Welding Stainless steel- Heat tint.

[Hercules28]

Dear all,

I am welding 304L Stainless on 304L with a 308 filler. (TIG)

I get various rainbow colors. I know that brown to white means low to high Temp exposure.
But what does the blue mean?? Does it have to do with the quality of the argon?

Thanks,

Herc

 

[metengr]

It means you have heat tint (surface oxidation) from exposure to oxygen. You should be using welding grade argon gas.

 

[EdStainless]

Either moisture, oxygen in weld gas, or poor gas coverage.
The welds will have poor corrosion resistance.

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Plymouth Tube

 

[berkshire]

It could also mean you are welding too slowly and are overheating the weld area.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[metengr]

There should be a maximum interpass temperature of 300 deg F to avoid excessive heat input.

 

[Guest102023]

All or any of the above.

 

[stanweld]

If blue heat tint (higher temp) is in the base metal outside the weld toe, too small a gas cup size could also be a factor.