Q: I need some advice as to the welding rods/electrode for Inco 840 burner ramps to Inco 840 pipe. Will Thermanit 21/33 work?

A: The Incoloy 840 is essentially a fully austenitic stainless material with a nominal composition of 21 percent nickel, 19 percent chromium, 0.03 percent carbon with a balance of iron.

For a high temperature application like your burners, you would be wise to use a ER310 stainless filler metal.

The ER310 filler has a nominal composition of 0.12 percent carbon, 26 percent chromium, and 22 percent nickel which in total, slightly exceeds the alloy of the Incoloy 840. That is good practice when dealing with this alloy system.

The elevated chromium in the ER310 filler should provide good oxidation resistance as well.

This filler alloy will be fully austenitic as is the Incoloy 840, and will be somewhat sensitive to centerline cracking during welding. The goal here is to weld “ugly” or, in other words, more convex to combat the cracking tendency.

Processes such as stick electrode (SMAW) or MIG (GMAW) are preferred over TIG (GTAW) to reduce heat input and to provide the necessary convexity to reduce the cracking tendency.

The Thermanit 21/33 filler metal you mention is supplied by Thermanit, a company based in Germany.

The nominal composition is essentially 0.20 percent carbon, 22 percent chromium, 33 percent nickel and 1.7 percent niobium, and is marketed towards high temperature applications, and it has good resistance in carburizing atmospheres. The composition appears to be appropriate for the application, and is available in both SMAW and GTAW products. Centerline cracking still may be an issue, therefore take precautions as listed above.

Q: I am rebuilding a J.I. Case 580 backhoe bucket.

The customer wants to use AR-400, abrasion resistant steel, for the bucket side plates and wear strips (heel bands) on the bottom.

What stick electrode do you recommend to weld T-1 (ASTM A514) steel to AR-400 plate? The plates will vary from ⅜ in. to ¾ in. thick.

A: A good quality E7018 or E7018-1 is a good choice for this application.

It is important that the low hydrogen electrode is properly stored to ensure that it retains its low hydrogen characteristics.

Using a lower strength filler metal generally is preferred as long as it meets the mechanical requirements of the weldment. Lower strength filler metals produce lower residual stresses and reduce the chances for hydrogen assisted cracks in both the A 514 and AR400 materials.

Welding joints typically used in the fabrication of buckets are lap and fillets that can be oversized to generate more weld strength if desired. Typically these types of materials are used as a wear surface and are not used as a structural component of the bucket. The weld is used to hold the AR-400 plate in place.

This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: askdav@penton.com.

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