- Title: Member
- Status: Offline
- Registered: 04/24/2009
- Posts: 1
Topic: black marks after passivation
We have some instances where weld marks are reappearing after passivation. All of these are interior welds. The exterior is lightly buffed at the weld mark using a scotchbrite pad, and then steam cleaned with a degreaser. Afterwards the entire surface is blasted with virgin broken glass blast then blasted with #8 bead blast. Finaly, we passivate with a citric acid bath. It is while in the bath that some weld marks reappear. Does anyone know what may be causing this issue?
- Title: Member
- Status: Offline
- Registered: 11/13/2007
- From: Charlotte, NC
- Posts: 248
Re: black marks after passivation
What is the material that you are passivating? And how consistent is the discoloration problem? How consistent is the welding (hand welded or robot welded)?
In some alloys, reheating the parts (like during welding) can cause a change to the alloy structure (and temper), which then reacts differently when passivated.
-Dustin Gebhardt,
CEF
Plating Engineer
Danaher Tool Group
Gastonia, NC
- Title: Member
- Status: Offline
- Registered: 07/17/2006
- From: IL
- Posts: 4
Re: black marks after passivation
Kbc12, what grade(s) of stainless are you dealing with here?
Posts [ 3 ]
Guest posting is disabled. You must login or register to post a reply.
