Definition of Stress:

While a metal is subjected to a load (force), that is distorted or deformed, no matter how strong the light or metal the load. The distortion will probably disappear when the load is removed if the load is small. The intensity, or degree, of distortion is known as strain. The strain is called elastic strain if the distortion disappears and the metal returns to its original dimensions upon removal of the load. If the distortion disappears and the metal remains distorted, the strain category is known as plastic strain. A Strain will be discussed in more detail in the further chapter.