1566 Shaft to 1018 Plate

admin

Hi. I'm going to fix a .75"dia. 1566 shaft to a .25" 1018 plate perpendicularly. I have room to weld a shaft coupler to the plate but I can't get the coupler until tues and I want to finish today. I'm considering welding the shaft directly to the plate but I'm not familiar with the process and am concerned about the weld integrity. A quick Google search didn't give a cut and dry answer, but did add some questions. Most suggest preheating to 400-500 degrees and some  suggest tig welding with 309 or308 before mig. I'm hoping one of you is familiar with this alloy combo and can verify a process that I can trust. Thanks for your consideration.
Reply:Your 1566 shaft is a med-high carbon steel that is alloyed with Manganese for increased strength and toughness.  It is a very-easy-to-harden grade of material that will air quench to 60 Rockwell C(e.g. file hard).  Tensile strength annealled is about 70KSI and yeld is about 40 ksi.  This is roughly 2x the strength of your 1018 material.  Depending on what the end use is, you should be able to weld this with a standard 70KSI filler metal (E7018, ER70S-X, E71T1)  The pre-heat recommendation is OK.  YOu could weld this with stainless 309L filler, but there's no real advantage to doing so.The trick is that somewhere above the weld in the shaft the material will get hot enough to quench and harden when it cools.  So you'll have a band of steel just outside the HAZ that is hardened and untempered(very brittle).  The only way to fix this is the heat treat the whole piece in a furnace and anneal the shaft, or quench and then temper the whole shaft to an intermediate hardness.Your shaft will not likely be as straight as it was when you recieved it after all this heat treatment.In your shoes, I'd wait for the coupler...Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:Thank you for the thoughtful reply. The brittle spot you mentioned is exactly where I don't want one; the coupler is the way to go this time.