(a) Describe the events that take place when a specimen undergoes a tension test. Sketch a plausible (engineering) stress-strain curve, and identify all significant regions and points between them. Assume that loading continues up to fracture

The specimen elongates linearly in response to the load to its proportionality limit.The specimen undergoes non- elastic deformation to its yield point.when stretched beyond its yield point, it deforms plastically until it reaches a maximum stress limit called the Ultimate tensile strength.If loaded beyond this, the material begins necking until fracture.

Explanation:

The stress strain curve for a ductile material is shown in the attachment below.

A-B: There is a linear relationship between extension produced to load added. Point B is called the proportionality limit.

B-C: There a non linear extension of a material produced by the material in response to the applied load. Point C is called the Yield point. Beyond this, the material does not return to its original dimensions when the load is removed.

C-D. The material extends to a maximum point D, called the Ultimate tensile stress. Beyond this necking occurs.

D-E. Necking begins until the material finally fractures at point E.

Regions: A-C : Eleastic region

Regions: C-E : Plastic region

Regions: D-E : Necking region

The last one, because there is the same number of atoms (p, cl, h, and o) on both sides of the reaction.

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