What was the nature of the welding process? Preheat? Weld rod? If you calculate the CE for the 8630, you will find this material will require elevated preheat because of the carbon content, which directly impacts HAZ hardness (higher carbon, higher hardness).
Preheat was 550F to 690F. GTAW Rod ER80S-D2, SAW Wire Classification EA3K-A3-H8 Made by Union/Thyssen and Flux Designation UV420TTR Made by Thyssen. PWHT was was 1220F.
What are the HAZ hardness values? You may need to butter the 8630 side of the weld joint, conduct a separate heat treatment at 1300 deg F, cool and finish the weld using the stated weld filler metal to avoid altering the X80 material.
According to my ASM Handbook Desk Edition, for 8630 steel, to reach 22 HRc, the stated tempering temperature is 1200 deg F for 2 hours. I would increase this temperature to at least 1290, probably closer to 1300 to achieve maximum softening of the 8630 BM HAZ.
In my limited experience the principal encounter OI have had with 8630 was in a cast version as a steam shovel bucket tooth but I noticed that you also cross posted this question in the Boiler and PV forum. I found that curious.
Just out of cat killing curiosity, can you say what it is that you are trying to join? Or am I being too nosey?
nadfourchon;
Your original base material hardness exceeds your final PWHT hardness requirements for service. Either select a high PWHT temperature for this application or reconsider your application.
