The feasibility of refinement of Al–Zn–Mg–Si hot dip coatings by diode laser resurfacing has been demonstrated. The microstructure of the laser resurfaced coatings was characterised mainly by transmission electron microscopy and also by scanning electron microscopy. The variance of heat input results in different cooling rates and varying degrees of refinement; that is, the higher the power density, the lower the cooling rate and the larger the secondary dendrite arm spacing of α-Al dendrites. In addition, the inherent variation of chemical composition in coatings also affects the microstructure as well as phase distribution. This laser resurfacing technique has not only reduced the secondary dendrite arm spacing/α-Al dendrites but also changed the solidification path and produce different phases and microstructure in the interdendritic areas.
WallinderI. O., LeygrafC., KarlénC., HeijerickD. and JanssenC. R.: ‘Atmospheric corrosion of zinc-based materials: runoff rates, chemical speciation and ecotoxicity effects’, Corros. Sci., 2001,
43, (5), 809–816.
2.
MoraesJ., da SilvaM. M., Nogueira FilhoC. A.: Proc. of the 24th Brasilian Association of Metals Annual Congress, São Paulo, Brazil, 1969
.
3.
Anon: ‘Hot-dip galvanizing: process and products’, Brazilian Institute of Lead and Zinc Information—ICZ, Report no. 10 ICZ-Z 4.10/4.11, São Paulo, Brazil, 1972.
4.
TownsendH. E.: ‘Coutinuous hot dip coating’, 1994, 5, 339–348ASM Handbook.
5.
DalledoneE., BarbosaM. and WolynecS.: ‘Zinc–55% aluminum–1.6% silicon coating compared with zinc coating’, Mater. Perform. 1995,
34, (7), 24–28.
6.
PorterF. C.: ‘Corrosion resistance of zinc and zinc alloys’, in P. A. Schweitzer, ed., Industrial Corrosion, Marcel Dekker, New York, 1990, pp 5–9.
7.
LiH., ZhengJ. and YuD.: ‘Behavior of hot-dip 55%Al–Zn alloy coating in saltwater containing hydrogen sulfide’, Mater. Perform. 2001,
40, (5), 32–36.
8.
SelverianJ. H., MarderA. R. and NotisM. R.: ‘The reaction between solid iron and liquid Al–Zn baths’, Metall. Trans. A, 1996,
19, (5), 1193–1203.
9.
MarderA. R.: ‘The metallurgy of zinc-coated steel’, Prog. Mater. Sci., 2000,
45, (3), 191–271.
10.
MoreiraA. R., PanossianZ., CamargoP. L., MoreiraM. F., SilvaI. C. d. and de CarvalhoJ. E. R.: ‘Zn/55Al coating microstructure and corrosion mechanism’, Corros. Sci., 2006,
48, (3), 564–576.
11.
LiuQ.: China Forum on Development of Continuous Galvanized Steel Sheet, Beijing, China, 2008.
12.
YaoC., TayS. L., YangJ. H., ZhuT. and GaoW.: ‘Hop dipped Zn–Al–Mg–Cu coating with improved mechanical and anticorrosion properties’, Int. J. Electrochem. Sci., 2014,
9, (12), 7083–7096.
13.
ShibliS. M. A., MeenaB. N. and RemyaR.: ‘A review on recent approaches in the field of hot dip zinc galvanizing process’, Surf. Coat. Technol., 2015,
262, 210–215.
14.
LuoQ., LiQ., ZhangJ.-Y., LuH.-S., LiL. and ChouK.-C.: ‘Microstructural evolution and oxidation behavior of hot-dip 55 wt.% Al–Zn–Si coated steels’, J. Alloys Compd., 2015,
646, 843–851.
15.
B. S. Ltd: International Patent Application, WO2009111842A2009111841, 2009.
16.
LiS. W., GaoB., TuG. F. and ZhuG. L.: ‘Effects of Mg on the microstructure, corrosion resistance and formability of Galvalume coatings’, J. Northeastern Univ., 2013,
34, (8), 1136–1139.
17.
KomatsuA., IzutaniH., TsujimuraT., AndohA. and KittakaT.: ‘Corrosion resistance and protection mechanism of hot-dip Zn–Al–Mg alloy coated steel sheet under accelerated corrosion environment’, J. Iron Steel Inst. Jpn., 2000,
86, (8), 534–541.
18.
HondaK., YamadaW. and UshiodaK.: ‘Solidification structure of the coating layer on hot-dip Zn–11%Al–3%Mg–0.2%Si-coated steel sheet’, Mater. Trans., 2008,
49, (6), 1395–1400.
19.
B. S. Ltd: International Patent Application, WO2010102343A2010102341, 2010.
20.
DuttaM., HalderA. K. and SinghS. B.: ‘Morphology and properties of hot dip Zn–Mg and Zn–Mg–Al alloy coatings on steel sheet’, Surf. Coat. Technol., 2010,
205, (7), 2578–2584.
21.
SullivanJ., MehrabanS. and ElvinsJ.: ‘In situ monitoring of the microstructural corrosion mechanisms of zinc–magnesium–aluminium alloys using time lapse microscopy’, Corros. Sci., 2011,
53, (6), 2208–2215.
22.
B. S. Ltd: International Patent Application, WO2007134400A2007134401, 2007.
23.
MathewP. R. S. R., NolanD. and DurandetY.: ‘Parametric study of surface melting in zinc–aluminium coated steels’, Int. J. Surf. Sci. Eng., 2014,
8, 124–137.
24.
FuerschbachP. W.: ‘Measurement and prediction of energy transfer efficiency in laser beam welding’, Weld. J., 1996, 75, 24s–34s.
25.
ChenZ., PengC. T., LiuQ., SmithR. and NolanD.: ‘A new quaternary phase observed in a laser treated Zn–Al–Mg–Si coating’, J. Alloys Compd., 2014,
589, 226–229.
26.
FriaufJ. B.: ‘The crystal structure of MgZn2’, Dissertation (Ph.D.), California Institute of Technology, 1926.
27.
MadelungO., RösslerU. and SchulzM.: ‘Magnesium silicide (Mg2Si) Debye temperature, heat capacity, density, melting point’, in ‘Non-Tetrahedrally Bonded Elements and Binary Compounds I’, 1–4, 1998, Berlin Heidelberg
, Springer.
28.
LiQ., ZhaoY.-Z., LuoQ., ChenS.-L., ZhangJ.-Y. and ChouK.-C.: ‘Experimental study and phase diagram calculation in Al–Zn–Mg–Si quaternary system’, J. Alloys Compd., 2010,
501, (2), 282–290.
29.
TangY., DuY., ZhangL., YuanX. and KaptayG.: ‘Thermodynamic description of the Al–Mg–Si system using a new formulation for the temperature dependence of the excess Gibbs energy’, Thermochim. Acta, 2012,
527, 131–142.
