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  <xs:element id="hwm_PropertyPlantAndEquipmentExcludingConstructionInProgressMember" abstract="true" name="PropertyPlantAndEquipmentExcludingConstructionInProgressMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_JPYTermLoanFacilityDue2026Member" abstract="true" name="JPYTermLoanFacilityDue2026Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_ThreePointSevenFivePercentNotesDueTwoThousandTwentyEightMember" abstract="true" name="ThreePointSevenFivePercentNotesDueTwoThousandTwentyEightMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_ThreePercentNotesDueTwoThousandTwentyNineMember" abstract="true" name="ThreePercentNotesDueTwoThousandTwentyNineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_ThreePointNinePercentNotesDueTwoThousandTwentyNineMember" abstract="true" name="ThreePointNinePercentNotesDueTwoThousandTwentyNineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_FourPointEightFivePercentNotesDueTwoThousandThirtyOneMember" abstract="true" name="FourPointEightFivePercentNotesDueTwoThousandThirtyOneMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_FourPointFiveFivePercentNotesDueTwoThousandThirtyTwoMember" abstract="true" name="FourPointFiveFivePercentNotesDueTwoThousandThirtyTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_FourPointSevenFivePercentNotesDueTwoThousandThirtyTwoMember" abstract="true" name="FourPointSevenFivePercentNotesDueTwoThousandThirtyTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_FivePointNineFivePercentNotesDueTwoThousandThirtySevenMember" abstract="true" name="FivePointNineFivePercentNotesDueTwoThousandThirtySevenMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_FourPointSevenFivePercentIowaFinanceAuthorityLoanDueTwoThousandFortyTwoMember" abstract="true" name="FourPointSevenFivePercentIowaFinanceAuthorityLoanDueTwoThousandFortyTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_OtherLongTermDebtIncludingUnamortizedDebtDiscountsAndIssuanceCosts" abstract="false" name="OtherLongTermDebtIncludingUnamortizedDebtDiscountsAndIssuanceCosts" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="hwm_A3.750NotesDue20283.900NotesDue2029And4.750NotesDue2036Member" abstract="true" name="A3.750NotesDue20283.900NotesDue2029And4.750NotesDue2036Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_A364DayRevolvingCreditAgreementMember" abstract="true" name="A364DayRevolvingCreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_A5YearRevolvingCreditAgreementMember" abstract="true" name="A5YearRevolvingCreditAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_OtherDebtMember" abstract="true" name="OtherDebtMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_DebtCovenantComplianceAxisAxis" abstract="true" name="DebtCovenantComplianceAxisAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="hwm_DebtCovenantComplianceAxisDomain" abstract="true" name="DebtCovenantComplianceAxisDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_DebtCovenantComplianceOccurrenceOfMaterialAcquisitionForTheFourConsecutiveFiscalQuartersMember" abstract="true" name="DebtCovenantComplianceOccurrenceOfMaterialAcquisitionForTheFourConsecutiveFiscalQuartersMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_LineOfCreditFacilityNumberOfExtensionRequests" abstract="false" name="LineOfCreditFacilityNumberOfExtensionRequests" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="hwm_LineOfCreditFacilityExtensionPeriod" abstract="false" name="LineOfCreditFacilityExtensionPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="hwm_LineOfCreditFacilityMaximumAdditionalBorrowingCapacity" abstract="false" name="LineOfCreditFacilityMaximumAdditionalBorrowingCapacity" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="hwm_DebtInstrumentCovenantComplianceRatioOfConsolidatedNetDebtToConsolidatedEBITDA" abstract="false" name="DebtInstrumentCovenantComplianceRatioOfConsolidatedNetDebtToConsolidatedEBITDA" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:pureItemType"/>
  <xs:element id="hwm_RecurringCostsOfManagingHazardousSubstancesAndEnvironmentalProgramsMember" abstract="true" name="RecurringCostsOfManagingHazardousSubstancesAndEnvironmentalProgramsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_IncomeTaxAndInterestMember" abstract="true" name="IncomeTaxAndInterestMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_IncomeTaxPenaltiesMember" abstract="true" name="IncomeTaxPenaltiesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_AdditionalInterestOnIncomeTaxMember" abstract="true" name="AdditionalInterestOnIncomeTaxMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_AlcoaCorporationWorkersCompensationClaimsMember" abstract="true" name="AlcoaCorporationWorkersCompensationClaimsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_ArconicCorporationEnvironmentalObligationsMember" abstract="true" name="ArconicCorporationEnvironmentalObligationsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_TaxYears2010Through2012Member" abstract="true" name="TaxYears2010Through2012Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_SeparationAgreementMember" abstract="true" name="SeparationAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="hwm_NumberOfCleanupLocations" abstract="false" name="NumberOfCleanupLocations" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="hwm_PercentageOfCostOfGoodsSold" abstract="false" name="PercentageOfCostOfGoodsSold" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="hwm_AmountCommittedUnderOutstandingSuretyBonds" abstract="false" name="AmountCommittedUnderOutstandingSuretyBonds" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="hwm_SeparationAndDistributionAgreementSuretyBondsAmountOutstanding" abstract="false" name="SeparationAndDistributionAgreementSuretyBondsAmountOutstanding" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="hwm_SupplierFinanceProgramAgreementTerminationNoticePeriod" abstract="false" name="SupplierFinanceProgramAgreementTerminationNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="hwm_GuarantorObligationsIndemnificationOfLiabilityPercentage" abstract="false" name="GuarantorObligationsIndemnificationOfLiabilityPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="hwm_InsuranceAnnualCoverageLimit" abstract="false" name="InsuranceAnnualCoverageLimit" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
