Some material definition

1.     Creep test: Creep may be defined as the slow plastic deformation of a material under a constant stream.  

2.     Fatigue failure: It may be defined as the failure of material due to a repeatedly applied stress. The stress required to bring such a failure may be much less than that required to break the material in a tensile stress. 

3.     Yield point: Minimum stress required to produce strain. In a tensile test, the stress level at which deformation of test piece first occurs, this stress is yield point.

4.     O.1% proof steel: The stress necessary to produce a certain amount of permanent set in metals that do not exhibit a yield point. It is stress producing an extension of 0.1%. in specifying, proof stress in a tensile test the percentage of the elongation is the amount of non-proportional deformation.