To Apply Patterning to Represent Section Graphics

Create or add an element template.
In the Element Templates dialog, add template properties by right-clicking on New Template and choosing Add > Pattern/Hatch > Area Patterning Properties.
The Pattern/Hatch Settings are added to the Properties pane and apply the current default values that would be used by the hatch or pattern tools.
(Optional) Edit the properties.
Select the solid(s) that will be cut by the section.

You do not apply hatching or patterning to section graphics. Instead, you associate a pattern with the solid that will be cut, and the pattern is applied to all section graphics produced from that solid. To associate a pattern with a solid, use an element template.
Apply the element template to the solid.

All sections through the solid(s) display with the specified hatch or pattern.