Welding carburized 8620 bushing
Welding carburized 8620 bushing
(OP)
We have are welding an 8620 bushing (masked on all surfaces except bore during carburizing) into an A36 plate. The bushing is about 7.5" OD with a 1.25" wall and we are applying a fillet weld on the OD corner. That is, we are applying weld heat about 1" to 1.25" from the carburized surface. The problem is that we are cracking the parts. The bushing is being preheated to 400-500F before welding and the assembly is air-cooled. Any suggestions are greatly appreciated.





RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
RE: Welding carburized 8620 bushing
your problem but here goes.
If you used copper as stopoff it may be initiating the cracking in the bushing. In some alloys Cu will initiate cracking when
incorporated into the weld metal. This coupled with having an
extremely brittle base metal could b part of the cause.
Normally when we weld an alloy steel where there is quite a
different in the base metals we use a high preheat as
recommended in the post by meteng. We always use a
higher alloy electrode such as Allstate 275 (ESAB. This is similar to 312 SS. The last part of our procedure is we immediately cover the weldment with insulation to achieve a slow cool.
Have you looked a alternate designs like mild steel with a tension bushing or,bore welding, or shrinking in a hardened bushing?
You may also call someone like Weld Mold Company and get their recommendations for an electrode and procedure.
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RE: Welding carburized 8620 bushing
A good cooling set-up [insulation to slow cooling rate] is a metal pan of vermeculite deep enough to cover the part by at lease 2" or so, with a hardwood board at the bottom of the pan to keep the part off the bottom of the pan.
Also use a process that uses a flux as it will help with the problems caused by the oxide caoting. SMAW 'stick' or FCAW-G 'gas-shielded flux-core' come to mind.