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

  1-12

  Gábor Terdik

  Ákos Meilinger

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  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.