Creep Technical Publications
92. The Influence of Microstructure and Carbide Particles on the Creep Behaviors of PM Alloys: Microstructure, related porosity, and the presence of strengthening inclusions such as carbides are known to influence the strength behaviors of PM alloys. Since an understanding of these relationships will be required if PM alloys are to be successfully used in demanding automotive applications, studies were conducted to evaluate their influence on design properties such as creep. Elevated tensile creep tests at 6770C (12500F) and 35Mpa (5Ksi) were conducted to determine steady state creep rates and deformations of 434L and 304L alloys. While both materials exhibited acceptable behaviors for automotive applications, relatively large differences between creep rupture times were observed. Moreover, a large variance in the creep rupture time was observed for the 304L alloy. It is believed that the observed variations in creep behaviors between the 434L and 304L alloys can be attributed to porosity variations, the existence of a silicon oxide layer along the grain boundaries of the 304L samples, and the presence of chromium carbide within the 434L specimens.