Steel abrasives are

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

particles that are used as

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 by friction. While finishing a material often means polishing it to gain a smooth, reflec ...

peening In metallurgy, peening is the process of working a metal's surface to improve its material properties, usually by mechanical means, such as hammer blows, by blasting with shot (shot peening), or focusing light (laser peening). Peening is norma ...

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 is the process of forming grains or granules from a powdery or solid substance, producing a granular material. It is applied in several technological processes in the chemical and pharmaceutical industries. Typically, granulation invo ...

") 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 An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...

, contaminants, etc.).

Recyclability and environmental impact

The recyclability of steel shot and grit ranges between 2000 and 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 The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The ...

(400 to 850 on the

Vickers hardness The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness t ...

scale).

Industrial applications

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 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. The steel shots are generally employed in shot blasting machines, first made by US-based company Wheelabrator in 1932. In

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, shot blasting machines were built around the 1950s
Qinggong Machinery
is one of the earliest manufacturers in that industry.

Stone cutting

Steel grit is used in cutting hard stones, such as

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

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

Shot peening

Shot peening Shot peening is a cold working process used to produce a compressive residual stress layer and modify the mechanical properties of metals and composites. It entails striking a surface with shot (round metallic, glass, or ceramic particles) with ...

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 The automotive industry comprises a wide range of company, companies and organizations involved in the design, Business development, development, manufacturing, marketing, and selling of motor vehicles. It is one of the world's largest industry ...

Construction Construction is a general term meaning the art and science to form objects, systems, or organizations,"Construction" def. 1.a. 1.b. and 1.c. ''Oxford English Dictionary'' Second Edition on CD-ROM (v. 4.0) Oxford University Press 2009 and com ...

Metallurgy Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys. Metallurgy encompasses both the sc ...

Petrochemical industry The petrochemical industry is concerned with the production and trade of petrochemicals. A major part is constituted by the plastics (polymer) industry. It directly interfaces with the petroleum industry, especially the downstream sector. Compan ...

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.