• Stainless steel is used in construction.a stainless steel image by Yuriy Rozanov from Fotolia.com
  
  Steel is the general name given to a large range of iron alloys. There are three major types of steel: carbon steels, alloy steels, and stainless steels. Stainless steel is classified as steel having a composition of at least 10 percent chromium. Stainless steel is further classified into magnetic and non-magnetic types, each with their own mechanical properties. Mechanical properties are properties that describe how an object performs when a load or stress is applied to it. There are many forms and compositions of stainless steel, so an exact value for the different mechanical properties of stainless steel cannot be given. Instead, a range of commonly accepted values of mechanical properties are used.
  
  

Poisson's Ratio

• When an object is stretched, the length of the object increases while the thickness of the object decreases. Conversely, when an object is contracted, the length of the object decreases while the thickness of the object increases. This happens because of the conservation of matter principle, and the ratio between the contraction and elongation of an object is known as Poisson's Ratio. The lower this number, the less an object will shrink in thickness when stretched.
  
  Stainless steel is accepted to have a Poisson's Ratio between 0.27 to 0.3.
  
  

Tensile Strength

• When an object is stretched to an extreme, it begins to thin out drastically, seemingly in cones, at locations along its length. This phenomenon is known as necking and it occurs at a maximum stress or strength known as tensile strength. An object with a higher tensile stress can withstand more stress before it begins to neck.
  
  Stainless steels have accepted tensile strengths between 515 to 827 megapascals.
  
  

Yield Strength

• All objects have an elastic deformation region in which it can revert back to its original state once the load applied to it is removed. For some objects, this region may be minuscule, but nonetheless, it is there. Past a certain load, all objects enter a deformation region where it does not revert back to its original state because it has been permanently deformed. The load at which an object changes from elastic deformation to permanent deformation is known as yield strength.
  
  Stainless steels have accepted yield strengths between 207 to 552 megapascals.
  
  

Hardness

• An object's hardness is its ability to resist indentation when struck. For example, dry wall has a relatively low hardness because it can be nicked easily, but a rock has a high hardness because a large amount of strength is required to indent the rock.
  
  Stainless steels have accepted hardness values between 137 to 595 kilograms.