Duplex to 4140 pipe

[twoheads]

is it possible to retain both mechanical properties? I would have a imagined problems with trying to keep the duplex cool yet maintaining a suitable preheat on the 4140.
Would the 4140 not have to be buttered first and subjected to post weld heat treatment prior to being joined to the Duplex.
What of a suitable filler , 309lmo? Zeron 100?

Any help on this one would be greatly appreciated,

thanks.

 

[metengr]

Use the 309MoL for joining the duplex ss to the 4140. I would butter the 4140 and if necessary, PWHT. Once this is completed, weld away with 309LMo to complete the joint with no PWHT and minimal preheat.

 

[MikeMet]

It all depends on what you are looking for and what you mean by "both mechanical properties". What metengr described will join the two parts together. The base metals will retain their original properties. However the weld will not a lower strength as either base metal and will be susceptable to chloride stress corrosion cracking. If you want the best of all worlds I would friction weld the two together if possible. You get a strong weld and no loss of base metal strength. If you need a strong weld between the two parts, you can butter weld as metengr described, but use Inconel 725 filler metal which has very high as-welded strength. Make sure the butter pass on the low alloy steel is at least 3/16" thick after machining the bevel to ensure you don't get a hard HAZ in the low alloy steel from the heat of butt welding.

 

[Guest102023]

metengr nailed it.