<SEC-DOCUMENT>0001628280-20-003215.txt : 20200309
<SEC-HEADER>0001628280-20-003215.hdr.sgml : 20200309
<ACCEPTANCE-DATETIME>20200309163722
ACCESSION NUMBER:		0001628280-20-003215
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20200305
FILED AS OF DATE:		20200309
DATE AS OF CHANGE:		20200309

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Parkinson Ray
		CENTRAL INDEX KEY:			0001551870

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09447
		FILM NUMBER:		20698434

	MAIL ADDRESS:	
		STREET 1:		27422 PORTOLA PARKWAY, SUITE 200
		CITY:			FOOTHILL RANCH
		STATE:			CA
		ZIP:			92610-2831

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KAISER ALUMINUM CORP
		CENTRAL INDEX KEY:			0000811596
		STANDARD INDUSTRIAL CLASSIFICATION:	ROLLING DRAWING & EXTRUDING OF NONFERROUS METALS [3350]
		IRS NUMBER:				943030279
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		27422 PORTOLA PARKWAY, SUITE 200
		CITY:			FOOTHILL RANCH
		STATE:			CA
		ZIP:			92610-2831
		BUSINESS PHONE:		949-614-1740

	MAIL ADDRESS:	
		STREET 1:		27422 PORTOLA PARKWAY, SUITE 200
		CITY:			FOOTHILL RANCH
		STATE:			CA
		ZIP:			92610-2831

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KAISERTECH LTD
		DATE OF NAME CHANGE:	19901122
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_158378622373439.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-03-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000811596</issuerCik>
        <issuerName>KAISER ALUMINUM CORP</issuerName>
        <issuerTradingSymbol>KALU</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001551870</rptOwnerCik>
            <rptOwnerName>Parkinson Ray</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O KAISER ALUMINUM CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>27422 PORTOLA PARKWAY SUITE 200</rptOwnerStreet2>
            <rptOwnerCity>FOOTHILL RANCH</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92610</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP - Advanced Engineering</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>1685</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>9566</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2559</value>
                    <footnoteId id="F3"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12125</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F4"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>934</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>93.22</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11191</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2020-03-05</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F5"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>665</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>93.22</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10526</value>
                    <footnoteId id="F6"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $0.01 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4437</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By Family Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Grant to the reporting person effective as of March 5, 2020 of restricted stock units under the Kaiser Aluminum Corporation 2016 Equity and Incentive Compensation Plan. All restrictions will lapse on March 5, 2023 or earlier upon the occurrence of certain specified circumstances.</footnote>
        <footnote id="F2">Includes 6,723 shares acquired pursuant to grants of restricted stock units.</footnote>
        <footnote id="F3">Shares earned upon the vesting on March 5, 2020 of certain performance shares granted to the reporting person in 2017 under the Kaiser Aluminum Corporation 2006 Equity and Performance Incentive Plan, as amended.  On March 5, 2020, the Registrant's compensation committee certified the performance shares payout multiplier based on the level of achievement by the Registrant of certain pre-established performance goals for 2017 through 2019.</footnote>
        <footnote id="F4">Shares withheld to satisfy the withholding tax obligations resulting from the vesting on March 5, 2020 of the above-referenced performance shares.</footnote>
        <footnote id="F5">Shares withheld to satisfy the withholding tax obligations resulting from the vesting on March 5, 2020 of certain restricted stock units granted to the reporting person in 2017 under the Kaiser Aluminum Corporation 2006 Equity and Performance Incentive Plan, as amended.</footnote>
        <footnote id="F6">Includes 4,787 shares acquired pursuant to grants of restricted stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Cherrie I. Tsai, with power of attorney for Raymond Parkinson</signatureName>
        <signatureDate>2020-03-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
