- Nov 23, 2018
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That's a great idea to use the lathe as a mill to cut the keyway.Ajoeiam, re post #245: Distortion after welding is usually a combination of the size/stiffness of the parent part, and the amount of weld and heat input.
Simply: The weld is molten, so when it "freezes" and becomes attached to the already "frozen" parent metal, it is cooling from a state that is hotter than the parent metal. The differential contraction as parent metal and weld metal cool cause internal stresses at the weld interface... and if great enough to distort the parent metal it is these stresses that cause distortion. Uneven cooling can make that condition worse, as we tend to cool parts with quenching "the far end" of the part, but this can cool the parent metal faster than the weld and exacerbate a problem that is inherent in the welding process. Pre-heating and normalising are simply ways to reduce weld stresses, thus reducing distortion. But microscopically, all weld repairs distort parent metal because we lay and bond molten metal onto cooler "frozen" metal. It is just that we can get away with some very small distortion when it is so small it is within tolerance.
I was thimpfking there might be several ways to reduce the heat distortion. One wojuld be to pein it, usually done on cast iron, however, it may actually work on steel but I don't know for sure. Another way would be to make very short welds, allow to partially cool before making another. and continue like that till the weld area is very shallow. It is already shallow, at the deep end it is only about 1/8th" deep but less than that wide. and it all narrows down in about an inchand a half. Truthfully, I am not familiar with these types of things. When I weld it is for structures.
I'm thimpfking that a combo of these things might be the way to go, and also that the weld area itself might be small enough to not be too serious. Any ideas?