# Comparison of Abrasive Wear Resistance of Hardox Steel and Hadfield Cast Steel
###### Abstract
In this case, the recrystallized structure was obtained by a two-stage heat treatment that included a prolonged isothermal annealing at 510 \({}^{\circ}\)C to separate numerous pearlite grains, which, in the next stage, provided nuclei for austenite nucleation during heating to 900 \({}^{\circ}\)C. In this way, improved mechanical properties were obtained in comparison with single-stage austenitized steels. Hardox steel was first produced in 1970 by Sweden's SSAB-Oxelosund. Today, the Hardox family of steels includes 10 grades, of which 2 are designed for special applications, involving elevated operating temperatures (Hardox HiTemp) and corrosive environments (Hardox HiAce) [14]. Hardox 450 steel is recommended as a highly versatile structural steel, showing high impact strength even at reduced temperatures. It is designed for components of concrete mixers, snow cannons, containers, excavator and loader buckets, grapples, shears, garbage trucks, dump trucks, drums, asphalt rollers, combines, recycling tools, crushers and chutes. Hardox 500 and 550 steels are designed for applications where there is heavy wear with limited material design requirements, such as lining plates of crushers and feeders and hammers used in recycling. Hardox 550 offers improved durability, replacing manganese steels. Hardox 600 is suitable for heavier duty, can be cut and welded and retains satisfactory impact strength despite its high hardness. It is used, for example, in moulds for brick making, for cladding and screed plates in mineral transportation and processing, in concrete mixers and for blades and knives for recycling. Hardox Extreme steel is described as the world's hardest wear-resistant steel with a nominal hardness of 60 HRC (650-700 HBW). Tests conducted in [15] showed that Hardox Extreme steel exhibits an average strength \(R_{m}\) = 2411 MPa and \(\text{KCV}\approx\text{12 J/cm}^{2}\). It is designed for applications with extremely high wear resistance requirements, such as cladding plates. On the other hand, due to its low impact strength, some caution should be exercised when selecting Hardox Extreme steel for structural components. The key to determining areas of application for this steel is the \(R_{p0,2}\)/\(R_{m}\) value of 0.64-0.74, which is only appropriate for structures requiring a low safety factor. At the same time, it should be mentioned here that the high \(R_{p0,2}\)/\(R_{m}\) ratio is most often indicated by designers of primary machinery of the lignite mining industry as the main factor--in addition to weldability--limiting the use of high-strength, low-alloy steels for the construction of machines [3; 16; 17; 18]. In terms of weldability, a separate problem is the lowering of the mechanical properties of the above-mentioned steels, both in the weld material zone and the broad heat-affected zone, which is due to their highest mechanical indices [19; 20; 21; 22] among available steels and the maximum strength of 1000 MPa of commercially sold welding alloys. According to numerous contemporary papers [23; 24; 25; 26; 27; 28], this problem can only be eliminated by using high-quality welding consumables and by means of subsequent heat treatment. According to available tribological studies of martensitic boron steels, the condition for maintaining advantageous indices of abrasive wear resistance is to obtain a fine latch microstructure [4; 29; 30]. Moreover, the abrasion wear resistance of Hardox 500 steel can be more favourable compared to carburized 20 MnCr5 steel [31]. Hardox 500 steel also shows lower weight loss compared to S355 JR, S355J2 and AISI304 steels during tribological tests in the presence of garnet and carborundum [32]. On the other hand, in the available scientific literature, no information can be found on the results of tests to compare the abrasive wear resistance of high-manganese steels and martensitic steels.