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Creep behavior can be split into three main stages. In primary, or transient, creep, the strain rate is a function of time. In Class M materials, which include most pure materials, primary strain rate decreases over time. This can be due to increasing dislocation density, or it can be due to evolving grain size. In class A materials, which have ...
• The creep resistance of hard and brittle materials was significantly influenced by small amounts of strain, although visible creep cavities or cracks were not observed. • Laboratory-damaged or ex-service materials showed negligible primary or secondary creep during subsequent testing.
Oxidation or corrosion resistance is provided by elements such as aluminium and chromium. Superalloys are often cast as a single crystal in order to eliminate grain boundaries, which decrease creep resistance (even though they may provide strength at low temperatures). The primary application for such alloys is in aerospace and marine turbine ...
Moreover, value of is related to the resistance toward the necking. Usually, the value of is at the range of 0-0.1 at room temperature and as high as 0.8 when the temperature is increased. By combining the 1) and 2), we can create the ultimate relation as below:
Primary Creep: the initial creep stage where the slope is rising rapidly at first in a short amount of time. After a certain amount of time has elapsed, the slope will begin to slowly decrease from its initial rise. Steady State Creep: the creep rate is constant so the line on the curve shows a straight line that is a steady rate.
In viscoplasticity, the development of a mathematical model heads back to 1910 with the representation of primary creep by Andrade's law. [9] In 1929, Norton [10] developed a one-dimensional dashpot model which linked the rate of secondary creep to the stress. In 1934, Odqvist [11] generalized Norton's law to the multi-axial case.
Creep behavior can be described in three stages: primary, secondary, and tertiary creep. When modeling solder, secondary creep, also called steady state creep (constant strain rate), is often the region of interest for describing solder behavior in electronics. Some models also incorporate primary creep.
It may also vary with time (most often decreasing) in a process known as resistance creep. Electrical contact resistance is also called interface resistance, transitional resistance, or the correction term. Parasitic resistance is a more general term, of which it is usually assumed that contact resistance is a major component.