Hardfacing.pptx

A Lecture by:Mostafa Hedayati MarzbaliHardfacingHard surfacing is the deposition of a special alloy material on a metallic part, by various welding processes, to obtain more desirable wear properties and/or dimensions.The properties usually sought are greater resistance to wear from abrasion, impact, adhesion (metal-to-metal), heat, corrosion or any combination of these factors.Reasons for HardfacingReduce costsProlong equipment lifeReduce downtimeReduce inventory of spare partsHard surfacing build-up can be used to returnparts to their original dimensionsHard surfacing overlay can be used by itself togive parts additional resistance to wearHard surfacing build-up and overlay can beused together to rebuild parts to size and givethem additional resistance to wearUses for HardfacingTo reclaim worn partsReplace or ReclaimThe protection of new metal parts against the loss of metal usually increases the work life of the component up to two or more timesChoosing the Hardfacing ProcessHardfacing can be applied by a number of welding processes.Selection of the most suitable welding process for a given job will depend on a number of factors including:Function of the componentBase metal compositionSize and shapeAccessibilityState of repairNumberProcesses Used in HardfacingShielded Metal Arc Welding (Covered Electrode)Flux Cored Arc WeldingSubmerged Arc WeldingGas HardfacingPowder SprayingHigh Velocity Oxy-Fuel Process (HVOF)Electric Arc SprayingPlasma Transferred Arc (PTA)Shielded Metal Arc Welding (SMAW)Advantages:Alloy availabilityMaterial thicknessWelding positionVersatilityDisadvantages:DilutionLow efficiency/depositionFlux Cored Arc Welding(FCAW)Advantages:Alloy availabilityHigh depositionDeposit integrityEasy to operateVersatilityDisadvantagesDilutionWelding positionSubmerged Arc WeldingO(SAW)AdvantagesEasily automatedHigh depositionOperator skillWeld depositShop environmentDisadvantagesAlloy availabilityWelding positionMaterial thicknessExtremely high dilutionHigh heat