Tempering/stress relieving a welded spring shank

[Jim Rankin]

I have repaired several spring shanks from a fertilizer applicator toolbar by MIG welding. In the past these repaired shanks have always rebroken in fairly short order, and were only a temporary stopgap until new shanks could be ordered.

New shanks are no longer available from the manufacturer so I would like to do whatever is necessary to make these last as long as possible. They are about 1-1/4" square steel bent in a 2 coil spring with a straight section for mounting to the toolbar and a curved section that the injection knife mounts on.

These were repaired by V-ing out the break and using ESAB 1/16" FC wire shielded by CO2. Probably should have used something else, but that's what I had on hand.

How can/should I stress relieve/anneal/temper these.

[K D Redd]

I think you will have better luck using a welding rod for springs. What I use is MG Industries MG 600. You can use it rod to weld leaf springs and torsion bars. It is also advertised for removing broken bolts. I have used this to repair left springs and to remove two broken from a track coupling on a friends D-6C Cat. The rod is VERY pricey.

Kent

[KeithW]

The basic process to make springs is this. Heat to red hot then quench. This makes it very hard and brittle. Then heat till it turns blue and cool slowly. This removes enough of the hardness to make it springy. Not sure what your filler rod will do during this process. Since only a short section was heated by welding it might be alright as is. Historicaly this type of repair and tempering was done by a blacksmith. If you can find a good one they should be able to repair them and make more for you.

keithw

[rfo2]

Hi Jim
The spring shanks are made from two types of steel, the real good would be 4140 and 4340, a real high senitel steel. The most comon is 1050,1060,and 1090 steel. A good heat treater and blacksmith can spark test the steel to tell which one it is. Heavy sparks are hi carbon which is the last two numbers of the type ,ie 1090 is 90 points of carbon and 4140 is 40 points of carbon. The carbon is the componet that causes harding so the higher carbon the higher hardness. 4140 is oil hardening steel and is heated to 1550F and oil quenched. The max harden is RC55 and is tempered at a lower temp to RC 42 to RC47, the spring range. 1090 is water harding steel and is heated to 1550F and water quenched. The max harden is RC 62 and is heated at a lower temp for the same spring range.
I have repaired many of these for my brother on the dairy and there are two types of repair. If the shank is broke out of the coil I can use 7018 rod and then heat the welded area to 800-900F to stress releave, that is just bellow red heat. If the break is in the coil the repair is very different, that is the spring. To repair you must anneal the steel before you weld, 1250F and slow cool. Do the weld with the same base material filler rod and then anneal again. After this you reheat
as above. I have repaired a lot both ways with good results.
I do have some help for dairy as I'm a manintance engine for a heat treating company so the equipment I need is available, been doing this for 30+ years.
I hope this helps you. You helped me with the Onan Gen last year for the Dairy backup. Any questions e-mail and I will try to help.
rfo2

[Jim Rankin]

Thanks for all the information!

I am afraid I will not be able to do much other than stress relieve what I have already welded with the mild steel wire. I believe I may try that because unfortunately all 3 are basically broken in the coil. One was just in the first bend from the straight end.

The last one that was broken a little farther down the straight and welded with 7018 and then finished with the wire has done a hundred acres since the repair, but as you say maybe those are the easy ones.

These cut on the chop saw with HEAVY sparks so I guess they are high carbon.

Anyone know of a manufacturer of these things? I can't believe no one is making them any longer. These were manufactured for/by the JohnBlue Co. who no longer makes them and they say that the company that they turned the business over to, also has quit.

You never know about such things, just have to contact someone who knows where such a thing is still in common use.