Super-Long Life Fatigue Properties of Aluminum Alloy Die-casting Related with Internal or Surface Defects

Rheo-die casting (RDC) based on LSPSF (low superheat pouring with a shear field) rheocasting process has been exploited. In case of secondary die casting aluminum alloy YL112, LSPSF allowed for preparation of sound semi-solid slurry in 15-20s that fully meet the production rate of HPDC, the primary α-Al exhibiting a mean equivalent diameter of 70 μm and shape factor of 0.93, without any entrapped eutectic. Compared to conventional HPDC, RDC improves microstructures in castings. Secondary solidification of semi-solid slurry takes place uniformly throughout the entire cavity, producing an extremely fine and uniform microstructure. The experimental results show the RDC 380 alloy has much improved integrity and mechanical properties, particularly elongation, and heat treatment can be used to enhance the mechanical properties.

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Failure Analysis of Rheocast Cylinder Head Covers of Hypereutectic Al–Si Alloys

Journal of Failure Analysis and Prevention ◽

10.1007/s11668-020-01110-6 ◽

2020 ◽

Author(s):

Jian Feng

Keyword(s):

Heat Treatment ◽

Surface Morphology ◽

Service Time ◽

Shot Peening ◽

High Frequency ◽

Cylinder Head ◽

Die Casting ◽

Fatigue Properties ◽

Homogeneous Distribution ◽

Engine Components

AbstractThe purpose of the present study is to determine the cause of failures of semisolid rheocast cylinder head covers of hypereutectic modified LM30 alloys. The covers, manufactured by rheocasting, a process that consists of the incorporation and homogeneous distribution of the reinforcements in semisolid metal (SSM) before die casting, were shot-peened after heat treatment to increase the fatigue resistance. However, these engine components failed during operation after a short service time. The major flaws were located by radiography. The microstructure was controlled by metallography. Significant interactions between shot peening and surface/subsurface contaminants were identified by surface morphology and fractography. The fatigue properties of hypereutectic alloys were investigated by a high-frequency vibrophore. It was identified that the failure was related to the cleanliness of SSM as well as the rheocasting process. Recommendations were given to prevent the recurrence of similar failures.

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Newly Developed Heat Resistant Magnesium Alloy by Thixomolding®

Materials Science Forum ◽

10.4028/www.scientific.net/msf.488-489.287 ◽

2005 ◽

Vol 488-489 ◽

pp. 287-290 ◽

Cited By ~ 1

Author(s):

Tadayoshi Tsukeda ◽

Ken Saito ◽

Mayumi Suzuki ◽

Junichi Koike ◽

Kouichi Maruyama

Keyword(s):

Aluminum Alloy ◽

Magnesium Alloy ◽

Magnesium Alloys ◽

Room Temperature ◽

Elevated Temperatures ◽

Die Casting ◽

The Other ◽

Heat Resistant ◽

Higher Temperature ◽

Better Than

We compared the newly developed heat resistant magnesium alloy with conventional ones by Thixomolding® and aluminum alloy by die casting. Tensile properties at elevated temperatures of AXEJ6310 were equal to those of ADC12. In particular, elongation tendency of AXEJ6310 at higher temperature was better than those of the other alloys. Creep resistance of AXEJ6310 was larger than that of AE42 by almost 3 orders and smaller than that of ADC12 by almost 2 orders of magnitude. Fatigue limits at room temperature and 423K of AXEJ6310 was superior among conventional magnesium alloys.

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