Fatigue & Residual Stresses on Aluminum alloys of Engine Block

1. Fatigue & Residual Stresses on
Aluminum alloys of Engine Block

2. Motivation
Common components found in an engine include pistons, camshafts, timing chains,
rocker arms, and other various parts. When fully stripped of all components, the core of
the engine can be seen. The cylinder block (popularly known as the engine block) is the
strongest component of an engine that provides much of the housing for the hundreds of
parts found in a modern engine.
Since it is also a relatively large component, it constitutes 20-25% of the total weight of an
engine. Thus, there is much interest in reducing the block’s weight.

3. Problem definition
On trying to use anther alloy “Al-Si-Mg” & 319 Al alloy instead of cast iron
we have faced two main problems
• Residual stress
• fatigue stress

4. Solution
• We will apply a heat treatment conditions (T6- T7) on the fatigue issue
• Applying solution heat treatment on the residual stresses issue

5. Effect of solution heat treatment on residual
stress in Al alloy engine blocks

6. introduction
• The impetus to develop and implement
light alloys in the automotive industry
has been mainly due to government
legislation requiring automotive OEMs
to have a corporate average fuel
economy (CAFE) of 4.2 L/100 km (54.5
US MPG) by 2025

7. Problem Definition
• Tensile residual stress in the cylinder bore region problem associated with
Al engine blocks containing cast-in gray iron cylinder liners as it can result
in cylinder distortion or engine block fracture.

8. Experiment
• Material : Aluminum alloy 319 (chemical
composition)
• Process : monochromatic neutron beam with a
wavelength of 1.55Ǻ.
• The in-situ experiments measured the change in
axial residual strain as a function of time during
soaking
• This analysis was performed on the engine blocks
prior to and following solution heat treatment

9. Solution
• Residual axial strain relieved gradually
during SHT at 470 °C with complete relief
of strain occurring following
approximately 5 h of soaking. At 500 °C,
complete relief of tensile strain occurred
in less than 0.5h

10. Fatigue of an aluminum cast alloy used in the
manufacture of automotive engine blocks

11. Experiment Conditions
• Low pressure casting process
• Samples with DAS of 30&45 µm
• AC, T6, T7 testing conditions
• Computer controlled servo hydraulic machine
• Failure analysis by scanning electron microscope (SEM)
• Optical microscope (OM) for size & type of defects recorded & distance & area of
propagation of crack
• Limit to fatigue or up to 107 cycles
• Fully revesible load (stair case scheduals)

12. Process

13. Experiment observation
• Nucleated cracks in pores close to the surface
• Failure analysis by scanning electron microscope (SEM).
• Optical microscope observes size & type of defects , distance & area of crack
propagation
• Crack nucleation
Fatigue defects are pores, due to shrinkage or gas, and second phase particles such as
intermetallic inclusions and precipitates .

14. Solution
Stabilizing (T7)
4hr-240c
Peak strength
5hr-160c
• As casted: solution heat treatment (7hr -495 c + water quenching)
Heat treatment

15. Conclusion
• Fatigue defects are pores, due to shrinkage or gas, and second phase particles such as
intermetallic inclusions and precipitates
• Microstructural refining depends on the heat transfer rate during solidification
• Crack nucleation started in large defects close to the surface & propagate following
path of high conc. of small defects
• Mg or Cu-increases mechanical properties but has tendency to crack propagation

16. [1] Rodrigo Gonzalez a, Alejandro Gonzalez, 2013, Fatigue of an aluminium cast alloy used in the manufacture of automotive
engine blocks
[2] Hieu Nguyen, 2005, Manufacturing Processes and Engineering Materials Used in Automotive Engine Blocks, School of
Engineering Grand Valley State University
[3] A. Lombardi, D. Sediakob, 2017, Effect of solution heat treatment on residual stress in Al alloy engine blocks
using neutron diffraction
[4] John Gilbert Kaufman ،Elwin L. Rooy, 2004, Aluminum Alloy Castings: Properties, Processes, and Applications,chapter 4,
4.2 dedraite arm spacing, ISBN 0-87170-803-5
References

17.  Elsevier: ScienceDirect
 Elsevier: Engineering Village
 Cambridge University Press
 Oxford University Press
 Springer
 Research Gate
 Scientific American
All of this cannot be done except by :
• Google Scholar
• Egyptian Knowledge Bank (EKB)
Research Basis

18. A Great Thanks for making up this
opportunity to make this Research & to
stand here in front of you
Dr. Islam El-galy