Problem faced in butt welding simulation

Dear all,

Recently,for a butt welding the parameters I am using are: V=30 volt,I= 615 amp, eta= 0.9 and arc radius= .006m, plate size = 300 X 150 (half width)X 10 mm and a root gap of 3.5 mm. Also using the thermal element Solid70. I have taken 5 divisions( element size= 2mm) along thickness direction and 120 divisions (element size= 2.5 mm)along welding direction. What I am observing that while applying a constant heat flux (Q/Pi X r^2), the surface temperature along weld line is becoming around 4000 degree C but the surface temperature on the opposite side of the weld line is becoming around 600 degree C. Why the heat is not passing that much on the opposite side ? The material properties I have used from the following attached paper and the convection film coefficient is taken as 15 W/m^2 K. One thing I have also noticed that if I use the Gaussian heat flux ((3Q/Pi X r"^2) X exp(-3 X (r/r")^2)) instead of constant one, the top and bottom surface temperature comes as: 16000 degree C and 1500 degree C respectively. What may be the probable deficiency ? One last thing why 3 is multiplied with Q in case of Gaussian heat flux ?



Kindly help me in this regard. I got stuck into this for a long time. Any contribution will be highly appreciated.

Regards-

 Debabrata.