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1993
Journal Article
Titel
Fatigue strength and applications of cast aluminium alloys with different degrees of porosity.
Alternative
Schwingfestigkeit von Aluminiumgußlegierungen unterschiedlicher Porosität
Abstract
This paper reports on the influence of porosity on constant- and variable-amplitude fatigue of an age-hardened alloy G-Al-7Si-0.6Mg wa and a non-age-hardened alloy G-Al-11Si-Mg-Sr. Both alloys reveal a cycling hardening. The age-hardened alloy is suitable for finite fatigue life and variable-amplitude fatigue applications, but not the non-age-hardened alloy because of the flat course of its S-N curve. Despite the large differences between the static strength properties the endurance limit properties are similar. If the degree of porosity is increased from 0 to 8, fatigue strength is reduced in the unnotched condition by about 17 % for both alloys. However, in the notched condition the age-hardened alloy displays a reduction of 7 % but the non-age-hardened material a drop of 20% due to its lower yield stress. The influence of the thickness of the solidified cross-section on fatigue strength in the porous condition could not be determined. Porosity can be tolerated even in safety parts, but not in highly stressed fatigue-critical areas.