Stainless Steel Machine Screw, Pan Head, Phillips Drive, MIL-SPEC, 1/4"-20, 2-1/2" Length (Pack of 25)
Machine Screws, also referred to as Machine Bolts, are often used with nuts or driven into tapped holes.  They come in a variety of head types and drive styles, but are generally available in smaller sizes.Stainless steels are used for their corrosion resistance, high-temperature strength, scaling resistance, and low-temperature toughness.  These properties account for their extremely wide use in practically every industry.  Austenitic Stainless Steels are alloys of iron and carbon that contain between 16% and 30% Chromium, a maximum of 0.15% carbon, along with Nickel (or Manganese), and other alloying elements.  The chromium, which helps develop a passive surface oxide film, provides corrosion resistance in stainless steels.   Austenitic Stainless Steels are designated by a 3 digit SAE Stainless Steel Grade beginning with the number 3 (e.g.  304, 316).  Another common naming convention for Austenitic Stainless Steels are 18/8, 18/10, 18/0, etc.  where the 18 refers to the % of Chromium and 8 to the % of Nickel contained in the material.    Pan head fasteners have a low, large cylindrical head with a high rounded top edge for higher tightening torques - these fasteners are often recommended to replace older head styles such as round, binding, or truss-head where possible.  The Phillips drive style was originally designed so that the driver would slip out under extreme torque, preventing over-tightening and damage to the fastener or the material.A threaded fastener's size name includes information about the major external diameter, followed by the threads per inch, which indicates if it is coarse or fine.  Coarse threads are better when working with brittle materials; they are sturdier and are easier to thread and unthread compared to fine.  Coarse threading also allows for thicker coatings and platings.