Wear-Resistant Special Structural Steels

Wear costs money, sometimes lots of money. Numerous structures, such as dump bodies, materials handling equipment and crushing machines, for instance, are exposed to continuous, abrasive and impact wear, which is costly. As a solution, has developed special structural steels that are highly resistant to wear and abrasion.

Wear-resistant special structural steels are, as a rule, quenched or quenched and tempered, and have a fine martensitic or martensitic-bainitic microstructure. They are produced in thicknesses up to 120 mm. Further new developments complement the range of wear-resistant steels, alongside such established, wear-resistant special structural grades as CrMnMo steels 1.8703, 1.8710, 1.8713, 1.8714, 1.8734 etc., under the trade name XAR, BRINAR, DILLIDUR, HARDOX which depends on the manufacturer.

Normalized special structural steel with hardness of 300HB is now available for structures exposed to low or moderate levels of wear, such as scrap grabs, while the HB 600 grade meets extreme wear resistance requirements. Covering a hardness spectrum from 300 to 600 Brinell, a suitable material is thus available every type of wear-exposed application.

The grade most in use at present is the steel with hardness of 400 HB which, is around five times as durable as conventional structural steel. The steels with 450HB, a further modified grade, displays even higher hardness and, at the same time, good toughness. It enables the realization of more stable and lighter structures that are also highly resistant to impact wear.

The main fields of use for the 450 HB steel include the manufacture of dump bodies and cutting edges. All the wear resisting steels contain chromium as an alloying element, which has proven very effective especially in low-acid media. The high strength ensures good shape stability and thus little deformation. Thin-plate structures allowing a greater net load are also possible. The steels have a level of toughness that guarantees a high impact resistance even under the most difficult conditions, such as subzero temperatures, for example. Wear resisting steels present no problems when subjected to flame, plasma and laser cutting. They display good weldability and low susceptibility to cold cracking.

Steels with hardness of 400 and 450 HB, with improved bending properties for commercial vehicle manufacture, are highly suitable for brake press forming and bending (dump bodies) because of their balanced alloying concept, which includes sulfide shape control. Wear resisting steels can also be supplied as plates cut from strip with close thickness tolerances of less than ±0.20 mm and the resultant processing advantages.

Wear resistant special structural steels

To complement established wear-resistant steels 400 and 500 HB, the following grades are added which offer notable benefits:

• Steel with 300 HB for structures exposed to low or moderate level of wear and abrasion - high operational efficiency and surfaces with low scale formation
• Steel with 450 HB with high hardness and, at the same time, good toughness
• Steel with 600 HB with super high hardness for extreme wear applications.

Quenched and tempered special ballistic steels

Steel is an important alternative when it comes to protecting vehicles and buildings against firearm threat. The most important criterion in these applications is achieving a high degree of security for occupants through ballistic protection. Many mills have many years of experience in the manufacture of armor plate for ballistic protection.

As a solution, ballistic steels with hardness levels up to 600 HB are available and have been used in the civilian sector for years. Thanks to our advanced steel making and rolling technologies, ballistic steels have good cold forming properties despite their high hardness and can be readily welded using ferritic and austenitic consumables.

Ballistic steels owe their high hardness and good ballistic properties to their characteristic alloying elements carbon, chromium, molybdenum, vanadium and nickel and to appropriate heat treatment by water or oil quenching and tempering. For fabricators, compliance with minimum sheet thickness and close thickness tolerances is particularly important for manufacturing and weight reasons. Material produced meeting thickness tolerances down to 0.4 mm through the use of a state-of-the-art hot strip mill.

The thickness tolerance on plate cut from hot-rolled strip is roughly half that on material produced via the four-high mill. Close thickness tolerances allow customers to provide ballistic protection and optimized weight levels.

The advantages of ballistic steels can also be favorably combined with those of fiber composite materials.

Advantages of ballistic steels can be summarized in the following way:

• Defined ballistic properties
• Very close thickness tolerances
• Maximum flatness tolerance 6 mm/m for all thicknesses
• Good cold forming properties
• Available thicknesses 3 to 150 mm
• Good weldability.