Mechanical Properties

The fracture toughness master curve refers to a way of interpreting fracture toughness at which an alternative reference temperature is applied.

Fracture toughness is defined as the resistance of a flawed material to further extensions to the flaw, to the extent that the propagation of the flaw becomes rapid and unlimited. Fracture toughness is measured in terms of stress intensity factor (k). Such flaws can include weld defects, cracks, voids, discontinuities in design, metallurgical inclusions, and more.

Maximum Allowable Operating Pressure (MAOP)  maximum pressure at which a pipeline or segment of a pipeline may be operated.

Reference temperature refers to the temperature at which the stress of a material is zero.

The strain-hardening exponent (n), also known as the strain-hardening index, is measured through Hollomon’s equation. 

A strength coefficient (k) is closely related to the strain-hardening exponent and usually calculated in reference to each other.

Plastic strain is defined as the level of stress at which a material does not return to its original size and shape after being deformed. In a true-plastic strain curve, the relationship between the plastic strain and stress of a material is illustrated. 

True stress can be derived by taking the applied load divided by the cross-sectional area. A true-stress strain curve gives us a picture of the relationship between the stress and strain of a material. 

Ductility is defined as the level of tensile stress a material can take before becoming deformed. This damage is typically measured in the decrease of the cross-section area without a complete fracture occurring. 

Ultimate strength refersto the maximum stress a material or object can withstand without being pulled or stretched. This value can be obtained by dividing the cross-section area of the material by the stress being placed on the material.  

Yield strength is defined as the stress level at which a material starts to strain or deform irrecoverably. The yield strength of an object gives us insight into the stress level at which its deformation is plastic.