Sheet metal screws have a pointed end and widely spaced threads. They're self-starting in thin sheet metal, but in thicker materials a drilled hole is recommended.
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.
Flat head fasteners are designed to fit flush to the surface when used with countersunk holes. Length is measured from the top of the head. 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. Self-Drilling Points are excellent for use with sheet metal.
