The mechanical properties of a casting

The mechanical properties of a casting

The mechanical properties of a casting
The mechanical properties of a casting The mechanical properties of a casting

A casting, either cast aluminum or steel, has static mechanical properties (Rm, Rp0.2, elongation) and dynamic (fatigue endurance limit) resulting from a number parameters (part design, alloying elements, ..., fineness of the microstructure).

Important factors

The main factors that impact on the mechanical properties (in both static and dynamic) of a part are:

    • The content of alloying elements which enter into the chemical composition of the piece (Al-Si7Cu3Mg for an aluminum or 2.7% C, 0.6 Si, 4.2% Ni and 1.6% for Cr cast Ni-Hard)
    • The absence of internal and external defects in the parts of mechanically stressed parts. Generally specifies an acceptable level of default (Class 1 for shrinkage in area designated for example) in the room CdC. The impact of defects on the mechanical properties can be understood finely
    • The layout of the room (for example the absence of stress concentration areas or isolated solid areas)
    • The type of microstructure obtained. For example, the shape of the graphite (flake, spheroidal, vermicular) or matrix (pearlitic, ferritic, austenitic, bainitic) for the font or shape of silicon (lamellar or acicular) or intermetallic compounds (Al-Fe-Si ) for the aluminum alloys
    • The fineness of the microstructure (due to the rate of solidification). For some applications, and specifies the DAS (Dendritic Arm Spacing) in microns for aluminum alloys
    • Micro-alloying elements in very small amounts (a few ppm to few% versus the traditional alloying elements)
    • A subsequent heat treatment that modifies the microstructure (transformation of austenite to martensite in steels for example). For Al-Si alloys, for example, it is the addition of magnesium during the heat treatment allows to increase the mechanical characteristics
    • Machining operations that can result in surface pores or cause residual stresses
    • Subsequent treatment (local shot peening or hot isostatic pressing, for example)

Source: My little blog fonderie

Last modified on Thursday, 30 January 2014 11:53

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