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Several different lab tests are used to represent different wear mechanisms in comparing steel materials with regard to wear behavior. The test results of the abrasive wear and impact wear of durostat® steels are clear: The use of wear-resistant steels made by voestalpine can significantly extend the service life and associated service intervals of components such as excavator buckets, tipper surfaces, conveyor chutes, wear surfaces in freight and bulk railcars, containers and concrete mixers.
The indicated results are from independent testing institutes and the Technical University in Clausthal, Germany, and the Tampere Wear Center in Finland.
Friction wheel tests were carried out pursuant to ASTM G65, in which dry or moist quartz sand is used as an abrasive between a rubber wheel and the sample to investigate the sliding abrasive wear of durostat® steels. The test describes the classic two-body wear resistance that occurs when rock materials slides off tipper surfaces, conveyor chutes or excavator shovels.
Experimental setup, ISAF Institute, Technical University of Clausthal, Germany
The results show that the main factor influencing sliding abrasive wear behavior is hardness. Martensitic steels such as durostat® made by voestalpine have a significantly higher resistance to abrasive wear than classic structural steels or microalloyed steels.
Impeller tumbler tests were performed to characterize the impact wear (Institute at Tampere University, Tampere Wear Center). An external paddle wheel (tumbler) transports the material (here: Kuru granite in 10 to 12.5 mm grain size) slow speed (30 rpm); material to be tested on the fast rotating impeller (impeller with 700 rpm) that crushes the granite by means of impact energy.
This results in the formation of furrows and troughs on the samples. These strongly deformed areas are subsequently removed by blasting with abrasive particles. Practical example Excavation work (agricultural cultivators, disc harrows), loading tippers, freight cars, bulk railcars.
Martensitic durostat steels also exhibit excellent performance of martensitic durostat® steels with respect to impact wear.
Tests were carried out in an impact simulator in order to test extreme loads on the material when tipper bodies are loaded with large pieces of rock, scrap or the like. A sled with a cone-shaped impact tip is fired with a defined energy at the sample. The resulting dent depth is measured on the test plate.
As material hardness increases, the material thickness required for the same dent depth decreases (red line in the diagram). This creates possibilities for lightweight applications. As the hardness of the materials increases, the dent depth decreases at the same material thickness (curves in the diagram). This means that even more resistant components and component groups can be achieved.
A material thickness of 10 mm would be required for S355MC to achieve a dent depth of 10 mm, while only 4 mm is required for durostat 450 to achieve the same depth. This allows lighter components and component assemblies to be produced with the same resistance to deformation, thus making it possible to economically manufacture sustainable end products with less material and fuel consumption and less CO2, yet with increased payloads.
durostat® steels exhibit good welding characteristics when using any conventional fusion welding technique. This is because of their chemical composition. The heat-affected zone of the welded joints is characterized by both the occurrence of temper softening and a lack of hardness increase as compared to the direct-quenched base material.
The extent of temper softening is directly dependent on the cooling time (t8/5). The effects of temper softening on the tensile properties across the weld are dependent on the relative width of the soft zone (ratio of soft zone width to sheet thickness) and the tensile properties of the weld metal.
Maximum hardness in the heat-affected zone (HAZ) does not exceed the hardness of the base material because of the purely martensitic microstructure. The hardness depends exclusively on carbon content. The carbon equivalent therefore only has an effect on transformation behavior and a decrease in maximum hardness as the t8/5 time increases. Vickers (HV) is used to determine the hardness values in welded joints. The hardness values in Brinell (HB) or tensile strength (Rm) can be estimated using the conversion table pursuant to EN ISO 18265, Table A.1.
Preheating is generally not required up to a sheet thickness of 6 mm.
In cases of deviation, the preheating temperature should be estimated based on EN 1011-2, C.3, Method B or SEW 088. Depending on atmospheric conditions (temperature below dew point, condensation of humidity), edge drying is recommended at least 80 °C immediately before welding.
The dew point and preheating temperature can also be calculated with the voestalpine Welding Calculator. Use the free online version on your desktop or download the app to your smartphone!
The strength properties across the weld are influenced among other factors by the strength characteristics of the selected welding filler metal.
Should the respective structure require that welding seams feature the same level of wear resistance as the base material, the cover pass can be carried out using wear-resistant welding consumables.
As compared to manual metal arc welding and gas-shielded metal arc welding, a lower tendency Temper softening in the heat-affected zone and higher strength in the weld metal are the result of concentrated energy input and the associated increased cooling rate.
All the important information about our wear-resistant steels can be found in the data sheets. We will provide you with all the details to make the ideal product selection.
