Journal of Materials Engineering and Performance

, Volume 27, Issue 11, pp 5992–6003 | Cite as

Effects of Mg Content on the Fatigue Strength and Fracture Behavior of Al-Si-Mg Casting Alloys

  • Ming-Ze Wu
  • Ji-Wang ZhangEmail author
  • Yan-Bin Zhang
  • Hua-Qiang Wang


In order to investigate the influence of Mg content on the fatigue properties in Al-Si-Mg alloy, uniaxial tensile tests and rotating bending fatigue tests were conducted on two Al-7Si-Mg casting alloys, with different Mg contents of 0.3 and 0.6 wt.%. The fracture surfaces of the specimens were observed by scanning electron microscopy, and the fatigue crack growth process was obtained by the replica method. The results indicate that the increase in Mg content enhances the yield strength and tensile strength of the alloy, whereas it reduces its elongation. There is an obvious knee point in the S–N curves of Al-7Si-0.6Mg alloy while that of Al-7Si-0.3Mg alloy shows continuous decrease. The fatigue strength at 5 × 105 cycles is 60 MPa for Al-7Si-0.3Mg alloy and 80 MPa for Al-7Si-0.6Mg alloy. For the two types of specimens, the fatigue failure can initiate from crystal slip and casting defects. The replica results suggest that cracks in Al-7Si-0.6Mg alloy grow more slowly than that in Al-7Si-0.3Mg alloy.


Al-7Si-Mg alloys fatigue properties fracture behavior Mg content S–N curve 



This work was supported by National Natural Science Foundation of China (Nos. U1534209, 51675445) and Fundamental Research Funds for the Central Universities (No. 2682017CX039).


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Copyright information

© ASM International 2018

Authors and Affiliations

  • Ming-Ze Wu
    • 1
  • Ji-Wang Zhang
    • 1
    Email author
  • Yan-Bin Zhang
    • 2
  • Hua-Qiang Wang
    • 1
  1. 1.State Key Laboratory of Traction PowerSouthwest Jiaotong UniversityChengduChina
  2. 2.School of Mechanical EngineeringSouthwest Jiaotong UniversityChengduChina

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