The Effect of Inverse Macro-Segregation on Fatigue Behavior of Die-Cast AM60 Magnesium Alloy

2005 ◽  
Vol 488-489 ◽  
pp. 713-716 ◽  
Author(s):  
Soon Gi Lee ◽  
Gautam R. Patel ◽  
Arun M. Gokhale
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Magnesium Alloy ◽  
Fatigue Resistance ◽  
Surface Segregation ◽  
Fatigue Behavior ◽  
Eutectic Phase ◽  
Mg Alloys ◽  
Die Cast ◽  
Alloy Castings

The normal and inverse solute macro-segregation are known to occur in Al and other nonferrous alloy castings and have been well studied and documented. However, these phenomena have not been investigated in the high-pressure die-cast Mg-alloys. Consequently, the effects of macro-segregation on the mechanical properties of cast Mg-alloys have not been characterized. The objective of this contribution is to investigate the effects of inverse macro-segregation and porosity on the fatigue behavior of high-pressure die-cast AM60 alloy. It is observed that the inverse macro-segregation of eutectic phase at the cast surfaces adversely affects the fatigue behavior: the fatigue resistance decreases substantially due to the presence of the surface segregation.

Effect of Friction Stir Processing on Microstructure and Mechanical Properties of a HPDC Magnesium Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 1735-1740 ◽  
Author(s):  
Emanuela Cerri ◽  
Paola Leo
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Magnesium Alloy ◽  
Friction Stir Processing ◽  
Eutectic Phase ◽  
X Rays ◽  
Nugget Zone ◽  
Friction Stir ◽  
Rotation Rates ◽  
Die Cast

A high pressure die cast (HPDC) magnesium alloy was friction stir processed (FSP) at high rotation rates with different advancing speeds. The AZ91 plate was 3 mm thick and the pin had a truncated cone tip. The friction stir processing induced the disappearance of porosity (typical of the HPDC process) in the nugget zone but some tunnel defects were introduced. The presence of characteristic FSP zones is not obvious due to the low plastic deformation of this alloy. The stirred zone is very narrow around the tool and this makes the FSP difficult to occur in the whole thickness of the plate. Microhardness values and electrical conductivity are sensitive to stirred zone and differences arise according to FSP parameters. The grain size is refined and homogenized by FSP due to partial solubilisation and disappearance of the eutectic phase surrounding Mg-alpha. X-rays diffractometry was performed on FSP samples to index phases and calculate peak shifts of Mg-alpha.

The Mechanical Properties of Rheo-High Pressure Die Cast Al-Mg-Si-(Cu) 6xxx Series Alloys

2014 ◽  
Vol 217-218 ◽  
pp. 61-66 ◽  
Author(s):  
Heinrich Möller ◽  
Pfarelo Daswa ◽  
Gonasagren Govender
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Hot Tearing ◽  
Limited Information ◽  
Die Cast ◽  
Near Net Shape ◽  
Alloy Castings ◽  
Semi Solid ◽  
Si Content ◽  
6Xxx Series

Near-net shape casting of wrought aluminium alloys has proven to be difficult due to a tendency towards hot tearing during cooling. Rheo-high pressure die casting (R-HPDC), has been shown to be an effective method of producing near-net shape wrought aluminium alloy castings. Limited information is available regarding the mechanical properties of age-hardenable wrought Al-castings produced by semi-solid metal forming. The purpose of this study is to investigate the effects of chemical composition and natural pre-ageing on the hardness and mechanical properties of rheo-HPDC 6xxx series Al-Mg-Si-(Cu) alloys in the T6 temper condition. The effects of the addition of Cu, as well as the (Mg+Si) content and Mg:Si ratio of the alloys are quantified. Alloys that are included are Cu-free 6004 and 6082, as well as Cu-containing 6013, 6111 and 6066. It is shown that the addition of Cu and excess Si result in higher hardness and strength. Natural pre-ageing has a significant effect (positive for 6004 and negative for the others) on the T6 properties. Good strength values can be achieved, but ductility is dependent on factors such as hot tearing during casting and incipient melting during solution heat treatment.

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