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Phosphating of tool steel

2004

We use a casting of CH13 (hot worked tool steel investment casting)for our component making. This casting undergoes heat treatment (spherodising, machining, gas carburising, hardening and tempering, Hardness = 60 HRC) followed by sand blasting for surface cleaning.

While performing manganese phosphating, we find white patches. We are looking for a uniform black colour. Can someone help to avoid white patches. Phosphating is followed by tectyl 272 oiling. Corrosion test (as per ASTM ASTM B117) on the component with white patches show a good corrosion resistance.

G R Patel
Manufacturer, Power Equipments - Vadodara, Gujarat, India

Q. Dear sir

We are also facing the white patches after manganese phosphating. Can any one suggest the same for better control?

Prakash G
- Bangalore
April 9, 2012

adv.

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