Steel abrasives are steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 particles that are used as abrasive

Abrasive

An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...

 or peening

Peening

Peening is the process of working a metal's surface to improve its material properties, usually by mechanical means such as hammer blows or by blasting with shot . Peening is normally a cold work process...

 media. They are usually available in two different shapes (shot and grit) that address different industrial applications.

Steel shot refers to spherical grains made of molten steel through an atomization ("granulation

Granulation

Granulation can refer to:*Granulation is the act or process of forming or crystallizing into grains*Granulation tissue, a product of healing in major wounds;*Granular synthesis, a sound synthesis method;...

") process, available in different sizes and hardnesses.

Steel grit characterizes grains with a predominantly angular shape. These grains are obtained by crushing steel shot, therefore they exhibit sharp edges and broken sections. Harder than steel shot, it is also available in different sizes and hardnesses.

Properties

Most steel abrasives are made of a high-carbon steel composition, the best compromise between mechanical properties, efficiency and durability. The most important properties for steel abrasives are hardness, grain size and shape, toughness and cleanliness (lack of oxides, contaminants, etc.).

Recyclability and environmental impact

The recyclability of steel shot and grit ranges between 2000 to 3000 cycles. Due to its high recyclability level, steel shot and grit tend to generate less waste when compared to other expendable abrasives.

Hardness

Steel shot or grit is usually available at different hardness levels, ranging between 40 and 65 on the Rockwell scale

Rockwell scale

The Rockwell scale is a hardness scale based on the indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single...

 (400 to 850 on the Vickers hardness scale).

Cleaning

Steel shot and grit are used in cleaning applications for removal of loose material on metal surfaces. This type of cleaning is common in automotive industry (motor blocks, cylinder heads, etc.).

Surface preparation

Surface preparation is as a series of operations including cleaning and physical modification of a surface. Steel shot and grit are used in surface preparation process for cleaning metal surfaces which are covered with mill scale, dirt, rust, or paint coatings and for physically modifying the metal surface such as creating roughness for better application of paint and coating.

Stone cutting

Steel grit is used in cutting hard stones, such as granite

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

. The grit is used in large multi-blade frames which cut the blocks of granite into thin slices.

Shot peening

Shot peening

Shot peening

Shot peening is a cold working process used to produce a compressive residual stress layer and modify mechanical properties of metals. It entails impacting a surface with shot with force sufficient to create plastic deformation...

 is the repeated striking of a metal surface by hard shot particles. These multiple impacts produce a deformation on the metal surface but also improve the durability of the metal part. The media used in this application is spherical rather than angular. The reason is that spherical shots are more resistant to the fracture which happens due to the striking impact.

Industrial uses

Steel shot and grit address numerous sectors since cleaning, surface preparation or shot peening applications are used by many industries as a part of their construction, renovation or repair processes. The main industrial sectors employing steel abrasives are:

• Automotive industry
  Automotive industry
  The automotive industry designs, develops, manufactures, markets, and sells motor vehicles, and is one of the world's most important economic sectors by revenue....
  
  
• Construction
  Construction
  In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...
  
  
• Metallurgy
  Metallurgy
  Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys. It is also the technology of metals: the way in which science is applied to their practical use...
  
  
• Petrochemical industry

Production

The annual steel abrasive production in the world is estimated to be above 1 million tonnes, the world’s largest producer being Winoa Group (previously known as Wheelabrator Allevard) by production and capacity.

Further reading

• Momber, A.W.; 2008, Blast Cleaning Technology, Springer Publ., Heidelberg.
• Montani, C.; 2009, Stone 2009, World Marketing Handbook, Faenza Editrice, ISBN 978-88-8138-124-1
• Schulze, V.; 2006, Modern Mechanical Surface Treatment, Wiley-VCH, Verlag GmbH & Co. KGaA, Weinheim, ISBN 3-527-31371-0

External links

• Momber, A.W.: Blast Cleaning Technology. Springer Publ., Heidelberg, 2008.
• Abrasives Used for Blasting Operations
• Industrial Applications of Steel Abrasives
• Standard Specification for Steel Abrasives
• Properties of Metal Abrasives
• Portal of Shot Peening