Weld Cracks IN 738

By SAAI Date 08-06-2004 19:57

We have a jet turbine repair involving buildup (restoration) of worn surfaces on an IN 738 component, using L-605 weld wire / TIG process (are extending a flange 0.020" to 0.075". Flange thickness is 0.060-0.070"). Currently, no pre- or post-weld thermals are allowed (it is doubtful the part could be re-solutionized due to distortion concerns). A previous literature search led us to develop techniques to reduce the heat input to the base metal as much as possible (currently use a water-cooled Cu chill block, minimum amperage during welding). Would like to further reduce reworks/cracks in the HAZ. Does anyone have experience with this type of scenario, or have a feel for whether plasma arc welding would result in less cracking?

By Lawrence (*****)

Date 08-06-2004 22:13

Welcome to the forum. Sounds like you work with Ringo eh? Or at least have very similar situations

This is what I said to him;
http://aws.org/cgi-bin/mwf/topic_show.pl?id=5638

I don't see plasma being a big improvement in manual operations for several reasons, the main one being manual welders can reduce heat input only so much with any process (gtaw or plasma) but the difference between the two is minimal. This being said, welder awareness on the floor of just how serious heat input can be is vital. Have the guys on the floor been shown sectioned samples of the subsurface flaws found in the heat affected zone under the weld nugget? Have you traced your blade lot reject rates back to specific welders stamps? You may be surprised to find that part if the problem is a craftsmanship issue.

Plasma would be a benefit in an automated environment.