Corrosion Resistant Overlays Harness

admin

Looking for some expert advice.I've been working on API 6A Corrosion Resistant Overlay PQR's API refers to NACE MRO175 for hardness requirements. I'm about 20 points too high on vickers 10 for the HAZ.I let this thing air cool once it was done being welded with no PWHT.Anyone have experience with this? I nee this thing to pass.
Reply:What process are you using, and what is the base material and the cladding material?  Do you have a technique sheet to follow?Based on the answers to these questions, there are several guidelines to suggest.Rich
Reply:Originally Posted by steelsurgeonWhat process are you using, and what is the base material and the cladding material?  Do you have a technique sheet to follow?Based on the answers to these questions, there are several guidelines to suggest.Rich
Reply:So, the base metal is 4130. What are you cladding it with? Stainless, or inconel?Usually a technique sheet is required to give guidelines on all the welding parameters, preheat and interpass temperatures, and general notes.If you don't have anything to follow, how are you approaching this test? Following a procedure will help reduce the HAZ that is haunting you.What does the test consist of, and how is it tested? I know how our cladding tests are tested...the weld surface gets LP tested, after it passes a visual test. Then strips get cut out of it and the depth of the strips get polished and macro-etched.There's lots more involved, but this is the gist of it.Rich
Reply:Thanks Rich-Welding with inconel FCAW and 4130 GMAW. I didnt gat a technique sheet from the wire MFG. We've been approaching it our previous experience of castings with similar material properties. Our PQR testing will get a LPT, Macro, Chemical and Hardness to Vicker's 10.I asked the lab to PWHT under the direction of my customer's welding engineer that deals with this type of stuff all the time. Hopefully that will fix the hardness issue.
Reply:I don't know a lot about PWHT of a bi-metal weldment. Hopefully the HT does. The different metals will react / heat up / cool down at different rates. We don't heat treat any of our tests.If successful, the PWHT should help with the hardness issue.Do you have to be concerned with dilution? This is usually something that corrosion resistance cladding tests get checked for for.Basic techniques for cladding include running stringer beads that overlap each other by 75%. Another recommendation is to run each bead in the opposite direction of the previous bead. Usually a minimum of 2 layers of weld are run, to allow for machine surfacing of the weld. Who dictates how you go about welding this test? Any "rules" to follow?I'm very curious about this.Rich
Reply:I'm no expert on this by any means but preheat and interpass temperature may play an important role.
Reply:Dave, you are absolutely correct!Rich
Reply:I welded some 4140 with 11018 and it called for I think 650 deg. preheat!