when a assembly is done in solid works. and bill of material is generated there is no material section in bom even though the material is described to each part individually
no prob. First, in each part add the 'material' custom property to the custom properties list and link it to 'SW-Material' in the Value/Text Expression column.
Then in the drawing add a column in the BOM for the material (right click, insert column), and in the popup select 'custom property' and 'material'.
Save your bom and part file templates appropriately and you won't have to manually do it every time.