Hi Anil,
Firstly you put question for subontracting process and which control key will be take for further process? after that your question had changed asked for refurbishment process.
So, find this link for refurbishment process and take control key PM02 ,if material send from plant to vendor permises.
http://help.sap.com/saphelp_46c/helpdata/en/fe/67ec5c9d6f11d189b60000e829fbbd/frameset.htm