15-5 Weld Repair

[HakiNoir]

I have a forging cylinder block from a nonstandard PH/ martensitic grade. PMI results show 15Cr-5Ni-1Mo-0.8Mn-0.2V with 35-39 HRC. I plan to do the spark test or take out a core sample to decipher whether this is a PH SS or fully martensite. The bores in the block are washed out due to sand erosion at ambient temperature and high pressure. Based on the block geometry, I would like to avoid PWHT and use a bore welder (i.e. boretech) to build up the bores and machine afterwards. ER630 would be good option but with no PWHT, I am not sure it will have enough hardness for wear resistance. Considering that bore welder likes to use solid wire 0.035" GMAW any suggestion on the welding wire to meet 35-40 HRC? I know that 625, 617 or 307 will get work harden during machining but not sure to what hardness level and what extent they are going to be wear resistant?

Your input would be much appreciated! Thanks.

 

[metengr]

First, this is not a 15-5 PH stainless steel. There is V present, and this forms carbides that promotes hardening. I would perform a complete chemical analysis versus relying on PMI to ensure proper selection of weld wire, not 17-4 PH wire.

 

[EdStainless]

You need to run OE or combustion and get a good C value, but this look to be martensitic.
You really have two options, and since you ruled out he best one that leaves you few choices.
The best option would be to over-temper this part, weld with a suitable high Cr martensitic filler (19-9 maybe), and the give the entire thing the correct HT.
I would look at using a Co based hardfacing alloy if you must avoid HT.

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P.E. Metallurgy, Plymouth Tube

 

[HakiNoir]

Thanks Metengr and EdStainless for your suggestions. I'll let you you once I get the chemical contents.

 

[metengr]

If you weld restore the bores, I would use an austenitic, Ni-base filler metal,and deposit Stellite 6 on top of that like a butter layer. Any hardfacing directly applied on this base metal has the potential to crack.