There is a new type of grinding media on the market. With the utilisation of VIRINA Nano Steel in the production of VIRNA Nano Steel Grinding Media, there is a revolution pending in the industry.
VIRINA Steel (VIRINA) is a steel products company that offers an industry changing, revolutionary steel product based on a proprietary, patent applied for, production process. This pioneering steel product is unlike any steel available in the marketplace. VIRINA is utilising this technology to change the grinding media marketplace by offering grinding balls that significantly outperform the “old” standards in the market.
VIRINA set out to create a high strength Nano Steel. VIRINA Nano Steel contains several elements to create a unique grain structure that is controlled through temperature and adding a specific combination of elements at levels to create and control the structure of the steel.
To create VIRINA’s unique Nano Steel formula C, SI, Mn, P, S, Ni, Cr, Mo, V, and Cu are added during the manufacturing process. Each of these elements are carefully added in specific quantities to control the grain structure and optimise the performance of the steel. The use of various amounts of each of these elements will impact the properties of the steel. For Example, Copper (Cu) and Nickel (Ni) are added in the formulation of VIRINA Nano Steel and are effective at increasing the strength of the steel, suppressive decarburization in heating and contributing to improved durability. However, if Cu and Ni amounts are excessive, workability and ductility deteriorates.
VIRNA Steel carefully controls the amount of Carbon (C) used in the manufacturing process. Carbon (C) affects the strength of the steel. It also influences the quantity and shape of the generated martensite structure and improves elongation. If a carbon amount is excessive, ductility deteriorates.
The VIRNA Nano Steel process significantly reduces the grain size to create a steel product with superior strength. VIRINA Nano Steel’s ultra fine grains have excellent hardness, ductility and collision impact resistance with very low Cr, Ti, V and Ni. VIRINA steel alloy product may generally have an average grain size of less than 1 micrometer may have an ultimate tensile strength of at least about 1084 MPa and a yield strength of at least about 783 MPa without heat treatment.
VIRINA Nano Steel has a grain size of ASTM 11-12. ASTM 11 has a density of 1 200 000 grains/mm³. This compares to a density of 23 000 grains/mm³ of an ASTM 7 high chrome grinding ball. This 52x improvement in grain structure results in a VIRINA grinding ball that has significant improvement in strength and ductility. VIRNA can produce a grinding ball that has consistent high hardness from surface to core with improved ductility properties. This allows VIRINA to outperform high chrome balls in wear rate and reducing cracking and deformation.
Typical carbon steels form a matrix of chemically dissimilar and brittle materials – carbide and ferrite. These carbides are strong, yet brittle – immovable at the grain boundaries. In a moist environment, a battery-like effect occurs between the carbides and the ferrites that destroy the steel from the inside out. This effect (a microgalvanic cell) is the primary corrosion initiator that drives the corrosion reaction.
In contrast, VIRINA alloy may (according to one embodiment) form a matrix that is substantially free of carbide, is five times as corrosion-resistant, and up to three times as strong as conventional steel.
In conventional steel, grinding media, high hardness is achieved at the expense of ductility and elasticity/tensile strength. The process through which many characteristics are achieved is usually that of adding Chromium and tempering already quenched material, thereby arriving at the desirable hardness. This creates downstream processing issues, creating a point of potential failure from cracking and deformation, and results in an inconsistent hardness between the surface and core.
In the manufacturing of VIRINA Steel, Chromium (Cr) is added to enhance the hardenability and increase the strength of the steel but in very limited amounts. Cr affects the formation of a bainite structure (that is an intermediate transformation), and is effective in obtaining a dual phased steel structure comprising ferrite and martensite. If excessive Cr is added, ductility deteriorates. Thus, a preferable Cr amount is 0.3 % or less.
Article written forWorld Cement by Virina Steel
Read the article online at: https://www.worldcement.com/special-reports/05082016/virina-steels-nano-steel-51/