410S to 516-70 carbon steel

[Sleegers]

I’m looking for some advise on welding 516-70 carbon steel to 410S stainless. I made some new PQR’s using 5/16 and 3/16 plate with .035-309L – HiSil hardwire, with our Lincoln STT for a open root. Then proceeded to cap it with 309L flux core. The bend test failed on the face side (It split on the 410 side and followed the edge of the weld zone to the root). I have tried capping it with 309L rod but had the same if not worse results.

If you have any advise/knowledge on this material that could help it would be greatly appreciated.

 

[gtaw]

Welding dissimilar metals can always be a bit dicey.

The 410S is a modification of 410 martensitic stainless steel. The carbon content is reduced to reduce the tendency to harden when cooled in air.

The 516 grade 70 has a relatively high carbon content in comparison to the 410S.

Based on the thickness you are welding, I assume you are using single pass weld beads to span both the 516 and 410S. That means there is considerable dilution from the base metals. The 516 can contribute carbon to the point where the weld interface of the 410S has sufficient carbon to become hardened. Simply put, the chemistry of the 410S along the interface is more like 410 with sufficient carbon to be harden upon cooling.

You didn't mention preheat in your post. I would suggest that the filler metal selected, 309L, isn't a bad choice. The alternative is 430. I would try one more time with the 309L, but use high preheat to avoid high hardness at the weld interface of the 410S on you next attempt.

Check the diameter used in your guided bend testing apparatus. You may have to go to a larger bend radius to pass the test.

Best regards - Al

 

[Sleegers]

pre heat was 400F and interpass was kept below 500F. Air cooled after test.
The vessel get PWHT at 1150F (1hr min).
Single beads in 2G postion

 

[gtaw]

Eliminate the air cool. Go directly into PWHT cycle. Try annealing the weldment as if it were 410 martensitic stainless steel.

I suspect the introduction of carbon due to dilution with the 516 is the root cause of your problem.

Best regards - Al

 

[Sleegers]

First thank you for the quick resonds.

The 410S is no longer going through the pressure boundry (due to failing to pass impact testing) we have changed the design (repaced a rolled 410S plate that maked a 16" nozzle with a 16" SA 106-B pipe and weld overlay). There is a 410S 6" internal pipe(rolled plate with long seam, which is 410S to CS 6" pipe then going through the pressure boundry),header assembly and box with tray compartments that must be welded into place before hydro and PWHT.
I have been reserching this for some time now and have not herd anything about Inco 182?? Have you welded these dissimilar metals with this filler metal before??
We do not do the testing in house so it is getting very costly to keep testing with negative results

 

[gtaw]

I have no experience with the Inco.

Best regards - Al

 

[metengr]

Please do not cross post with forum794