<SUBMISSION>
<ACCESSION-NUMBER>0001790982-20-000141
<TYPE>4/A
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20200520
<FILING-DATE>20200522
<DATE-OF-FILING-DATE-CHANGE>20200522
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Henderson Frederick A.
<CIK>0001181685
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4/A
<ACT>34
<FILE-NUMBER>001-39162
<FILM-NUMBER>20904734
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>SUNCOKE ENERGY, INC.
<STREET2>1011 WARRENVILLE ROAD, SUITE 600
<CITY>LISLE
<STATE>IL
<ZIP>60532
</MAIL-ADDRESS>
<FORMER-NAME>
<FORMER-CONFORMED-NAME>HENDERSON FREDERICK A
<DATE-CHANGED>20020821
</FORMER-NAME>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Arconic Corp
<CIK>0001790982
<ASSIGNED-SIC>3350
<IRS-NUMBER>842745636
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>201 ISABELLA STREET
<CITY>PITTSBURGH
<STATE>PA
<ZIP>15212-5872
<PHONE>(412) 992-2500
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>201 ISABELLA STREET
<CITY>PITTSBURGH
<STATE>PA
<ZIP>15212-5872
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Arconic Rolled Products Corp
<DATE-CHANGED>20191011
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2020-05-20</periodOfReport>

    <dateOfOriginalSubmission>2020-05-22</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0001790982</issuerCik>
        <issuerName>Arconic Corp</issuerName>
        <issuerTradingSymbol>ARNC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001181685</rptOwnerCik>
            <rptOwnerName>Henderson Frederick A.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>201 ISABELLA STREET</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>PITTSBURGH,</rptOwnerCity>
            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>15212</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-05-20</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>10100</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.7021</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25947</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2020-05-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2900</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.9896</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>28847</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">This amendment is being filed to correct the number of shares actually acquired by Frederick Henderson.  The number of shares previously reported on the Form 4 to which this amendment applies resulted from an inadvertent miscalculation.</footnote>
        <footnote id="F2">The price reported in column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $10.62 to $10.75 per share. The reporting person undertakes to provide to Arconic Corporation (&quot;Arconic&quot;), any security holder of Arconic, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each price within the range set forth in this footnote.</footnote>
        <footnote id="F3">The price reported in column 4 is a weighted average price. The shares were purchased in multiple transactions at prices ranging from $10.985 to $10.989 per share. The reporting person undertakes to provide to Arconic Corporation (&quot;Arconic&quot;), any security holder of Arconic, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each price within the range set forth in this footnote.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Adam Wheeler (Assistant Corporate Secretary), by power of attorney</signatureName>
        <signatureDate>2020-05-22</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
