Skip to main content
SpringerLink
Log in

Effect of Mold Type on the Microstructure and Tensile Properties of A356 Alloy

  • Published:
International Journal of Metalcasting Aims and scope Submit manuscript

Abstract

The present study was performed on castings obtained from A356 alloy melts subjected to different melt treatments (degassing, modification, grain refining). The castings were prepared using three different processes/molds: lost foam, ASTM standard metallic, and end-chill refractory molds. An examination of samples sectioned from the cylinder head/lost foam casting showed that the secondary dendrite arm spacing (SDAS) depends on the sample location in the cylinder head, with bolt boss and combustion chamber sections exhibiting SDAS values of 52 and 86 µm, respectively, versus 26 µm for the ASTM metallic mold samples, and from 25 to 85 µm with increasing distance from the end-chill, along the height of the refractory mold. Grain refining (Al-4 %B) leads to redistribution of porosity in the casting, as the AlB2 particles of the grain refiner act as sites for the precipitation of hydrogen gas bubbles, resulting in finer pores. This observation is independent of the mold type. In the presence of modifier, Sr–B interaction causes loss in the available Sr and B for modification and grain refining, resulting in a heterogeneous distribution of the eutectic silicon particles. Although increasing the solidification rate reduces the percentage porosity, it also leads to segregation of hydrogen at the solid/liquid interface in the case of directional solidification obtained with the end-chill mold, so that the porosity is the outcome of the solidification rate and the hydrogen content. The tensile properties of the A356 alloy are controlled by the size and morphology of the eutectic silicon particles more than by the addition of grain refiner. The difference in tensile properties obtained using the three molds is essentially attributed to % porosity (shrinkage, gas, and presence of residual pyrolysis) and SDAS. The use of proper melt treatments and the ASTM standard metallic (tensile test bar) mold could produce strength values that are 170 % higher than that obtained from the lost foam castings.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10
Figure 11
Figure 12
Figure 13
Figure 14
Figure 15
Figure 16
Figure 17

Similar content being viewed by others

References

  1. D. Apelian, S. Shivkumar, G. Sigworth, Fundamental aspects of heat treatment of cast Al–Si–Mg alloys. AFS Trans. 97, 727–742 (1989)

    Google Scholar 

  2. S. Shivkumar, C. Keller, D. Apelian, Aging behavior in cast Al–Si–Mg alloys. AFS Trans. 98, 905–911 (1990)

    Google Scholar 

  3. L. Bäckerud, G. Chai, J. Tamminen, Solidification Characteristics of Aluminum Alloys, Vol. 2: Foundry Alloys, AFS/Skan aluminium, Des Plaines, IL, USA (1990), pp. 71–84

  4. C.H. Cáceres, C.J. Davidson, J.R. Griffiths, The deformation and fracture behaviour of an Al–Si–Mg casting alloy. Mater. Sci. Eng. A A197, 171–179 (1995)

    Article  Google Scholar 

  5. Q.S. Hamed, R. Elliot, The dependence of secondary dendrite arm spacing on solidification conditions-I. Untreated Al–7Si–0.4 Mg alloys. Cast Metals 6, 36–41 (1993)

    Article  Google Scholar 

  6. D.A. Granger, E. Ting, Structure in Directionally Solidified Aluminum Foundry Alloy A356 (The Metallurgical Society, Cincinnati, 1998)

    Google Scholar 

  7. R.E. Reed-Hill, R. Abbaschian, Physical Metallurgy Principles (PWS-KENT Publishing Co., Boston, 1992)

    Google Scholar 

  8. R.E. Spear, G.R. Gardner, Dendrite cell size. AFS Trans. 71, 209–215 (1963)

    Google Scholar 

  9. J.C. Jaquet, W. Hotz, Quantitative description of the microstructure of aluminum foundry alloys. Cast Metals 4, 200–224 (1992)

    Article  Google Scholar 

  10. A.M. Samuel, F.H. Samuel, Modification of iron intermetallics by magnesium and strontium in Al-Si alloys. Int. J. Cast Met. Res. 10, 147–157 (1997)

    Article  Google Scholar 

  11. S. Shivkumar, D. Apelian, H. Brucher, Melt cleanliness in die cast Al alloys, in: Transaction of the 16th International Die Casting Congress and Expositions, Detroit, MI (1991), pp. 143–152

  12. A.M. Samuel, F.H. Samuel, Use of the reduced pressure test in the measurement of the hydrogen content in the foundry of composites, in: Advances in the Production and Fabrication of Light Metals and Metal Matrix Composites, Edmonton, AL, Canada (1992), p. 701

  13. A.M. Samuel, F.H. Samuel, H.W. Doty. Influence of melt treatment and solidification parameters on the quality of 319.2 end-chill aluminum castings, in: 4th International Conference on Molten Aluminium Processing, Orlando, FL, USA (1995)

  14. E. Samuel, B. Golbahar, A.M. Samuel, H.W. Doty, S. Valtierra, F.H. Samuel, Effect of grain refiner on the tensile and impact properties of Al–Si–Mg cast alloys. Mater. Des. 56, 468–479 (2014)

    Article  Google Scholar 

  15. M.F. Ibrahim, E.M. Elgallad, S. Valtierra, H.W. Doty, F.H. Samuel, Metallurgical parameters controlling the eutectic silicon characteristics in Be-treated Al–Si–Mg alloys. Materials 9(2), 1–17 (2016)

    Article  Google Scholar 

  16. ASTM E155 2015 Edition, September 1, 2015

  17. D.A. Lados, D. Apelian, L. Wang, Solution treatment effects on microstructure and mechanical properties of Al-(1 to 13)%Si–Mg cast alloys. Metall. Mater. Trans. B 42B, 171–180 (2011)

    Article  Google Scholar 

  18. A.M.A. Mohamed, F.H. Samuel, A review on the heat treatment of Al–Si–Cu/Mg casting alloys, in: Heat Treatment: Conventional and Novel Applications (InTech, Rijeka, Croatia, 2012)

  19. L. Ratke, D. Uffelmann, W. Bender, P.W. Voorhees, Theory of Ostwald ripening due to a second-order reaction. Scr. Metall. Mater. 33, 363–367 (1995)

    Article  Google Scholar 

  20. H. Chen, L’effet du taux de refroidissement, modification au strontium, traitement thermique du liquide et la mise en solution sur les caractéristiques des particules du silicium eutectique et les propriétés de traction de l’alliage A356. Université du Québec à Chicoutimi. Chicoutimi : 2005. Mémoire de maîtrise

  21. A.M. Samuel, F.H. Samuel, Effect of melt treatment, solidification conditions and porosity level on the tensile properties of 319.2 end chill aluminium castings. J. Mater. Sci. 30(19), 4823–4833 (1995)

    Article  Google Scholar 

  22. G. Boudreault, A.M. Samuel, F.H. Samuel, H.W. Doty, Microstructural observations of porosity in A319.2 alloy: effect of mold type/cooling rate, in Proceedings of the One Hundred Third Annual Meeting: March 13–16, 1999, (American Foundrymen’s Society, 1999), pp. 207–216

  23. K. Matsuda, T. Naoi, K. Fujii, Y. Uetani, T. Sato, A. Kamio, S. Ikeno, Crystal structure of the β” phase in an Al–l.0mass% Mg2Si–0.4mass% Si alloy. Mater. Sci. Eng. A262, 232–237 (1999)

    Article  Google Scholar 

  24. G.A. Edwards, K. Stiller, G.L. Dunlop, M.J. Couper, The precipitation sequence in Al–Mg–Si alloys. Acta Mater. 46, 3893–3904 (1998)

    Article  Google Scholar 

  25. K. Matsuda, Y. Sakaguchi, Y. Miyata, Y. Uetani, T. Sato, A. Kamio, S. Ikeno, Precipitation sequence of various kinds of metastable phases in Al-1.0mass% Mg2Si-0.4mass% Si alloy. J. Mater. Sci. 35, 179–189 (2000)

    Article  Google Scholar 

  26. M. Drouzy, S. Jacob, M. Richard, Interpretation of tensile results by means of quality index and probable yield strength. Int. Cast Met. J. 5, 43–50 (1980)

    Google Scholar 

Download references

Acknowledgments

The authors would like to thank Amal Samuel for enhancing the quality of the art work used in the present study.

Author information

Authors and Affiliations

  1. Université du Québec à Chicoutimi, Chicoutimi, QC, Canada

    M. Paradis, M. H. Abdelaziz, A. M. Samuel & F. H. Samuel

  2. General Motors, Materials Engineering, Pontiac, MI, USA

    H. W. Doty

Authors
  1. M. Paradis
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. M. H. Abdelaziz
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. A. M. Samuel
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. H. W. Doty
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. F. H. Samuel
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to F. H. Samuel.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Paradis, M., Abdelaziz, M.H., Samuel, A.M. et al. Effect of Mold Type on the Microstructure and Tensile Properties of A356 Alloy. Inter Metalcast 11, 523–535 (2017). https://doi.org/10.1007/s40962-016-0102-y

Download citation

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s40962-016-0102-y

Keywords

Search

Navigation