sql server - Cast a "-" after a varchar string and then left join another table, sql -

i working in sql server visual management studio 2012. have 2 tables. table1 has 2 columns; partnumber varchar, , dateordered smalldatetime. table2 has 2 columns, partnumber varchar, , time float. part numbers on table1 9 digits long , looks '999999999.' table2 part numbers have "-" @ end , '999999999-.' need add "-" end of part number on table1 , cross reference number table2 , time column.

select right('9', cast(varchar, partnumber)) partnumber  table1     left join table2 on table1.partnumber = table2.partnumber  dateordered between ('2015-01-01 00:00:00.000') , ('2015-05-11 00:00:00.000')    , partnumber not null 

-----------------update new code-----------

select table1.partnumber, table2.time table1 left join table2 on table2 + '-' = table1.partnumber dateordered not null 

not quite sure question, not working?:

table1.partnumber + '-' = table2.partnumber   

(not elegant way of doing things)