Rewelding of 17 - 4 PH 1

[HardMetal]

I have a complex structure that was assembled by electron beam welding 17-4PH sheet (0.090 inch thick) in the corners. The sheet is now in the H925 condition. The welds were supposed to be full penetration welds, but turned out to lack full penetration. They are around 0.050 - 0.070 inch penetration. Due to the welded and assembled configuration, it is impossible to EB weld at this point unless special fixturing were made. This welded component is ugently needed to be assembled on another structure.

Does anyone have any idea or suggestion as to what could possibly be done to repair or improve the weld configuration without having to reheat treat the component? Is there a low temperature braze that could be used to fill in the unwelded fillet from the back-side of the weld? GTAW would produce a heat affected zone that would have to be reheat treated (or would it?).

Thanks for any help on this.

Paul

 

[Metalguy]

The easiest way out of this problem might be to perform an analysis to determine if you really need a lot of strength in the affected areas.

If you do need the strength, welding w/o full HT, including sol. ann. at high temp. won't work.

 

[HardMetal]

I realize that, of course. We do need full strength as the corner is a highly stressed area.

 

[Metalguy]

Then I don't see any alternative but to weld it with the right filler metal, and *completely* HT it again-sorry.

 

[NickE]

Seconds to Metalguy....

If you know that the part is mission critical and really needs the strength that you've obtained using 17-4 and H925 then there is really no way that I cna see around re-doing the whole bit.

nick


Nick
I love materials science!

 

[HardMetal]

Thanks. That was my opinion also but I was hoping someone had another idea or way around it. It's not a structure that can be reheat treated. It's a complex shape of sheet metal welded together. Re-heat treating would cause extensive distortion.

Paul

 

[CalvinKelly]

It is difficult to weld 17-4 in the H925 condition. At least heat treat it to the H 1150 condition, that is, take the current structure and heat 4 hours at 1150F. After weld repairing you will have to re-solution anneal 1900+-25F 1/2hour rapid cool. "Rapid cool" depends upon how large is the structure, a good nitrogen quench from vacuum might do. Unfortunately some distortion may occur.

 

[DJ1958]

When distortion is a concern during HT, fixturing the component works well for us.

 

[HardMetal]

We have GTA welded the structure in the H925 and then re-heat treated at 925F for 4 hours. Mechanical tests have proven acceptable: the structure was pressurized and did not fail at a pressure well above the required operating pressure (MEOP). There was no problem with distortion.

 

[Metalguy]

Good news! We seldom get follow-up info.

 

[NickE]

congrats....


Nick
I love materials science!