There is some confusion in the brazing industry regarding the correct use of the terms “passivation” and “pickling” when it comes to preparing metal surfaces for brazing.

Passivation of stainless steel components that have been brazed with a copper-based or silver-based brazing filler metal (BFM) should never be done after brazing has occurred.

Let’s look more closely at the contamination issues presented by outgassing of aluminum brazing products.

It is interesting to see that some of these aluminum materials need to be brazed at temperatures that are only about 10-50°F (5-30°C) below the melting points of those base metals!

Aluminum brazing continues to grow. As it does, I receive questions from people asking me: "Can I use available furnace time in my high-temp aerospace vacuum furnace to do some aluminum brazing?"

It’s never too late to be reminded of an important subject.

Question:
We are brazing an M-50 tool steel with a copper paste in a vacuum furnace at about 2040+/-25˚F for 3-15 minutes.