The elastic strain for steel is about A. $$\frac{1}{{12}}$$ of strain at the initiation of strain hardening and about $$\frac{1}{{120}}$$ of maximum strain B. $$\frac{1}{2}$$ of strain at the initiation of strain hardening and about $$\frac{1}{{12}}$$ of maximum strain C. $$\frac{1}{{12}}$$ of strain at the initiation of strain hardening and $$\frac{1}{{200}}$$ of maximum strain D. $$\frac{1}{{24}}$$ of strain at the initiation of strain hardening and about $$\frac{1}{{200}}$$ of maximum strain

The correct answer is $\boxed{\frac{1}{12}}$ of strain at the initiation of strain hardening and about $\frac{1}{200}$ of maximum strain.

Elastic strain is the reversible deformation of a material when a load is applied. When the load is removed, the material returns to its original shape. Strain hardening is the strengthening of a material by

plastic deformation. When a material is plastically deformed, its microstructure changes, making it more difficult to deform further.

The elastic strain for steel is about $\frac{1}{12}$ of strain at the initiation of strain hardening and about $\frac{1}{200}$ of maximum strain. This means that when a steel rod is stretched by 1%, it will return to its original shape when the load is removed. However, if

the rod is stretched by 10%, it will not return to its original shape and will be permanently deformed.

The other options are incorrect because they do not accurately reflect the relationship between elastic strain and strain hardening.