Survey Question: Does everyone use preheat welding 410SS?

Date 09-25-2009 20:01

The general guidance for (best practice) welding 410 SS is to use a 350-400F preheat to avoid cracking due to martensite formation and shrinkage stresses I presume.

We have welded many 410 details for decades with no preheat, and no cracking problems. I am talking about edge butt and square butt welds on tubing. I will say that we may get away with it because they are usually dissimilar welds to Inconel or other stainless alloys, and the welds are small and heat sinks low.

Now, we have a 10 or 20-year-old legacy part that is cracking. One side is 410, and I am still waiting to hear from the supplier what the current material is for the mating part. It may be 410 or a 300. (It is not stated on their drawing and this is a purchased part.)

What are the odds that something in the 410 chemistry has drifted to shift the weld metal to a higher percentage of martensite formation? I have not contacted the supplier to see if their material certs are even traceable, but I will try that route first I suppose.

By ssbn727 (*****)

Date 09-25-2009 22:11

Hi OBEWAN!

What is the thickness of the 410 stainless?
If it's less than 1/4" thick then I believe it is NOT required or necessary. Then again I may be thinking that this only pertains to 400 series ferritics so, just to make sure, look at the book below...

Take a look at this book and go underneath where the cover of this book Titled "The Alloy Digest Sourcebook: Stainless Steels" is shown to then click the link for you to preview the book via "Google Books." Then look at the table of contents and click the Martensitic grades of stainless steels once there you can read in the chapter regarding the precautions involved with weldability. Enjoy the read!!! ;)

Respectfully,
Henry

By OBEWAN

Date 09-25-2009 22:50

I found a source that says for 410 martensitics preheat is not usually required for less than 3mm thick. We are only about .035" so we should be fine. It did warn that shifts in chemistry can effect this, so I need to dig more into what we are actually welding in terms of chemistry. It may even be a hot crack, but I don't think 410 is known for that kind of problem. I may learn more if I do some metallography on the rejects too.

By RonG

Date 09-26-2009 02:48 Edited 09-26-2009 02:56

OBEWAN, To give an answer to your question: We weld from 405 t0 422 to mild steel, 410 and CoMo on a regular bases with out that much preheat using mostly INCO 82 and on rare occasion 309L.

We try to use preheat but all the welding is manual with extreamly difficult access and visability (you almost have stick youre head up against the work to see or reach where you need to weld. I know what goes on when no ones is looking for I have made the same welds for many years. Crater cracks have happened but from poor pratice by the individual.

We have never had a problem with cracking with fillers other than ER410. When we must use the 410 filler we watch the preheat much closer.

One advantage to 410 is its heat risisting propertys, the heat is not so quick to travel out and dissapate so a lot of times we just wrap some insulation around finished welds.

The welds are Fillet and material thickness is from .12" to 1.+" on the Air foil where as the ring maybe any where from 3/4" to 12" max cross section.

Don't really amagine thats much help to you but thats my story and I'm sticking to it.