	Flat Washer (with Chamfer)
DIN 127B	Split Lock Washer
DIN 137B	Spring Wave Washer
DIN 315	Wing Nut
DIN 439B	Finished Hex Jam Nut
DIN 911	Long Arm Hex Key
DIN 912	Hex Socket Head Cap Screw
DIN 916	Hex Socket Set Screw
DIN 931	Hex Head Cap Screw Partially Threaded
DIN 933	Hex Head Cap Screw Fully Threaded
DIN 934	Finished Hex Nut
DIN 939	Double End Stud
DIN 960	Hex Head Cap Screw Partially Threaded
DIN 961	Hex Head Cap Screw Fully Threaded
DIN 963	Slotted Flat Head Machine Screw
DIN 964	Slotted Oval Head Machine Screw
DIN 965	Phillips Flat Head Machine Screw
DIN 966	Phillips Oval Head Machine Screw
DIN 975	Threaded Rod
DIN 980V	Hex Steel Prevailing Torque Lock Nut
DIN 985	Hex Nylon Insert Lock Nut
DIN 6334	Rod Coupling Nut
DIN 6797A	External Tooth Lock Washer
DIN 6797J	Internal Tooth Lock Washer
DIN 6912	Hex Low Socket Head Cap Screw
DIN 6921	Hex Flange Head Screw
DIN 6923	Hex Flange Nut
DIN 7985	Phillips Pan Head Machine Screw
DIN 7991	Hex Flat Socket Head Cap Screw
ISO 7379	Hex Socket Head Shoulder Screw
ISO 7380	Hex Button Socket Head Cap Screw

Finish & Coating Abbreviations

Abbreviation	Meaning
BLK OX	Black Oxide – Mild corrosion resistance and matte black appearance
ZN / Zn	Zinc Plated – Economical corrosion-resistant coating
CR	Chrome – Shiny, decorative, and corrosion-resistant
Galv.	Galvanized – Coated in zinc for heavy-duty corrosion resistance

Fastener Type Abbreviations

Abbreviation	Meaning
SHCS	Socket Head Cap Screw
BHCS	Button Head Cap Screw
FHCS	Flat Head Cap Screw
SMS	Sheet Metal Screw
SSS	Socket Set Screw

Drive & Head Styles

Abbreviation	Meaning
PH / P	Phillips Drive
SQ	Square Drive (Robertson)
HX / SKT	Hex Drive / Socket
FH	Flat Head (Countersunk)
PN	Pan Head
OH	Oval Head

For even more technical resources including how to measure fasteners, conversion charts, strength data, and more, visit our full Fastener Information Page.