Thin Wall Stainless tubing

Date 03-05-2001 19:46

If the spatter comes from a carbon steel weld, you're prone to experience intergranular corrosion in the places where the particles (droplets) had hit the stainless surface. Unfortunately, intergranular corrosion presence and its extension are only detectable with destructive methods. Also unfortunately, once the stainless steel has got contaminated with the carbon present in the carbon steel, there are no methods to remove it other than grind it off (with an alumina grinding wheel, not silicon carbide), which you don't want to do.
So, the best solution (and possibly the only one) is to be careful and make carbon steel welds well away stainless steel items.
Giovanni S. Crisi
Sao Paulo - Brazil

By petethomas Date 03-19-2001 17:01

(with an alumina grinding wheel, not silicon carbide), could you please explain
pete

By G.S.Crisi (****)

Date 03-23-2001 18:25

The most widely used grinding disks are made of silicon carbide (chemical formula SiC, hardness nº 9 in the Mohs scale, black color). A very well known brand name of silicon carbide is Carborundum, who were actually the first producers of that material.
Now, silicon carbide has a problem when used for stainless steel: the metal (alloy, rather) that has been in contact with the disk becomes contaminated with carbon, and thus prone to intergranular corrosion.
So, for ginding stainless steel, a more suitable material should be used, and this is commonly alumina (chemical name aluminum oxyde, formula Al2O3, hardeness nº 9 in Mohs scale, white color). Of course, the metal (alloy, rather) becomes contaminated with aluminum, but this is not harmful, or if it is, it is certainly much less than contamination with carbon.
Giovanni S. Crisi