Heat tint is expected when heat treating a 410S? Presence of this so called "scales" shoul

[lmrodriguez]

The scale was eliminated months ago but one more time this scale has been found. The material is los alloy cladding 11/13 Cr and it has been treated in accordance with ASME VIII (750ºC, hold time 2 h).

This scale may affect to mechanical properties (Design Temperature 430ºC)

 

[lmrodriguez]

This is the question:Heat tint is expected when heat treating a 410S? Presence of this so called "scales" should not be regarded as a concern from a corrosion resistance point of view??"

 

[metengr]

Yes, surface oxidation of the 410 stainless will occur during heat treatment in atmosphere. If the 410 is being used for corrosion protection, surface oxidation/scale should be removed after heat treatment for optimum corrosion performance. Mechanical properties will be unaffected.

 

[lmrodriguez]

The surface was pickling and passivated months ago after heat treatment, but now we have the same problem. Do you know why ASTM indicated "Solutions of nitric acid alone are usually not effective for removing heavy oxide scale"? Perhaps it is necessary other type of test...

 

[metengr]

lmrodriguez;
You lost me. Did you recently have to re-heat treat this material because of weld repair? If so, the material will re-oxidize as a result of exposure to 750 dig C for 2 hours in air. Normally, I would prefer light grit blasting or rotary scotch brite pads after all loose scale has been removed from the surface.

 

[EdStainless]

The corrosion resistance is not really an issue. Your heat treatment probably sensitized the 410 so badly that it will suffer corrosion anyway. Unless this was very low C material.
The best way to remove heat treat scale and tint from objects like this is to blast and then passivate with nitric acid.
For smaller all stainless parts you could pickle in mixed acid, but you don't want to do that on clad material

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[Screwman1]

I agree with Ed that for corrosion resistance, 410 heat treated is not a good choice. Did the discoloration come back? My guess is that you had heavy scale that was not able to be clean off by the passivation dip. In that case you need to add some type of mechanical removal (bead blast, wheelabrate) and then repassivate.