The chemical composition of the AISI Type 8620 compares with AWS 5.5 E8010-P1 weld rod (which is used for pipelines). Another choice of weld rod would be AWS 5.5 E10018M for the AISI Type 8620 base metal.
However, you need to determine the heat treatment condition of the AISI Type 8620 base metal before final selection of a weld filler metal. The mechanical strength properties of the weld filler metal can be as equally important as the base metal mechanical properties in certain applications. I would suspect that the pinion shaft would be heat treated (quenched and tempered), which requires careful selection of a weld filler metal.
Second concern is the preheat and post weld heat treatment requirements that need to be specified to assure minimal problems during and after welding. This would apply to the E8010-P1 weld rod that contains vanadium.
You also describe the part as a pinion shaft. If this is a pinion gear of some description it is probably carburized on the gear teeth. As part of the heat treatment following the carburizing operation it will have been tempered at around 350F and any temperature exposure above this will reduce the mechanical properties. Exposure of any carburized surfaces to temperatures over 350F will reduce the hardness of these areas dramatically.
I would not recommend E8010-P1 for this weld due to the potential for hydrogen cracking. Use a low hydrogen electrode r that matches the engineering specified mechanical properties fot the 8620 material such as that proposed by metengr.
The pinion shaft was (quenched and tempered). What we want to do is to recovery 1mm thickness on shaft diameter by welding deposition followed by machining. As Metengr says if we preheat the shaft about 260ºC following by filling weld with E10018M it should work?
Do you really need to weld? Would it be possible to build up the shaft by an HVOF process (high velocity oxy fuel) sucjhas those offered by companies like Praxair. These coatings give bond strengths of over 10,000 psi and are frequently used for shaft journal area repairs. They do not change the properties of the base material.
Wouldn't a snap ring and groove accomplish
much of the same? Possibly in the other
part rather than on the shaft, assuming that
the shaft is the weakest member.
