Non-standard Alloy Steel Socket Head Screws. Made of alloy steel, these low-profile screws are nearly twice as strong as their stainless steel counterparts. With half the height of a standard socket head, these low-profile screws fit in tight spaces but are weaker than standard socket heads. Length is measured from under the head.
Black-oxide steel screws are mildly corrosion-resistant in dry environments. Zinc-plated steel screws have a zinc outer layer that protects the steel under them from rust, extending the life of the screw.
Class 8.8 steel screws are medium-strength, so they’re strong enough for use with most machinery and equipment. Class 10.9 steel screws are high-strength—they are at least 25% stronger than Class 8.8. Use them for high-stress applications such as valves, pumps, and automotive suspensions.
Coarse threads are the industry standard; choose these screws if you don’t know the pitch or threads per inch. Fine threads are closely spaced to prevent loosening from vibration. They are not compatible with coarse threads.
Screws that meet ASTM A574 comply with specifications and testing requirements for material quality.
DIN screws meet international standards for materials and dimensions.
