Page 43 - Steel Tech India eMagazine Volume October 2023
P. 43
92/ Ć ,668( Ć 2FWREHU
7KH IRUJHG DQG DLU FRROHG VWHHO ZDV VXEMHFWHG WR UH KLJK 0Q FRQWHQW VKLIWV WKH $F WHPSHUDWXUH WR DV ORZ
DXVWHQLWL]DWLRQ WR D WHPSHUDWXUH EHWZHHQ WR DV R& DQG $F LV DERXW R& 7KH KLJK 0Q
R& ZLWK D VWHS RI R& DQG KROGLQJ IRU PLQ IROORZHG FRQWHQW DOVR VKLIWV WKH & FXUYH LQ WKH &&7 GLDJUDP WR
E\ DLU FRROLQJ WR URRP WHPSHUDWXUH WR VWXG\ WKH UHYHUWHG WKH ULJKW $LU FRROLQJ LWVHOI ZLOO SURPRWH WKH IRUPDWLRQ
DXVWHQLWH WUDQVIRUPDWLRQ $57 LQ WKH VWHHO DV VKRZQ RI PDUWHQVLWH 7KH VWHHO KDV $O ZKLFK WHQGV WR
LQ )LJXUH 7KH FKHPLFDO FRPSRVLWLRQ RI WKH VWHHO ZDV VXSSUHVV WKH FDUELGH IRUPLQJ WHQGHQF\ LQ WKH VWHHO DQG
HYDOXDWHG WKURXJK 63(&752 PDNH RSWLFDO HPLVVLRQ SURPRWHV WKH IRUPDWLRQ RI DXVWHQLWH 7KH VWHHO LV QRW
VSHFWURVFRS\ 7KH KHDW WUHDWHG VDPSOHV ZHUH FXW KDYLQJ KLJK 6L FRQWHQW XQOLNH RWKHU KLJK 0Q VWHHO 7KH
LQ WKH ('0 PDFKLQH IRU WKH VWDQGDUG $670( 0 RWKHU HOHPHQWV LQ WKH VWHHO DUH UHVLGXDO HOHPHQWV WKDW
VDPSOHV IRU WHQVLOH WHVWLQJ LQ D N1 =ZLFN 5RHOO ZHUH QRW SXUSRVHO\ DGGHG 7KH 6 FRQWHQW LV DQG
PDNH WHQVLOH WHVWLQJ PDFKLQH DW D VWUDLQ UDWH RI V 3 FRQWHQW LV 5HVLGXDO &X DQG 1L DUH EHQH¿FLDO
7KH PLFURVWUXFWXUH RI WKH VWHHO ZDV HYDOXDWHG WKURXJK DV WKH\ DUH DXVWHQLWH VWDELOL]HUV 7KH &U FRQWHQW LV DOVR
+LWDFKL PDNH VFDQQLQJ HOHFWURQ PLFURVFRS\ 6(0 DQG QRW D GHWULPHQWDO HOHPHQW IRU WKH SURSHUWLHV
WKH SKDVH IUDFWLRQV ZHUH HYDOXDWHG WKURXJK 3DQDO\WLFDO 7DEOH &KHPLFDO FRPSRVLWLRQ RI WKH PHGLXP
PDNH [ UD\ GLႇUDFWLRQ ;5' 7KH SKDVH IUDFWLRQV DW PDQJDQHVH VWHHO LQ ZW
WKH GLႇHUHQW DQQHDOLQJ WHPSHUDWXUHV ZHUH HYDOXDWHG
WKURXJK 7KHUPRFDOF VRIWZDUH E DV VKRZQ LQ C M n S i S 3 $ O Cr Ni &X N
)LJXUH 0.30 0.001 0.013 0.011 0.03
$F & $F & %DVHG RQ 7KHUPR&DOF
o
o
0LFURVWUXFWXUH DQG SKDVH DQDO\VLV
7KH 6(0 PLFURJUDSKV RI WKH VWHHO DW YDULRXV
KHDW WUHDWHG FRQGLWLRQV LV VKRZQ LQ )LJXUH 7KH
PLFURVWUXFWXUH VKRZV ¿QH PDUWHQVLWH DORQJ ZLWK ZKLWH
ÀLPV\ W\SH UHWDLQHG DXVWHQLWH DORQJ WKH PDUWHQVLWH
ODWK ERXQGDULHV DQG EDLQLWH 7KH VWHHO LQ WKH IRUJHG
DQG DLU FRROHG FRQGLWLRQ VKRZV LVRODWHG ORFDWLRQV RI
EORFN\ 0 $ FRQVWLWXHQWV :KHQ WKH DV IRUJHG VWHHO LV
UH DXVWHQLWL]HG DW WKH LQWHU FULWLFDO WHPSHUDWXUH RI
DQG & DQG KHOG IRU PLQ WKHRUHWLFDOO\ WKH
o
)LJ +HDW 7UHDWPHQW &\FOH IRU WKH VWHHO DXVWHQLWH IRUPHG DV SHU )LJXUH LV DQG
austenite respectively. However, air cooling the steel
EDFN WR URRP WHPSHUDWXUH WUDQVIRUPV WKH DXVWHQLWH
EDFN LQWR PDUWHQVLWH ZKLFK JHWV WHPSHUHG RU VRPH
DPRXQW RI DXVWHQLWH PD\ WUDQVIRUPHG WR EDLQLWH $V
WKH SURSRUWLRQ RI DXVWHQLWH GHFUHDVHV LQ WKH LQWHUFULWLFDO
UHJLRQ ZLWK GHFUHDVLQJ KROGLQJ WHPSHUDWXUH WKHUH LV
SDUWLWLRQ RI FDUERQ IURP IHUULWH WR DXVWHQLWH 7KH FDUERQ
WKXV SDUWLWLRQHG GHFUHDVHV WKH 0V WHPSHUDWXUH DQG
increases the retained austenite content.
7KH ;5' RI WKH VWHHOV DW VHOHFWHG FRQGLWLRQV DW URRP
WHPSHUDWXUH LV VKRZQ LQ )LJXUH 7KH UHWDLQHG DXVWHQLWH
FRQWHQW HYDOXDWHG WKURXJK ;5' LV VXPPDUL]HG LQ 7DEOH
)LJ 3KDVH IUDFWLRQ HYDOXDWLRQ DW GLႇHUHQW WHPSHUDWXUHV 7KH DV IRUJHG DLU FRROHG VWHHO VKRZV ODWK PDUWHQVLWH
WKURXJK WKHUPRFDOF VRIWZDUH DQG UHWDLQHG DXVWHQLWH FRQWHQW RI 7KH UHYHUWHG
DXVWHQLWH WUDQVIRUPDWLRQ LV FDUULHG RXW IURP WKH IRUJHG
5(68/76 $1' ',6&866,21
DLU FRROHG FRQGLWLRQ ZKHUH WKH PLFURVWUXFWXUH LV UH
7KH FKHPLFDO FRPSRVLWLRQ RI WKH VWHHO LQ WKH SUHVHQW WUDQVIRUPHG WR DXVWHQLWH LQ WKH LQWHUFULWLFDO WHPSHUDWXUH
VWXG\ LV VKRZQ LQ 7DEOH 7KH VWHHO KDV & ZKLFK UDQJH $W WKH LQWHU FULWLFDO WHPSHUDWXUH UDQJH WKH
ensures that the steel has low carbon equivalent and DXVWHQLWH FRQWHQW LV DQG
HQVXUHV ZHOGDELOLW\ RI WKH VWHHO 7KH VWHHO KDV DXVWHQLWH UHVSHFWLYHO\ DW DQG C, the
o
0Q ZKLFK LV DQ DXVWHQLWH VWDELOL]LQJ HOHPHQW DQG WKH H[WHQW RI PDUWHQVLWH IRUPHG GXULQJ FRROLQJ GHFUHDVHV
STEEL TECH