Dear Debtanay,

You have to assign high value of film coefficient at bottom side of the welding plates to compensate heat loss in backing plate. For the high value of film coefficient you can refer published journals

Hello Abhishek

Thanks for your suggestions. I already tried the same but still, I am facing the same problem. Most probably my problem is with boundary conditions. With a certain type of boundary condition that I am using, I am getting high temperature in the tool and workpiece and with the other one, my elements are excessively distorting.