This online example demonstrates the capability to make RadGrid columns static when scrolling and static headers are enabled. This is quite useful when you want to make part of the columns data visible at all times for the end users when having horizontal scrollbar for navigation.
To enable this grid functionality, merely set the ClientSettings -> Scrolling -> FrozenColumnsCount property of the control which determines the count of columns (starting from the leftmost column) which will be statically positioned when you drag the horizontal scroll in the grid. This feature is functional with hierarchy/grouping presentation as well.

Further details about the frozen columns feature of RadGrid you can find in the relevant article from the product documentation:
Frozen columns