Weld strength of nitrided parts

[scides]

What is the magnitude of the effect on weld strength of welding a nitrided part? The formation of iron nitrides will have some effect but I have not been able to find values suitable for design calculations.

A little background into my application:

A nitrided 1010 pin is welded all around to an A36 plate with 29S wire. The loading condition results in a max stress of ~18000 psi on the weld.

Since the stress on the weld is low it would probably be strong enough even with the nitrided part but I don't want to make a design decision on a gut feeling.

If anyone could point me in the direction of reference material I would really appreciate it.

 

[TVP]

I highly doubt you are going to find design data for this. Welding into the nitrided layer is not recommended for a variety of reasons. You mention a max load, but does the load vary with time (cyclic)? Fatigue and fracture properties will be quite poor in a weld zone that has been previously nitrided.

 

[metengr]

I would agree with TVP on this because welding of nitrided surfaces requires extreme caution. I have seen nitrided tool steels weld repaired using austenitic based filler metls under carefully controlled preheat and interpass temperatures. I would not risk it for your application.

If you can, locally remove the nitrided surface layer and weld the pin to the A 36 base material.