Alternate Value:

Alternate values are sometimes used alternatively of yield strength. Many of these are temporarily described below.

1. The yield point, determined through the divider method, includes an observer along with a pair of dividers watching for visible elongation among two gage marks on the specimen. While visible stretch occurs, the load at that instant is recorded, and the stress corresponding to which load is calculated.

2. Soft steel, while tested in tension, often displays peculiar features, called as a yield point.  A drop in the load (or sometimes a constant load) is observed while the strain continues to rise if the stress-strain curve is plotted.  Finally, the metal is strengthened through the deformation, and the load increases within additional straining.  A high point on the S-shaped portion of the curve, whereas yielding starts, is called as the upper yield point and the minimum point is the lower yield point. That phenomenon is extremely troublesome in contain deep drawing operations of sheet steel.  Steel continues to elongate and to become thinner at local areas whereas the plastic strain initiates, leaving unsightly depressions known as stretcher strains or "worms."

3. The proportional limit is described as the stress at that the stress-strain curve first deviates from a straight line. Following this limiting value of stress and the ratio of stress to strain is constant, the material is said to obey Hooke's Law (stress is proportional to strain). A proportional limit commonly is not used in specifications since the deviation starts so gradually which controversies are sure to arise as to the exact stress at that the line starts to curve.

4. The elastic limit has previously been described as the stress at that plastic deformation starts. This limit cannot be determined from the stress-strain curve. A method of determining the limit would have to involve a succession of slightly rising loads along with intervening finished unloading for the detection of the first plastic deformation or "permanent set."  Such as the proportional limit or its determination would conclude within controversy. Elastic limit is used, therefore, as a descriptive, qualitative term.

In various conditions, the yield strength is used to recognize the permitted stress to in which a material could be subjected. For elements that have to withstand high pressures, such as those used in pressurized water reactors (PWRs), which criterion is not adequate.  For cover these conditions, a maximum shear stress theory of failure has been incorporated into The American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, Rules for Construction of Nuclear Pressure Vessels. A maximum shear stress theory of failure was originally reason for use in the U.S. Naval Reactor Program for PWRs. That will not be elaborates in this text.