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• A Slurry-Pot Abrasive Wear Test Device for Several Composite Materials

  437-444

  Hasan Muhandes

  Gábor Kalácska

  Views:

  199

  To choose the proper material for agricultural machinery we tested several materials with abrasive cloth on the pin-on-plate test device. After having the pre-results, we launched more complex abrasive testing (slurry-pot) simulating more realistic mode with soils to investigate the abrasive wear mechanism and resistance of the selected up-to-date polymeric structural materials. for this, we developed a modified slurry-pot test machine that ensures the comparability of the materials over a wide range of conditions. Through this device, several parameters could be controlled like speed, the soil particle’s hit angle on the tested surface.

• Effect of Heat Input on the Toughness Properties of S690QL Steel during Hardfacing

  1-12

  Gábor Terdik

  Ákos Meilinger

  Views:

  19

  In recent years, the use of high-strength steels in hardfacing process has become increasingly common. One typical industrial example is the case of hydraulic shears used in building demolition operations, where the components are exposed not only to significant abrasive wear but also to intense dynamic loading. The use of quenched and tempered high-strength steel grade S690QL has become particularly widespread in this field, primarily as the base material for the hardfacing applied to the most heavily loaded regions of demolition shears. However, quenched and tempered high-strength steels are highly sensitive to the effects of the welding thermal cycle, which typically cause detrimental changes in the microstructure and mechanical properties of the heat-affected zone. The thermal cycles occurring during hardfacing differ from those typical of fusion welding, and consequently, the structure and mechanical properties of the resulting heat-affected zone may also vary. In addition, the penetration depth of the hardface layer can differ, which may significantly alter the load-bearing cross-section of the high-strength steel and, thus, the in-service behavior of the component. In the experimental work, hardfaced samples were performed on S690QL base material using different levels of heat input, thereby producing varying penetration depths. The aim of the study was to determine the effect of penetration depth on the resistance of the hardfaced component to dynamic loading. The tests were carried out at both +20 °C and –40 °C. The results clearly demonstrated that samples with deeper penetration exhibited reduced toughness at both investigated temperatures. 

• The Effects of Quenching and Tempering Treatment on the Hardness and Microstructures of a Cold Work Steel

  286-294

  László Tóth

  Réka Fábián

  Views:

  421

  The X153CrMoV12 ledeburitic chromium steel characteristically has high abrasive wear resistance, due to their high carbon and high chromium contents with a large volume of carbides in the microstructure. This steel quality has high compression strength, excellent deep hardenability and toughness properties, dimensional stability during heat treatment, high resistance to softening at elevated temperatures. The higher hardness of cryogenic treated samples in comparison with conventional quenched samples mean lower quantity of retained austenite as at samples quenched to room temperature and tempered in similar condition. In the microstructure of samples were observed that the primary carbide did not dissolve at 1070°C and their net structure have not been changed during to heat treatment. During to tempering at high temperature the primary carbides have become more and more rounded. After low tempering temperature in martensite were observed some small rounded carbides also, increasing the tempering temperature the quantity of finely dispersed carbides increased, which result higher hardness. The important issues in heat treatment of this steels are the reduction or elimination of retained austenite due to cryogenic treatment.