Lanthanum Role in the Graphite Formation in Gray Cast Irons
The present paper reviews original data obtained by the authors from recent separate publications with additional unpublished data, specifically concerning the Lanthanum (La)’s role in the solidification pattern and graphite formation in gray cast irons. Iron melting at 0.018–0.056%S, a 3.7–4.1% car...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-12-01
|
| Series: | Minerals |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2075-163X/10/12/1146 |
| _version_ | 1797543943225737216 |
|---|---|
| author | Eduard Stefan Iulian Riposan Mihai Chisamera Stelian Stan |
| author_facet | Eduard Stefan Iulian Riposan Mihai Chisamera Stelian Stan |
| author_sort | Eduard Stefan |
| collection | DOAJ |
| description | The present paper reviews original data obtained by the authors from recent separate publications with additional unpublished data, specifically concerning the Lanthanum (La)’s role in the solidification pattern and graphite formation in gray cast irons. Iron melting at 0.018–0.056%S, a 3.7–4.1% carbon equivalent (CE) and less than 0.005%Al<sub>residual</sub> are inoculated with La-bearing FeSi alloys at different associations with other inoculating elements. Complex Al-La small inclusions as possible better nucleation sites for (Mn,X)S compounds and La-Ca presence in the body of these sulfides, which possibly provide better nucleation sites for flake graphite, are identified in 0.026%S cast iron. At a lower sulfur content (0.018%S), La,Ca,Al-FeSi alloy still has a high efficiency, but more complex La-bearing alloys are recommended for a higher dendritic austenite amount (LaBaZrTi–FeSi) or for lower eutectic recalescence (LaBaZr–FeSi). La has limited but specific benefits at 0.05–0.06%S irons, including favorable graphitizing factors (a higher amount of graphite precipitated at the end of solidification), lower eutectic recalescence, and a lower value of the first derivative at the end of solidification. When La,Ca,Ba,Al,Zr,S-FeSi treatment (0.035%S base iron) is used, Scanning Electron Microscopy (SEM) analysis finds that the first formed micro-compound is a complex Al-silicate (Zr,La,Ca,Ba presence), which supports the nucleation of the second compound (Mn,Ca,La)S type. At the sulfide-graphite interface, there is a visible thin (nano size) Al-silicate layer (O-Al-Si-Ca-La system), which is more favorable for graphite nucleation (it has better crystallographic compatibility). La is identified in all three important areas of nucleants (the first is formed oxidic nucleus, the second is nucleated Mn-sulfide and the third is a sulfide-graphite interface), thereby increasing the efficiency of graphite nucleation sites. |
| first_indexed | 2024-03-10T13:52:39Z |
| format | Article |
| id | doaj.art-c9e2618660da499d803f8865b9003a9f |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T13:52:39Z |
| publishDate | 2020-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-c9e2618660da499d803f8865b9003a9f2023-11-21T01:59:09ZengMDPI AGMinerals2075-163X2020-12-011012114610.3390/min10121146Lanthanum Role in the Graphite Formation in Gray Cast IronsEduard Stefan0Iulian Riposan1Mihai Chisamera2Stelian Stan3Materials Science and Engineering Faculty, Politehnica University of Bucharest, 060042 Bucharest, RomaniaMaterials Science and Engineering Faculty, Politehnica University of Bucharest, 060042 Bucharest, RomaniaMaterials Science and Engineering Faculty, Politehnica University of Bucharest, 060042 Bucharest, RomaniaMaterials Science and Engineering Faculty, Politehnica University of Bucharest, 060042 Bucharest, RomaniaThe present paper reviews original data obtained by the authors from recent separate publications with additional unpublished data, specifically concerning the Lanthanum (La)’s role in the solidification pattern and graphite formation in gray cast irons. Iron melting at 0.018–0.056%S, a 3.7–4.1% carbon equivalent (CE) and less than 0.005%Al<sub>residual</sub> are inoculated with La-bearing FeSi alloys at different associations with other inoculating elements. Complex Al-La small inclusions as possible better nucleation sites for (Mn,X)S compounds and La-Ca presence in the body of these sulfides, which possibly provide better nucleation sites for flake graphite, are identified in 0.026%S cast iron. At a lower sulfur content (0.018%S), La,Ca,Al-FeSi alloy still has a high efficiency, but more complex La-bearing alloys are recommended for a higher dendritic austenite amount (LaBaZrTi–FeSi) or for lower eutectic recalescence (LaBaZr–FeSi). La has limited but specific benefits at 0.05–0.06%S irons, including favorable graphitizing factors (a higher amount of graphite precipitated at the end of solidification), lower eutectic recalescence, and a lower value of the first derivative at the end of solidification. When La,Ca,Ba,Al,Zr,S-FeSi treatment (0.035%S base iron) is used, Scanning Electron Microscopy (SEM) analysis finds that the first formed micro-compound is a complex Al-silicate (Zr,La,Ca,Ba presence), which supports the nucleation of the second compound (Mn,Ca,La)S type. At the sulfide-graphite interface, there is a visible thin (nano size) Al-silicate layer (O-Al-Si-Ca-La system), which is more favorable for graphite nucleation (it has better crystallographic compatibility). La is identified in all three important areas of nucleants (the first is formed oxidic nucleus, the second is nucleated Mn-sulfide and the third is a sulfide-graphite interface), thereby increasing the efficiency of graphite nucleation sites.https://www.mdpi.com/2075-163X/10/12/1146gray cast ironLa inoculationgraphite nucleationstructureLaS |
| spellingShingle | Eduard Stefan Iulian Riposan Mihai Chisamera Stelian Stan Lanthanum Role in the Graphite Formation in Gray Cast Irons Minerals gray cast iron La inoculation graphite nucleation structure La S |
| title | Lanthanum Role in the Graphite Formation in Gray Cast Irons |
| title_full | Lanthanum Role in the Graphite Formation in Gray Cast Irons |
| title_fullStr | Lanthanum Role in the Graphite Formation in Gray Cast Irons |
| title_full_unstemmed | Lanthanum Role in the Graphite Formation in Gray Cast Irons |
| title_short | Lanthanum Role in the Graphite Formation in Gray Cast Irons |
| title_sort | lanthanum role in the graphite formation in gray cast irons |
| topic | gray cast iron La inoculation graphite nucleation structure La S |
| url | https://www.mdpi.com/2075-163X/10/12/1146 |
| work_keys_str_mv | AT eduardstefan lanthanumroleinthegraphiteformationingraycastirons AT iulianriposan lanthanumroleinthegraphiteformationingraycastirons AT mihaichisamera lanthanumroleinthegraphiteformationingraycastirons AT stelianstan lanthanumroleinthegraphiteformationingraycastirons |