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Metal Bollard Materials

Reliance Foundry's metal Bollards and post covers are cast or fabricated in a variety of high quality metals prior to machining, providing optimal strength and durability.

Cast Ductile Iron

Many of our ornamental bollard castings are available in ductile iron. Cast ductile iron (aka 'spheroidal graphite cast iron') is an alloy that is much stronger than standard cast iron; this robust metal is able to withstand the elements and physical abuse that a more brittle cast iron may not. Grey iron was the original "cast iron" or "wrought iron", and is an iron alloy characterized by its relatively high carbon content; this carbon exists as tiny, irregular flakes within the structure of the metal, leading to cast iron's characteristic brittleness. In ductile iron the graphite is in the form of spherical nodules rather than flakes, thus inhibiting the creation of cracks and providing the enhanced ductility that gives the alloy its name.

Steel

Many of our steel bollards and bollard covers are fabricated and welded as architectural metalwork highlights. These fabricated versions provide confidence for stand-alone settings, and provide superior strength when used in conjunction with security bollard installations. Steel is an alloy consisting mostly of iron, with carbon content between 0.2% and 2.1% by weight, depending on the grade. Many other alloying elements are used such as manganese, chromium, vanadium, and tungsten; varying the amount of alloying elements in the steel controls qualities such as the hardness, ductility, and tensile strength of the resulting Steel. Steel with increased carbon content can be made harder and stronger than iron, but is also less ductile.

Stainless Steel

Several of our removable bollards and bike bollards are now available in stainless steel. Stainless steel is a steel alloy with a minimum of 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel (it stains less, but it is not stain-proof). It is also called corrosion-resistant steel. There are different grades and surface finishes of stainless steel to suit the environment to which the material will be subjected in its lifetime. Stainless steel is popular to use in architectural metalwork as it helps minimize oxidation or rusting in the toughest elements.

Some of our Bollard products are available in 316 stainless steel, while others are available in 304 stainless steel;

• 304 Stainless Steel is the most versatile and most widely used stainless steel. It is readily formed into a variety of components for applications in the industrial, architectural, and transportation fields. Grade 304 stainless steel provides good corrosion and oxidation resistance; however, this stainless grade will tarnish in service. This alloy is slightly cheaper than grade 316 stainless steel, which possesses improved oxidation resistance. 304 stainless steel exhibits slightly higher strength and improved wear resistance over grade 316 stainless steel.
  

• 316 Stainless Steel is the second most widely used stainless steel stainless steels. It is readily formed into a variety of parts for applications in the industrial, architectural, and transportation fields. Grade 316 stainless steel possesses better overall corrosion resistant properties than 304, and is particularly resistant to salt water corrosion. 316 stainless steel is only about 85% as strong as 304, and is more expensive due to its improved oxidation resistance.

Cast Aluminum

Many of our decorative bollards are foundry sand cast in aluminium. This aluminum alloy is a soft, durable, lightweight, malleable, ductile metal with appearance ranging from silvery to dull grey, depending on the surface roughness. Aluminum weighs less than cast iron, an especially important consideration for decorative removable cast bollards. It is ductile, and easily machined, cast, drawn and extruded. Corrosion resistance can be excellent due to a thin surface layer of aluminum oxide that forms when the metal is exposed to air, effectively preventing further oxidation. When its finished coat is damaged, aluminum oxidizes a color that is generally more acceptable than the red rust produced by iron or steel.