The authoritative public forum
  for Metal Finishing since 1989
-----

Heat treating air quench contamination - NH3 (ammonia)

2006

Hi,

What is actually happening to cause contamination of air quench NH3 during a heat treat process?

We are finding a silicon oxide deposit (lab verified) after heat treat on our 410 steel components. The deposit is green in color.

The explanation given by our supplier is gas contamination. We are unsure how such contamination would be introduced into the air quench.

Is it contamination of the NH3 gas in the cylinder? Is it contamination leaking into the oven from outside? How could silicon oxide be formed during this process?

Could this deposit accelerate corrosion or otherwise be detrimental in the field?

Thanks,

Kelly Kane
Automotive Supplier - Chicago, Illinois, USA