Why the query scan all the partitions?
Your column is of type CHAR(6). Your filter is of type VARCHAR (perhaps counter intuitive, but that what the constant literal '200706' is). The rules of Data Type Precedence dictate that the comparison occurs using the type with higher precedence, ie. the VARCHAR type. This is a different type than the partitioning function, therefore you do not get partition elimination. 

Try this instead:

select count(*)
from T (nolock)
where Month = CAST('200706' as CHAR(6));


Your plan should get a partitioning elimination filter.