No, the yield stress of a material does not always decrease with a decrease in strain rate. In some materials, the yield stress may remain constant or even increase with a decrease in strain rate.
The relationship between strain rate and yield stress can be affected by various factors such as temperature, microstructure, and strain hardening of the material.
Yes, strain rate can affect the overall strength of a material. A higher strain rate can lead to an increase in the strength of some materials, while a lower strain rate may result in a decrease in strength.
Strain rate can significantly influence the mechanical properties of a material, such as yield stress, tensile strength, and ductility. Different strain rates can result in different material behaviors, making it an essential factor to consider in material design and testing.
It is difficult to determine a maximum strain rate at which the yield stress of a material can decrease as it can vary depending on the material's properties. However, in most cases, there is a limit to how much the yield stress can decrease with an increase in strain rate.