welding a-36 to 4140
welding a-36 to 4140
(OP)
We have a bull gear 214 tooth (142.667" pd) made of 4140 steel through hardened to 245-285 BHN. We are trying to weld it to a36 5/8" thick steel mixer drum. Both items must remain "very round". any suggestions?





RE: welding a-36 to 4140
The 4140 will harden in the weld heat affected zone and will be brittle and prone to cracking unless you carry out a post weld stress relief heat treatment - this in itself is likley to cause some dimensional changes.
RE: welding a-36 to 4140
Because of the hardenability of 4140 alloy steel, you could also look at using a temper bead technique to avoid stress relieving. Before attempting this method, I would generate a weld coupon to optimize the welding parameters to verify softening of the heat affected zone.
Preheat of 350 deg F is recommended and staggering the weld passes should be done to balance shrinkage stresses. The concept would be to apply a "butter" layer on the 4140 side of the weld joint and lay subsequent weld passes while remaining on top of the butter layer to temper the 4140 alloy steel heat affected zone. The interpass temperature should not exceed 700 deg F to avoid generating too much heat to affect the gear heat treatment. If the temper bead technique can provide adequate softening, it may help to keep distortion to a minimum.
RE: welding a-36 to 4140
BK
RE: welding a-36 to 4140
RE: welding a-36 to 4140
RE: welding a-36 to 4140
RE: welding a-36 to 4140
Excellent suggestion. We will investigate. Thank You
RE: welding a-36 to 4140
BK