Joining different grades of steel.

admin

I am being asked to quote a job that looks like a paddle wheel 26 inches in diameter and 30 inches long.  The paddles and support structure are made of HRS A36 but the shaft was called out as crome plated 2.0 dia  X 48" long.  So after some discusion I get to pick the shaft material as long as it's polished and ground and not 1018 (to weak).  Any suggestion on a material that is mid grade for strength that is easily welded to HRS A36?  I have stick, mig and tig welders.  It looks like the stick welder with the correct rod is the choice or maybe a redesign so the shaft does not need to be welded to the structure??  Any advice would be helpful. Thanks!
Reply:Unless it will be heat treated after welding, increase the shaft diameter and use 1018.  Another option would be to build the wheel with a 30 inch long 2 inch I.D. 1018 tube, then insert a 48 inch long axle . . . maybe 4140HT . . .  through the tube.  Connect them with a series of plug welds 6 inches or more from the sides of the paddle wheel.  This way the welds will only be transmitting torque and not be carrying any bending loads.-jimDynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:8620 is strong (~100KSI with no heat treatment) with very good weldability and machinability. It is my go-to alloy for shafts.JohnA few weldersA lot of hammersA whole lot of C-clamps